Integrated communication network for use in a field device management system

Abstract

A field device management system includes an interface which provides communication between a software application implemented on the system and a set of smart field devices coupled to the system. The interface accesses information from and/or writes information to the smart field devices, a database and device descriptions associated with the smart field devices to provide a consistent communication connection with such devices, database and device descriptions, irrespective of the types of smart field devices connected to the system. The interface is based on a predefined hierarchy of categories of information defining the device data associated with the smart field devices, and is implemented using an OLE object for each of the predefined categories of information. In particular, each OLE object stores device data associated with one of the predefined categories of information and includes instructions for communicating with one of the smart field devices, one of the device descriptions and/or the database to effect a command related to the stored device data.

Claims

We claim:

1. A field device management system adapted for communicating with a field device having device data associated therewith and with a device description storing a subset of the device data therein, the system comprising:

means for communicating with the field device;

means for interpreting the device description to obtain the subset of the device data stored therein; means for storing a hierarchy of categories of information associated with the device data, including means associated with each of the categories for defining communication procedures related to the device data associated with that category;

means for initiating a command related to a portion of the device data;

means for categorizing the command as related to one of the categories of the predetermined hierarchy of categories of information; and

means responsive to the categorizing means for controlling the communicating means and the interpreting means in accordance with the communication procedures associated with the one of the categories.

2. The field device management system of claim 1, further including a database for storing another portion of the device data, means for interfacing with the database and further means responsive to the categorizing means for controlling the interfacing means in accordance with the communication procedures associated with the one of the categories.

3. The field device management system of claim 2, wherein the another portion of the device data includes data related to a past configuration of the field device.

4. The field device management system of claim 2, wherein the initiating means initiates a command to retrieve device data from one of the field device, the device description and the database.

5. The field device management system of claim 2, wherein the initiating means initiates a command to store device data in one of the field device and the database.

6. The field device management system of claim 2, wherein the initiating means initiates a command to have the field device perform a predefined function.

7. The field device management system of claim 1, wherein the predetermined hierarchy of categories of information includes a category related to the physical connectivity of the field device and includes a category related to the configuration of the field device.

8. The field device management system of claim 1, wherein the field device includes a functional block defining one of an input, an output and a control function of the field device and wherein the predetermined hierarchy of categories of information includes a category defining the block of the field device.

9. The field device management system of claim 1, wherein the predetermined hierarchy of categories of information includes means for specifying the interrelationship between a multiplicity of the categories of information and wherein the controlling means includes means for sending messages between two of the multiplicity of the categories of information according to the specified interrelationship to control the communicating means and the interpreting means.

10. The field device management system of claim 1, wherein the storing means includes means for assigning a moniker to a selected one of the categories based on the position of the selected one of the categories within the hierarchy of categories of information.

11. The field device management system of claim 1, wherein the storing means includes a set of objects in an object-oriented programming paradigm.

12. The field device management system of claim 1, wherein the communicating means includes further means for communicating with the field device through a portable communication device.

13. A device management system adapted to be coupled to a plurality of field devices that perform process control activities in a process environment and that have field device information associated therewith, comprising:

a library that stores a device description associated with each of the plurality of field devices, wherein each of the device descriptions stores a portion of the field device information comprising a parameter associated with the field device and a property associated with the parameter;

means for identifying a hierarchy of categories of information using the parameters and the properties associated with the parameters;

means for communicating with the plurality of field devices based on the hierarchy of categories of information; and

means for retrieving field device information from the device descriptions based on the hierarchy of categories of information.

14. The device management system of claim 13, further including a database capable of storing another portion of the field device information and means for interfacing with the database based on the hierarchy of categories of information.

15. The device management system of claim 14, wherein the identifying means includes means associated with each of the categories of information for storing field device information associated with that category of information and means associated with each of the categories of information, for defining the operation of the communicating means or the retrieving means or the interfacing means with respect to the field device information associated with that category of information.

16. The device management system of claim 15, wherein the storing means and the defining means comprise a set of objects in an object-oriented programming paradigm.

17. The device management system of claim 13, wherein one of the device descriptions includes field device information related to the communication format of one of the plurality of field devices.

18. The device management system of claim 13, wherein one of the device descriptions includes field device information describing the type of device information stored in one of the plurality of field devices.

19. The device management system of claim 13, wherein one of the device descriptions includes field device information describing the methods available for implementation on one of the plurality of field devices.

20. A system for communicating with a plurality of field devices, each of which has device information associated therewith, comprising:

a library which stores a device description for each of the plurality of field devices, wherein each of the device descriptions includes a portion of the device information pertaining to one of the plurality of field devices;

means for communicating with the plurality of field devices and with the device descriptions stored in the library; and

means for categorizing the device information associated with each of the plurality of field devices into a multiplicity of predetermined categories, wherein each of the multiplicity of predetermined categories includes;

means for storing device information associated with the category, and

means for controlling the communicating means with respect to the device information associated with the category.

21. The system of claim 20, further including a database which stores another portion of the device information for one of the plurality of field devices and wherein the communicating means includes means for interfacing with the database.

22. The system of claim 20, wherein the multiplicity of predetermined categories comprises a hierarchy of categories and wherein the categorizing means includes means for defining the interrelationship between each of the categories of the hierarchy of categories of information.

23. The system of claim 22, wherein the hierarchy of categories of information includes a category related to the physical connectivity of each of the plurality of field devices and a category related to the configuration of each of the plurality of field devices.

24. The system of claim 22, wherein the categorizing means includes a category specifying the time to which the device information stored by the storing means of another category is related.

25. The system of claim 20, wherein the categorizing means comprises a set of objects in an object-oriented programming paradigm, wherein each of the set of objects includes an object property and an object method, and wherein the storing means comprises the object properties of the set of objects and the controlling means comprises the object methods of the set of objects.

26. The system of claim 20, wherein each of the device descriptions is written in accordance with a device protocol and wherein the device protocol associated with a first one of the device descriptions is different than the device protocol associated with a second one of the device descriptions.

27. The system of claim 20, wherein each of the plurality of field devices includes a functional block defining one of an input, an output and a control function of the field device and wherein the predetermined hierarchy of categories of device information includes categories defining the functional block of each of the plurality of field devices.

28. A method of communicating with a plurality of field devices having device information associated therewith, comprising the steps of:

storing a device description for each of the plurality of field devices in a memory, wherein each of the device descriptions stores a portion of the device information;

identifying a hierarchy of categories of information describing the device information associated with the plurality of field devices and the interrelation between each of the categories of information;

associating a method of communicating with one of the plurality of field devices or one of the device descriptions for each of a multiplicity of the identified categories of information; and

using the method of communicating associated with one of the multiplicity of the identified categories of information to communicate with one of the plurality of field devices or one of the device descriptions.

29. The method of claim 28, further including the step of storing another portion of the device information in a database, associating a method of communicating with the database with a further one of the identified categories of information and using the method of communicating associated with the further one of the identified categories of information to communicate with the database.

Description

TECHNICAL FIELD

The present invention relates generally to management systems having applications that manage "smart" field devices within a process or a plant and, more particularly, to a communication network capable of communicating with one or more smart field devices within a process.

BACKGROUND ART

Typically, process plants (such as chemical refinery plants and drug manufacturing plants, for example) include many field devices which control and measure parameters within the process. Each field device may be a control device (such as a flow valve controller), a measurement device (such as a temperature gauge, pressure gauge, flow meter, etc.) and/or any other device that affects or determines a value associated with a process. Until the past decade or so, field devices have typically been rather simple devices which are controlled either manually or electronically and which produce output readings either electronically or on a gauge connected to the device. However, these devices typically only provide limited information to a controller such as analog signals pertaining to the readings or measurements made by these devices.

More recently, so called "smart" field devices have been developed. Smart field devices are capable of communicating with a process controller and/or a management system associated with the device. Typical smart field devices are capable of transmitting an analog signal indicative of the value associated with the device, for example, a measurement value, and of storing and also digitally transmitting detailed device-specific information, including calibration, configuration, diagnostic, maintenance and/or process information. Some smart devices may, for example, store and transmit the units in which the device is measuring, the maximum ranges of the device, whether the device is operating correctly, troubleshooting information about the device, how and when to calibrate the device, etc. Furthermore, a smart field device may be able to perform operations on itself, such as self-tests and self-calibration routines. Exemplary smart devices include devices which follow the HART (Highway Addressable Remote Transducer) protocol (HART devices), the Fieldbus protocol (Fieldbus devices), the Modbus protocol, and the DE protocol. However, other smart device protocols may exist or be developed in the future to support different types of smart devices.

Currently, every conventional and smart device is capable of performing one or more specific input and/or output functions with respect to a process. An input function is any function which measures or reads a value associated with a process, such as the function performed by a temperature or pressure measurement device. An output function is any function that changes something within a process, such as the functions performed by a valve or a flow controller. Furthermore, some smart devices, such as Fieldbus devices, can perform control functions which are functions associated with the control of a process. Each input, output and control sub-function performed by a device is referred to as a "block." By definition, therefore, each device includes at least one and maybe more blocks. Fieldbus devices usually include multiple blocks (e.g., one or more input, output, and control blocks), and, while HART devices do not include blocks per se, the contents of a HART device may be conceptualized as constituting one and only one block.

Each block and, therefore, each device includes one or more "parameters." A parameter is an attribute of a block which characterizes, affects or is somehow otherwise related to the block. Parameters may include, for example, the type of the block, the maximum operating or measurement range of a block, the mode of a block, the value of a block measurement, etc.

Likewise, each parameter has one or more properties associated therewith, and each of those properties defines or describes the information within the parameter. For example, the temperature parameter of a temperature measuring device has a label property which stores the name of the parameter (e.g., "temperature"), a value property which stores the value of the parameter (e.g., the actual measured temperature), and a units property which stores the units in which the temperature value is expressed (e.g., degrees centigrade or degrees fahrenheit). A device or a block configuration comprises a set of values for each of the properties of each of the parameters associated with a device or a block.

As noted above, smart field devices are developed so that communication therewith must be performed in one of several available protocols (the HART and Fieldbus protocols, for example). These protocols allow device manufacturers to provide device-specific types of information for a device and, of course, the particular types of information are different for each type of smart field device. Consequently, these protocols are complex and difficult to use in device programming. More particularly, some of these protocols do not provide a completely consistent method for communicating with every smart device conforming thereto. Instead, these protocols, such as the HART protocol, merely provide a way for device manufactures to specify what information is available from each smart field device and how to retrieve that information.

Communication with smart devices has been simplified to some extent with the advent of device description languages (DDL) and device description services (DDS) which are provided by the manufacturers of smart field devices. A DDL is a human-readable language that provides a protocol for describing the data available from a smart device, the meaning of the data associated with the smart device and retrieved therefrom, the methods available for implementation of the smart device, the format for communicating with the smart device to obtain data, user interface information about the device (such as edit displays and menus), and data necessary for handling or interpreting other information pertaining to a smart device.

DDL source files comprise human-readable text written by device developers. These files specify all the information available about a device between the device and a bus or a host to which the device is connected. Basically, in developing a DDL source file for a device, a developer uses the DDL language to describe core or essential parameter characteristics of the device as well as to provide group-specific, and vendor-specific definitions relating to each block, parameter, and special feature of a smart device.

A DDL source file is compiled into a binary format to produce a machine-readable file known as a device description (DD) which can be provided to a user by the device manufacturer or a third-party developer to be stored in a host system, such as a management system. In some cases, for example in Fieldbus devices, DDL source files may be stored in a smart device and transferred from the smart device to a host system. When the host system receives a DD object file for a smart device, it can decode and interpret the DD to derive a complete description of the interface with the device.

DDS is a general software system developed and provided by Fisher-Rosemount Systems, Inc. and/or Rosemount, Inc. for automatically decoding and interpreting the DD's of smart devices. More particularly, DDS is a library of routines which, when called by a host, interprets the DD of a smart device to provide the host with information pertaining to the smart device, including information pertaining to: (1) the setup and configuration of the smart device; (2) communication with the smart device; (3) user interfaces; and (4) methods available for use in conjunction with the smart device. One extremely useful application of DDS is in providing a consistent interface between a host system and one or more smart devices having associated DDL source files (and corresponding DD object files).

Although DDS, DDL and DD's are generally known in the art, more information pertaining to the specific function and format of DDL's, and of Fieldbus DDL in particular, can be found in the InterOperable Systems Project Foundation's manual entitled "InterOperable Systems Project Fieldbus Specification Device Description Language" (1993), which is hereby incorporated by reference herein. A similar document pertaining to the HART DDL is provided by the HART foundation.

A management system is a system which interacts with one or more smart field devices to read any of the device, block, parameter, variable, or configuration information associated with those devices. Typically, a management system comprises a personal computer having appropriate communication ports which allow it to interconnect to, communicate with, and reconfigure a smart device. Management systems may be on-line, that is, have a hard-wired or any other permanent connection with a smart device. Management systems may also be portable and capable of being periodically connected to a smart device to reconfigure that smart device.

Management systems typically perform a wide variety of functions with respect to smart devices within a system. For example, management systems may be used to provide users with information (e.g., values of variables or parameters) pertaining to the state of a process and to each of the smart field devices associated with or connected to the process. Management systems may also be used to enable a user to monitor a process and control the process by reconfiguring smart devices within the process as necessary.

The software routines which are used to perform functions within a management system using features provided by the system are generally referred to as applications. Typically, management systems implement applications provided by individual smart device manufacturers to implement changes on, and read data from, a particular smart device. As a result, various applications within a management system often do not share a common or consistent interface, and the transition from one application to another is therefore cumbersome and time-consuming. Further, smart device configuration data, configuration logs, and smart device diagnostic data created and stored by different applications are decentralized and cannot be cross-referenced because this data may be stored in diverse formats, in different databases and, in some cases, in proprietary formats. Consequently, tasks that could be common to each device within a system must be duplicated in separate applications.

A management system which implements such separately developed applications typically has no way to view information pertaining to all the smart devices in a plant or a process simultaneously because the applications for each device must be run separately. Furthermore, it is difficult for users to write applications that provide a comprehensive view of data pertaining to multiple, different devices in a process because users typically do not have a great familiarity with DDS or with the DDL and DD's associated with each of the devices within a process. Even if a user does have such familiarity, such applications are time-consuming and expensive to develop and must be updated each time a new smart device is added to the system.

The need for an integrated management system is particularly great in processes or systems which must be certified by government agencies such as the EPA and the FDA which regulate, for example, certain chemical and pharmaceutical processes to ensure that the products manufactured by those processes meet stringent standards, that emissions remain below a predetermined level and that safety procedures are followed. The easiest way for a plant implementing a regulated process to maintain its certification is to maintain records sufficiently thorough to prove to government auditors that the values of critical process parameters have remained at specified levels or within specified ranges that comply with the regulatory requirements of interested governmental agencies and safety procedures. An integrated management system coupled to the smart devices of a process can be used to automatically record these values in a database. Thereafter, the data stored in the database of the integrated management system can be used to prove that these critical values remained within respective required ranges.

Integrated management systems also can be used to reconfigure smart devices more regularly to maintain the certifiability of the process in which the devices are used. Currently, most management systems which support more than one smart field device include particularized software written for each supported smart device to allow communication with that smart device. Adding a new smart device to a process therefore requires the management system for that process to be reprogrammed. Once again, this programming is time-consuming and can be expensive because it must be performed by a person knowledgeable not only in the management system software, but also in the smart device protocol and the new smart device.

Although hand held communicators exist which interface with different smart devices following a particular protocol, these devices only read and write data from and to the device and are not capable of processing that data in any significant manner.

Still further, applications typically allow a user to view a current configuration of a device, block, or parameter within a process, but those applications do not allow the user to view past configurations or to display multiple configurations simultaneously to compare such configurations.

SUMMARY OF THE INVENTION

This invention is related to a management system which provides a consistent and generalized communication connection between an application and multiple devices connected to the system so that no new programming is necessary to communicate with, and display information pertaining to, a newly added smart device. In particular, a hierarchy is created to identify and categorize all of the types of information and data represented by one or more DDL's associated with one or more smart devices connected within a system and the interrelationships between those categories of information and data. An interface based on this hierarchy is then used to call, access information from, and communicate with a DDS associated with the one or more categorized DD's, smart devices connected within a system, and/or database associated with the system, to provide a consistent interface with such DDS, devices, and database, irrespective of the type of device connected to the system. Because of the consistent use of DDL's to access information pertaining to multiple devices, an application need not be reprogrammed to communicate with, read data from, reconfigure, or display data pertaining to a new device added to the system.

Preferably, this hierarchy includes a set of objects of different types which are defined within an object-oriented protocol, such as the now well-known Object Linking and Embedding (OLE) protocol. Each object includes properties and methods for operating on the data and is able to send messages to other objects within the hierarchy and to devices and hosts using the hierarchy to implement particular functions related to retrieving information from a smart device, database, or DD associated with the object. Preferably, the data within these objects represents subsets of the data available from and used by DDL's along with other information not provided by the DDL but useful to a host system or an application such as particular values, times that changes were made, identification of the users who implemented changes and the reasons for changes, etc.

A management system interface or communication network based on this hierarchy enables the management system to include all the functionality enabled by any smart device which has a DD. Thus, for example, a management system using this communication network allows the user the freedom to view multiple devices in a simultaneous or sequential manner, to perform common control and configuration functions without switching applications or interfaces, to run non-device-specific applications (such as browsers, which locate devices on the network, alarm lists, setup applications, and device status monitoring applications), and to run device-specific applications (such as device configuration, device calibration, and status-checking applications).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the interconnections between a process, a digital control system and a management system;

FIG. 2 is a block diagram of the management control system of FIG. 1 having a device communication interface which operates according to the present invention;

FIG. 3 is an upper hierarchy of object information according to the present invention; and

FIGS. 4A-4C are a lower hierarchy of object information according to the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a management system 10, referred to hereinafter as a Field Management Solutions system (an FMS system), interconnected with a process 12, a distributed control system 14 (DCS) which controls the process 12, and a further management system such as another FMS system 15. The process 12 may comprise any desired type of process, such as a manufacturing process or a refinery process, etc., and is illustrated as including four smart field devices, including three HART devices 16, 18 and 20 and one Fieldbus device 22, and a conventional (i.e., non-smart) device 24. The devices 16, 18, 20, 22 and 24 are controlled in any desired manner by the DCS 14.

Generally, the FMS system 10 is a PC-based software tool that includes applications which perform field-device management tasks. The FMS system 10 integrates device management for each of the devices within the process 12 by helping users to, for example, configure, calibrate, monitor and troubleshoot any and all of the smart field devices associated with the process 12.

The FMS system 10, which may comprise any type of computer- or microprocessor-based system, may include a display 30, a printer 31., a keyboard 32 and a mouse 34 connected to an operating system and CPU 36. A memory 38 having an FMS database 40 is coupled to the operating system and CPU 36. The memory 38, including the FMS database 40, stores software and data used by the FMS system 10 in performing tasks related to displaying information to a user via the display 30 or the printer 31 and communicating with the smart devices 16, 18, 20 and 22. In addition, the FMS database 40 stores device-related information which is not available from the smart devices, for example, information pertaining to past configurations of the devices, information pertaining to off-line devices, such as off-line smart devices and conventional devices, and information pertaining to service notes including when the next service is needed; who performed service procedures; any favored replacement devices, etc. Data pertaining to off-line smart devices may be stored within the database 40 in a format identical to the format in which that data is actually stored within the off-line devices so that, to the FMS system 10, off-line devices appear to be available through the database 40 in the same way they would be available if those devices were on-line.

The smart devices 16 and 18 are on-line devices which are connected to the FMS system via a communication line 42 and a modem 44. The smart device 22 is an on-line device which is connected to the FMS system via a Fieldbus interface 45. The smart device 20 is an off-line device which is not permanently connected to the FMS system 10. However, the smart device 20 may communicate with the FMS system 10 via a hand-held communicator and/or secondary (laptop) FMS 46 which may be periodically connected to the device 20 and/or any of the other smart devices to read data from, and write data to, the device 20 and/or the other smart devices. Thereafter, the hand-held communicator and/or secondary FMS 46 may be connected to the FMS system 10 to upload data pertaining to the smart device 20 and/or any other smart devices to which it was attached and store such data in the FMS database 40.

If desired, the operating system and CPU 36 of the FMS system can be connected through, for example, an ethernet communication link 48 and/or other network link to the DCS 14 and other FMS systems, for example, the other FMS system 15.

FIG. 2 illustrates the interconnections between various component parts of the FMS system 10, including hardware and software components, and will be used to describe how the various software components stored in the memory 38 of the FMS system 10 interact with each other, with the display 30, the printer 31, the keyboard 32, the mouse 34, the FMS database 40 and the smart devices within the process 12. It is understood that the software components of the FMS system 10 are stored in the memory 38 and are run on the operating system and CPU 36.

The FMS system 10 preferably operates in a Microsoft Windows environment (such as a Windows 95.TM. environment) and, therefore, includes a standard Windows operating system 49, which is used to display data and information on the display 30 and the printer 31 and to retrieve data and information from the keyboard 32 and the mouse 34. Thus, information provided to, or retrieved from, the Windows operating system 49 is preferably provided in a standard Windows call format of any desired type, as is known to those skilled in the art. However, the FMS system 10 could be implemented according to the present invention using any other desired Windows-based or non-Windows-based interface format (whether or not a graphical user interface) including, for example, MacIntosh, Xwindows or IBM DOS formats.

The FMS system 10 includes a set of FMS applications 50 comprising core applications 52 and add-on applications 54. The core applications 52 are essentially programs written by the FMS system provider to perform predetermined and frequently used operations. The add-on applications are applications which are developed by a user or a third-party developer and imported to the FMS system 10 to perform customized functions.

As used hereinafter, an application refers to any software routine implemented by the FMS system 10 which displays to a user information pertaining to or about the process 12 or one or more devices, blocks, parameters, or other information associated with the devices connected to, or associated with, the FMS system 10, and/or which allows a user to reconfigure one or more of the devices associated with or connected to the FMS system 10. The information used by an application typically is either stored in, or developed by, the smart devices within the process 12, or is stored in the FMS database 40.

Thus, for example, the FMS system 10 may include core or other applications which allow a user to interact with the data within the FMS database 40 and/or the smart devices within the process 12 to view the present state of one or more of the devices within the process 12, to change the configuration of one or more of the smart devices within the process 12, to view multiple devices in a simultaneous or sequential manner, to perform common smart device control and configuration functions, to run browsers that locate devices on the network, to monitor the status of devices and generate alarm lists, and to implement device calibration and testing routines.

Other typical core applications may include configuration applications, configuration-management applications, alarm scanning applications, history event-log applications, reporting applications, trend-analysis applications and diagnostic applications. A configuration application displays the values of the variables associated with one or more parameters of a device within a process and allows a user to change appropriate ones of those parameter values. A configuration management application allows a user to manage the configuration of the device as a whole, for example, resetting a device, initializing a device, and calibrating a device. An alarm scanning application checks all of the devices being serviced by the FMS system 10 to determine if those devices are operating correctly or if an error has occurred within any of the devices. A history event-log application provides an event log having, for example, user log-in information, time-stamped messages which indicate changes that have been made to the configurations of the devices being serviced by the FMS system 10, alarms associated with the devices being serviced the FMS system 10 and other events. A reporting application automatically generates a report showing, for example, all past, present or desired future configurations of one or more devices. A trend-analysis or "trending" application records data measured by devices within the process 12 to identify trends which may be occurring within particular devices or across a process as a whole. As is evident, any other desired applications can be created and provided to the FMS system 10.

During operation of the FMS system 10, a user selects one or more of the applications for execution. The selected application is identified in FIG. 2 as the current application 56. Because multiple applications may be executed simultaneously by the FMS system 10, there may be multiple current applications 56. Any current application 56 may interface directly with the Windows operating system 49, an interface block 58, a digital control interface (DCI) 60 and an FMS database interface 62. If desired, the current application 56 can also interface with an Open DataBase Connectivity (ODBC) block 64 (a well-known Microsoft database application interface (API) system that enables communication with nearly all databases) and a server network 65. For many applications, however, such connections are not necessary or desirable. Furthermore, any current application 56 may indirectly interface with the Windows operating system 49, the smart devices within the process 12, and the database 40 via the interface block 58.

The interface block 58 is essentially a software package having for example, specifically configured Windows custom controls, OCX controls or VBX controls, which automatically perform functions relating to the communication of particular, frequently used information between a current application 56, the smart devices within the process 12, the database 40, and a user interface 65 comprising the Windows operating system 49, the display 30, the printer 31, the keyboard 32, and the mouse 34. The interface block 58 can be used by a current application 56 to perform these interfacing functions without the application designer knowing the specifics of the protocols involved therewith. As a result, the interface block 58 enables an application to be designed more easily and provides a consistent user interface.

Preferably, current applications 56 and the interface block 58 interface and communicate with the smart devices within the process 12, other FMS systems or digital control systems and/or the database 40 through the DCI 60 and a server network 66 comprising servers 68 and 70. While typically the server network 66 will be located in, and associated with, the FMS system 10, the dotted line between the DCI 60 and the servers 68 and 70 in FIG. 2 indicates that the DCI 60 can also access server networks of other FMS systems through, for example, the ethernet connection illustrated in FIG. 1.

Essentially, the DCI 60 is a convenience layer which comprises a library of routines which perform functions necessary for communicating with, and retrieving data from, and other functions pertaining to the database 40, the smart devices associated with the process 12 and/or other FMS systems. In operation, the DCI 60 converts commands and messages sent from the current application 56 and the interface block 58 into a format recognized and used by server network 66 and, likewise, converts data provided by the server network 66 into a form recognized and used by the current application 56 and the interface block 58.

While the DCI 60 can use any desired protocol to perform these communication functions, the DCI 60 preferably uses an object-oriented protocol and, most preferably, uses an object linking and embedding protocol such as the Object Linking and Embedding (OLE) protocol developed and documented by MicroSoft, Inc. The MicroSoft OLE (2.0) protocol is used in the MicroSoft Windows 95.TM. operating system and is well-known in the art.

Generally, an object-oriented protocol is a programming paradigm which models the world as a collection of self-contained objects that interact by sending messages. Objects include data (a state) and methods (algorithms) that can be performed on the data. In addition, objects are related to one another through an interface connection and may communicate with other objects in the hierarchy through messages. When an object receives a message, it responds by using its own methods which are responsible for processing the data in that object and sending messages to other objects to perform specific tasks and possibly return appropriate results.

Because the DCI 60 communicates with the server network 66 through an OLE hierarchy, the DCI uses standard OLE procedures or calls relating to reading and writing values of OLE objects, enumerating a set of enumerated values in an OLE object, getting and setting properties in OLE objects, calling and implementing methods of OLE objects and retrieving property data stored in the OLE collection objects in conjunction with OLE Item methods (a particular type of OLE method). However, other OLE procedures can be implemented by the DCI 60 on OLE objects to communicate with the server network 66.

As described in more detail below, the particular OLE hierarchy which is preferably used by the FMS system 10 is an OLE object hierarchy which has been developed to categorize all of the different types of information and the interrelationships between the different types of information available for, or used by, each of the different DDL's associated with each of the DD's which, in turn, are associated with the devices within the process 12 being serviced by the FMS system 10. This determined hierarchy defines a set of OLE objects, each of which stores a particular set of properties as defined by the hierarchy and a particular set of methods which can be used to manipulate the property data and to communicate with other OLE objects according to the relationships defined by the hierarchy. This hierarchy will be discussed in more detail in conjunction with FIGS. 3 and 4.

Essentially, the DCI 60 communicates with the server network 66 as if all the OLE objects identified for the determined hierarchy exist within the memory of the server network 66. The DCI 60 implements a simple set of calls necessary for communicating with the OLE objects in the OLE protocol. In reality, however, the data and methods of each OLE object are not actually stored or placed in the memory of the server network 66 until a call, such as a read or write call, is sent to the server network 66 for such OLE object by, for example, the DCI 60, the DDS 72, the smart device communication network 74, or the FMS database interface 80. At that time, the server network 66 recognizes that the data and methods pertaining to the OLE object must be retrieved and stored in memory associated with one of the servers 68 or 70 and automatically performs the functions necessary to retrieve the data and methods of that OLE object.

When the server network 66 receives a call relating to the reading or writing of data or methods within one of the OLE objects stored in its memory, the server network 66 returns the requested information or performs the requested function to the OLE object data according to its stored routines so as to read data from, and write data to, the OLE object, the DDS 72, the smart devices within the process 12 and the FMS database 40.

Likewise, the DCI 60 recognizes or receives changes in OLE objects stored within the memory associated with the server network 66 and performs functions based thereon to implement communication with the current application 56 and the interface block 58. The device server 68 is essentially a set of software routines which have a specified correspondence with the set of OLE objects in the determined OLE hierarchy. These routines are specifically developed to communicate with a DDS 72, a smart device communication interface 74, and the OLE objects of the defined hierarchy. Such routines may, for example, transmit, retrieve, and change particular types of data and information stored within, or available from, the smart devices within the process 12 and/or from DD's (which are files) associated with the smart devices within the process 12. Likewise, the database server 70 is essentially a set of software routines associated with the OLE objects in the determined OLE hierarchy. These routines communicate with the DDS or API 72 and/or an FMS database interface 80 to, for example, transmit, retrieve, or change particular types of data and information stored within, or available from, the FMS database 40 and/or from the DD's which are associated with the smart devices for which data is stored in the FMS database 40. As indicated in FIG. 2, the DD's used by the DDS 72 are stored in a device description library 76 coupled to the DDS library 72.

The routines of the servers 68 and 70 are associated with each of the OLE objects in such a way that the routines which perform the particular read functions required for retrieving the data of an OLE object from the DDS 72, from smart devices, or from the database 40 are automatically implemented by a request for such data from the DCI 60. Likewise, the routines of the servers 68 and 70 are associated with each of the OLE objects in such a way that the routines which perform the particular writing functions required for changing the configuration of smart devices or storing information in the database 40 are automatically implemented by a request made by the DCI 60 to write such data in the OLE object.

For example, a request made by the DCI 60 to write the value property within an OLE object representing data within or associated with a smart device, will cause the server 68 to implement the routine which writes new property values to the smart device. Likewise, a request to read from any OLE object property values stored in, or associated with, a smart device will automatically call the server routine which retrieves the property values associated with that OLE object from the DDS and/or the smart device and store such property values in the memory (not shown) associated with the server 68 as the OLE object. Similarly, a request made by, for example, the DCI 60, to write the property values within an OLE object associated with data stored in the database 40 will automatically implement the server 70 routine which writes new property values to the locations within the database 40 with which that OLE object is associated. Likewise, a request to read property values from an OLE object will cause the server 70 to retrieve the data associated with that OLE object from the DDS and/or the location in the database 40 associated with those property values and store such property values in the memory (not shown) of the server 70 as the OLE object.

These server routines are simple, straightforward, and easy to write by those skilled in the art and are not, therefore, provided herein. However, those familiar with OLE and DDL's can create such routines in a straightforward manner using any desired programming language. If desired, the routines may be written or optimized in any desired way to perform in as high-speed a manner as possible to thereby increase the operating speed of the current application within the FMS system 10.

Generally, to retrieve specific data from, or pertaining to, one of the on-line devices of the process 12, the server 68 asks the DDS 72 for the specific data. If that data is stored in the DD for a smart device, the DDS 72 then consults the DD for the referenced device or the DD associated with a block of the referenced device and returns the requested data to the server 68.

If the specific data was available from the DD, the server 68 stores and maintains that data in the OLE object to which the retrieved data is related. If however, the requested specific data is not available from the DD for a device or a block of a device but is stored, instead, in the on-line device, the server 68 sends a command to the smart device communication interface 74 (which may comprise any known smart device communication interface including, for example, a Fieldbus device interface developed by SoftIng, a German company located in Karlsruhe, or the HART device interface of Micromotion, located in Boulder, Colo.) to retrieve the specific data from the on-line device.

The smart device communication interface 74 then sends a request to the DDS 72 for information on how to retrieve the specific data requested by the server 68 from the on-line device. The DDS 72 retrieves this instruction information from the DD for the on-line device and returns the instruction information to the smart device communication interface 74 which, in turn, sends a proper request to the on-line smart device. The smart device then responds with a data stream including the specific data. The smart device communication interface 74 then sends a request to the DDS 72 for information on how to interpret the data stream received from the on-line smart device. The DDS 72 then retrieves interpretation instructions from the DD for the on-line smart device and returns them to the smart device communication interface 74 which, in turn, interprets the data stream from the on-line device in accordance with the interpretation instructions in order to extract the specific data requested by the server 68. The smart device communication interface then returns the specific data to the server 68 which provides the retrieved data to the OLE object with which that data is associated.

The process of writing data to an on-line device is similar to the process of reading data from that device except that the server 68 first sends a request to the DDS 72 for write information, e.g., whether the data is writable, what type, specific values and range of data can be written, etc. If the data is writable, the server 68 sends a write command to the smart device communication interface 74 which, in turn, interfaces with the DDS 72 for write protocols for the on-line device and sends the proper write command to the on-line device in response to the information. The smart device communication interface 74 can also interpret other data from the on-line devices, such as write verifications, response codes, data or value changes which occur in the device, etc. and sends such data to the server 68 for storage in the proper OLE object.

In some instances, the DDS 72 will inform the server 68 that it needs more information to answer a request for data. For example, the DDS 72 may determine that the handling property of a parameter (i.e., whether the parameter is readable and/or writable) is dependent on the mode parameter of a particular device. The DDS 72 sends a request to the server 68 for the mode parameter of the device. In response thereto, the server 68 sends a request for the mode parameter of a device to the smart device communication interface 74 which operates as described above to retrieve the mode parameter of the device. When the server 68 receives the mode parameter of the device from the smart device communication interface 74, it sends this information to the DDS 72 which, thereafter, determines the handling property of a parameter of a device and returns such property to the server 68 which, in turn, places that value in the proper OLE parameter object.

Communication between the server 70, the DDS 72 and the FMS database interface 80 is similar to that described above, except that the FMS database interface 80 is programmed to read and write information to and from the FMS database 40 instead of a smart device. Generally, however, the FMS database interface 80 mimics the functions of the smart device communication interface 74 as they relate to communications between the DDS 72 and the server 70.

It is possible to have the FMS database interface 80 store information pertaining to, for example, values associated with off-line devices and data pertaining to changes made to on-line and off-line devices in the database 40 in a DDL format, i.e., in a format that mimics how such data is stored in on-line devices. In such a situation, the FMS database interface 80 may need to access the DDS 72 to determine how the data is stored in the FMS database 40. For example, in some instances, the database 40 stores parameter values, such as past parameter values in order to, for example, mimic the state of a device. Consequently, the FMS database interface 80 may have to access the DDS 72 to retrieve this information to know what type of data is stored in the database, i.e., integer, enumerated, etc. However, information stored in the database 40 need not be stored in a DDL format. Therefore, to service a command from the server 70 to read data from, or write data to, the database 40, the FMS database interface 80 may not need to access the DDS 72 for device values. Instead, the FMS database interface 80 may write data to, and read data from, the database 40 directly.

The FMS database interface 80 is preferably an application program interface (API) of any conventional type which is specifically set up and configured for retrieving information from the database 40 according to any desired or known method. Thus, the FMS database interface 80 automatically keeps track of where and how data is stored in, and retrieved from the database 40.

As indicated above, the current application 56 and, if desired, the interface block 58 can also interface with the database 40 through the FMS database interface 62 and the ODBC block 64. The FMS database interface 62 may comprise any desired or known applications program interface (API) having a library of routines developed to convert data and requests from a format recognizable or used by the current application 56 into a form recognizable and usable by the ODBC block 64 and vice-versa. Using the FMS database interface 62 (API) to write to the database 40, as opposed to using the ODBC block 64 directly, helps maintain database integrity and consistency and makes applications easier to write because the application is then shielded from database management. Typically, the FMS database interface 62 and the ODBC block 64 (or any other open database accessing system) will be used when an application needs to store data in the database 40 in a format that is inaccessible or incompatible with the OLE object hierarchy communication scheme discussed herein.

FIGS. 3 and 4 illustrate a particular hierarchy of OLE objects which has been developed to represent all of the information defined within or available from one or more DDL's, a set of smart devices which follow the protocols of those DDL's and a database which stores information related to devices using those DDL's. The hierarchy of FIGS. 3 and 4 also represents the relationships between those OLE objects. This hierarchy can be used within an OLE environment to enable an application to retrieve information associated with a DDL, smart devices which use that DDL, and a database which stores information pertaining to smart devices which use that DDL. Thus, the hierarchy of FIGS. 3 and 4 represents not only an arrangement of DDL information (i.e., information available from DD's of DDL's and/or information available from a device or a database associated with devices using one or more DDL's), but also a way of defining an interface between the DCI 60 and the servers 68 and 70 of FIG. 2 in order to access, retrieve, and change this information.

Each of the OLE objects in the hierarchy of FIGS. 3 and 4 is preferably an OLE automation object and is represented as an oval having the type of OLE object identified therein. Each of the OLE objects of FIGS. 3 and 4 includes, or is associated with, a subset of the information defined within or used by one or more DDL's and available from DD's, smart devices and databases which store information pertaining to smart devices.

Generally, each of the OLE automation objects of FIGS. 3 and 4 includes properties (or attributes), methods and interfaces. Because the OLE objects within FIGS. 3 and 4 are automation objects, they have an IDispatch interface (a well-known interface of the OLE protocol) associated therewith. The IDispatch of the OLE automation objects of FIGS. 3 and 4 can be used by, for example, the DCI 60 and the server network 66 to retrieve information pertaining to the properties and the methods of that OLE object and to communicate with other OLE objects.

The properties of an OLE object comprise data pertaining to the objects. Each property also has functions which can be used, for example, to get the property value and to set the property value of the OLE object. Example OLE object properties include the name of the object, a count of the number of items within or associated with the object, a label associated with the object, and help associated with the object.

OLE object methods perform actions on OLE objects, or on the data in OLE objects, implement particular routines using the data in OLE objects, and communicate with other OLE objects. For example, a method may enumerate a set of values in other OLE objects. Together, the properties and the methods of an OLE automation object define the programmable interface of that OLE object accessible by the server network 66 and the DCI 60.

The hierarchy of FIGS. 3 and 4 comprises an upper hierarchy, illustrated in FIG. 3, and a lower hierarchy, illustrated in FIG. 4. The upper hierarchy of FIG. 3 corresponds to and illustrates the physical or defined connectivity of devices such as HART, Fieldbus, and other smart or conventional devices, and blocks, such as Fieldbus blocks, connected within a process. The lower hierarchy of FIG. 4 illustrates relationships among the data which is available from, or referenced by, DDL's such as the HART and Fieldbus DDL's, and the data which is stored in and/or available from DD's, smart devices and/or a database pertaining to smart or other devices.

In order to facilitate a complete understanding of the hierarchy of FIGS. 3 and 4, a table (entitled "OLE Object DDL Equivalents") is provided at the end of the present specification. The OLE Object DDL Equivalents table identifies, for each of the OLE objects illustrated in the lower hierarchy of FIG. 4, the functionally equivalent data, definitions and/or constructs of the Fieldbus DDL that correspond to the OLE object. It should be recognized, however, that the OLE objects of FIGS. 3 and 4 similarly have functionally equivalent types of data, definitions, and constructs available in other DDL's, such as the HART DDL, and that the hierarchy of FIGS. 3 and 4 therefore can be applied to any DDL. Another table (entitled "OLE Object Definitions"), also appearing at the end of the present specification, provides a list of some important properties and methods associated with each of the OLE objects illustrated in FIGS. 3 and 4, and provides a short description of those properties and methods.

Once again, the properties of the OLE objects of FIGS. 3 and 4 represent, and correspond to, similar types of data available from, or defined by, DDL's (for example, the HART and Fieldbus DDL's) because, as noted above, the OLE objects of FIGS. 3 and 4 have been developed to map onto and represent the data available from or defined by these DDL's. Thus, for example, the Block object of FIG. 3 represents and corresponds to the block entity recognized and used by the Fieldbus DDL, while the Device object of FIG. 3 and the Parameter object of FIG. 4A represent and correspond to the device and parameter entities, respectively, recognized and used by both the HART and Fieldbus DDL's. The methods identified in the OLE Object Definitions table are standard OLE methods.

Each OLE object within the hierarchy of FIGS. 3 and 4 can be accessed or defined by traversing a path through the hierarchy to that OLE object. Beginning at the top of FIG. 3, every path through the hierarchy of FIGS. 3 and 4 includes a Root object. Root objects define, among other things, the ViewTime to which the data within any of the OLE objects below the Root object pertains. More specifically, the Root object is associated with a ViewTime, which may be "past," "present," or "future" and, in some instances, which specifies a particular time. If the ViewTime is present, the time is the actual time. If the ViewTime is past, the time may be set to any historical time but, preferably, is set to a time at which a change was made to one or more parameter values. Preferably these changes are stored in the database 40 in, for example, an event log. If the ViewTime is future, the time may be set to any future time or may be set to indicate only that it refers generally to the future.

The Item method of the Root object includes a set of collections, as identified in the OLE Object Definitions table, which defines the next layer in the hierarchy of FIG. 3. Generally, the collections of the Item method of an OLE object define interconnections between that OLE object and the OLE objects below that OLE object within the hierarchy of FIGS. 3 and 4. Each collection of an Item method of an OLE object is illustrated in the hierarchy of FIGS. 3 and 4 by the quoted name of that collection below the OLE object which includes that collection. The generic name of the members within a collection are identified in the hierarchy of FIGS. 3 and 4 by unquoted and underlined expressions located beneath the OLE object associated with the collection type and above the OLE object which has information pertaining to this expression as one of the properties thereof.

Thus, for example, the Root object has a collection of BlockTag objects (identified as the "BlockTag" collection), each of which has a particular name illustrated generally in FIG. 3 as Block Tag. Generally, a block tag is a unique identifier assigned to a particular block within the FMS system by a technician installing/configuring the FMS system in order to identify a particular block. A BlockTag object having a name of Block Tag, therefore, uniquely defines a Block object, as illustrated in FIG. 3. As is evident, the actual number of BlockTag objects within the hierarchy of FIGS. 3 and 4 is dependent on the number of blocks (as that name is used in the Fieldbus DDL protocol) connected to or associated with the FMS system 10.

The PhysicalTag, DeviceID, and DeviceTag objects relate to or are associated with the "PhysicalTag," "DeviceID," and "DeviceTag" collections of the Root object, respectively, and are used to uniquely define a particular device connected to or associated with the FMS system 10. A device ID typically includes a triplet of information comprising the name of the device manufacturer, the model number of the device, and the serial number of the device. Device tags and physical tags usually refer to a location of the device in a plant or a process such as the process 12. The value of a physical tag and/or a device tag can be, for example, an alphanumeric code associated with a specific physical location in the plant or any other description of a physical location. For HART devices, the physical tag is considered the same as the device tag whereas, for Fieldbus devices, the physical tag can have a different value than the device tag. The OLE objects in FIGS. 3 and 4 immediately below a quoted collection name, such as the PhysicalTag object, the DeviceTag object, and the DeviceID object, are also referred to as collections because they are related to constructs which a DDL considers or defines as collections.

In lieu of, or in addition to having a device tag, a physical tag and/or a device ID, a device can be identified by its physical communication connection to an FMS system. Specifically, each device is connected to an FMS network (illustrated in FIG. 3 by the Network object which is a "Net" collection of the Root object) through one of a number of networks, each of which is identified generically by the expression TCP/IP Node Name.

Each network includes a series of nodes, identified in FIG. 3 by the NetNode object. A network node includes a set of ports (illustrated by the Port object) which may have names of, for example, "Com1" or "Com2". The port may connect to a device through a modem (identified by the Modem object) and at one of sixteen station addresses, each of which is identified by a different Station Address.

The port of a network node may also connect to a device through one or more HART interface units (HIU's) (identified by an HIU object) having a Station Address. Each HIU includes one or more interchanges (identified by the Interchange object) each of which typically includes 8 lines identified by Line Number. Interchange objects also include a method (which, contrary to the above-stated general rule about quoted names, is identified by the label "Block") which returns an interface to the particular Block object that describes the HIU.

A network node can also be coupled to a device through one or more different DCS's, for example, the RS3, Provox, or other DCS's. Although FIG. 3 illustrates each of these as connected through a generic DCS object, the actual connection to an RS3 DCS, for example, would be made and could be identified in FIG. 3 by a node number, a card number, a port (typically one of four ports in a card) and a line (typically four lines per port). However, because the configurations of these DCS systems are not yet fully developed, the actual connections with each are not shown and the DCS object is not mentioned in the OLE Object Definitions table.

Furthermore, a network node may be coupled to one or more Fieldbus interface cards. However, because the Fieldbus devices are not yet being sold, the exact connection to a device is not yet known and, therefore, this connection is not represented in the hierarchy of FIG. 3. However, such a Fieldbus connection could easily be added by showing a Fieldbus object and any other OLE objects related to the components required for a Fieldbus connection from between a network node and a device between the NetNode object and the Device object.

Once a device is identified in any manner specified above, a block within the device can be uniquely determined by the "Tag" collection, illustrated as the Tag object, having the HART Tag name. If the device is a HART device, the contents of which are represented by only one conceptual block, the block is already uniquely identified and can simply be specified by the "HART" collection. The names of the tags related to the Tag object are specified as HART Tag in FIG. 3 because the HART tag of HART devices is used as this identifier. However, other tags for other types of devices could be used instead.

As suggested above, a Block object and, correspondingly, a block of a process, can be uniquely identified by traversing any of the above defined paths through the upper hierarchy of FIG. 3. Likewise, every other OLE object within the hierarchy of FIGS. 3 and 4 can be identified by a unique moniker derived by traversing a path from the Root object at the top of the hierarchy of FIG. 3 through to the particular OLE object. Thereafter, the properties and methods of any of the OLE objects within the hierarchy of FIGS. 3 and 4 can be referenced and obtained using the moniker developed for that OLE object.

More particularly, a moniker can be determined from the hierarchy of FIGS. 3 and 4 by compiling a string comprising the quoted and the unquoted/underlined expressions encountered in traversing a path from the Root object in FIG. 3 to the OLE object of interest, and separating these expressions with an exclamation point ("|"). For example, the moniker for a Block object can be any of the following:

Root|BlockTag|Block Tag|

Root|PhysicalTag|HART Tag|Tag|HART Tag

Root|DeviceID|Unique Identifier|HART

Root|Net|TCP/IP Node Name|Port

Name|Modem|Station Address|Tag|HART Tag

As will be evident, monikers for other OLE objects illustrated in FIGS. 3 and 4 can be developed using this format. The "NamedConfig" collection of the Root object of FIG. 3 (represented by the NamedConfigs object) relates to objects which are stored in the FMS database 40 and which are not available from a device. Each NamedConfigs object is identified by a ConfigName to specify a particular NamedConfig object. A NamedConfig object may include, for example, a "recipe" or particular configuration of a block necessary for implementing a particular function within a process, a past configuration of a block within a process, or for that matter, any other desired user information related to Block objects. However, to the server network 66 of FIG. 2, each NamedConfig object looks similar to a Block object except that the parameter value data of a NamedConfig object is retrieved from the FMS database 40 as opposed to being retrieved from a device. NamedConfig objects may have a subset of the information typically associated with a Block object.

The lower hierarchy of FIG. 4 illustrates an inter-relationship among the data associated with each block of a system. Therefore, as illustrated in FIG. 4, each Block object (and each NamedConfig object) includes a set of collections denominated "Param," "Unit," "Database," "Refresh," "ItemArray," "Collection," "Menu," "Method," "EditDisplay," and "WAO," each having an associated (although slightly differently named) OLE object. Each of these OLE objects, in turn, have other OLE objects related thereto as defined in FIG. 4. Thus, for example, a Parameter object identified by a Param Name may be a VariableParameter object, a RecordParameter object or an ArrayParameter object. If it is a VariableParameter object, it includes collections of "IndexedItemArray," "Enum," "PreEdit," and "PostEdit," all having associated OLE objects. The EnumerationValues object (a collection of the VariableParameter object for variables of the enumerated type) has particular enumerated values identified by the Enumeration Value object which, in turn, includes a collection of Method objects. These Method objects may, for example, include methods of getting or changing enumerated values of a VariableParameter object.

The property, data, and methods stored in, or associated with, all of the OLE objects within FIG. 4, except for the DatabaseParameters and DatabaseParameter objects, represent information which is available from or through the use of DD's or a device conforming to a DDL. The data and method of the DatabaseParameters objects and DatabaseParameter objects are stored in a database.

As with FIG. 3, any OLE object in FIG. 4 can be uniquely identified by a moniker developed by tracing a path from the Root object of FIG. 3 down to the particular OLE object of interest. Thus, for example, the moniker for a pre-edit Method block could be constructed by adding onto the end of the moniker for any Block object of FIG. 3, which is also represented by the Block object of FIG. 4, the expression |param|Param Name|PreEdit|Index.

Once a moniker is established for a particular object within the hierarchy of FIGS. 3 and 4 and stored in the memory associated with the server network 66, the DCI 60 and the server network 66 can, thereafter, operate on and access that OLE object using a shorter unique "handle" generated by the server network 66. The handle may, for example, comprise a unique number identifying an OLE object which has been stored in the memory of the server network 66.

In essence, with a unique moniker or the handle, any OLE object identified by the hierarchy of FIGS. 3 and 4 can be immediately accessed by the DCI 60 or the server network 66 and the methods within that OLE object can be invoked in order to accomplish communication with the DDS, a database, a smart device, or other OLE objects as necessary. Thus, for example, the software routine within the server 68 which accesses the DDS 72 to retrieve a particular parameter value from a particular device can be initiated when a call to the proper VariableParameter object is initiated by the DCI 60 using a command which tells the OLE VariableParameter object to read a parameter value.

As is evident, the server network 66 communicates with the database 40, the DDS 72, and the on-line devices transparently to the DCI 60 and the current application 56, because the server network automatically accesses the interrelationships between the OLE objects identified by the lower hierarchy of FIG. 4 to determine which set of routines to implement in order to obtain new information requested by an OLE object or a DDS.

It should be noted that, for any OLE object of FIGS. 3 and 4 to be accessed, the OLE objects above that OLE object in at least one path between that OLE object and the Root Object FIG. 3 must be stored in the server network memory. Thus, for example, when accessing a VariableParameter object of a parameter for a block, the Parameter object and the Block object associated with that parameter and that block will also be stored in the server network memory. The Device object, the DeviceID object and the Root object may also be stored in the server network memory. Without these higher level objects, the server network 66 can not access enough information to determine how to locate and retrieve the data of the VariableParameter object.

In a typical situation, the DCI 60 sends a command to get a value from an OLE object, for example, the Handling property of a VariableParameter object for a particular block of a particular device using a moniker or a handle which has been provided for that VariableParameter object. If the identified OLE object has not yet been stored in the memory of the server network 66, the server network 66 uses pre-written routines and the methods of the one or more OLE objects above that VariableParameter object to retrieve this data from, for example, one of the DDS 72, the smart device itself, or the database 40. The server network 66 then stores this data in a server memory. If needed the server network 66 first stores for example, the Root object, the DeviceID object, the Device object, the Block object, and the Parameters object, in memory.

Next, the server uses the methods of the VariableParmeter object and pre-written routines associated therewith to access the DDS 72 (because that is where the Handling information of a variable parameter of a block is located). If, as in this instance, the value of the Handling property of the variable parameter depends on the mode parameter to which the smart device is currently set, the DDS returns a message to the server 68 telling the server 68 that the DDS needs the mode parameter information pertaining to the device or block which contains that variable. At this point, the server 68 locates the Device object related to the VaribleParameter object to determine how to communicate with the device, i.e., where the device is located in the system and how to interact with that device. The server 66 then uses a prewritten routine for communicating with the device associated with the Device object to instruct the smart device communication interface 74 to retrieve the mode parameter of the device. When the smart device communication interface 74 returns the mode parameter value to the server 68, the server 68 provides this information to the DDS 72 which, thereafter, computes and returns the Handling property to the server 66 which then forwards this information to the OLE VariableParameter object and, thereby to the DCI 60 (because changes in OLE objects result in messages being sent to the host, i.e., the DCI 60 in this case). Thus, to the DCI 60, it merely appears that a request for a read of the Handling property of a parameter was sent to an OLE object and that a message was returned with the Handling property. The communication with the DDS and between OLE objects was accomplished automatically by the server transparently to the current application 56, and the application did not need to know any specifics regarding the type of device was accessed, the DD or DDL associated with that device, etc. Thus, using the interface defined above, an application can communicate with a number of different smart devices following the same or different DDL protocols without the need to consider any of the specifics of the DDS, DDL or DD which must be used to implement that communication.

As will be apparent to those skilled in the art, the DCI 60 may thereby operate to communicate with and retrieve information from the OLE hierarchy represented by FIGS. 3 and 4 by performing relatively simple routines which, for example, (1) create an object hierarchy and associate it with the server network 66, (2) traverse the object hierarchy to explore the objects below a specified object, (3) implement standard OLE methods like Item, which traverses a specific path from one object to another, and NewEnum, which creates an interface to enumerate objects one level below, (4) implement methods related to Block objects which may include methods related to DDL operations, (5) read and write Root and Device object properties, (6) initiate and control non-blocking read and write requests from OLE objects, (7) retrieve results from blocking reads and writes, (8) control changes to the database 40, and (9) control the creation and maintenance of an event log that includes information pertaining to, for example, user changes to the system including change times, identification of the persons and the computers which made the changes, etc.

As a result, an application for the FMS system 10 does not have to be specifically programmed to interface with a DDS, database or smart devices which, in turn, allows an application developer to be much less knowledgeable with respect to DDL formats, DD's and smart device communications.

It will be noted that, using the hierarchy of FIGS. 3 and 4 as described above, any application implemented by the FMS system 10 can interface with FMS devices using, for example, any OLE-compatible programming environment to gain access to the IUnknown and IDispatch interfaces associated with each object in the hierarchy. It is considered that Visual Basic programs and C++ programs are well-suited to use the above-defined OLE hierarchy.

Furthermore, although the hierarchy of FIGS. 3 and 4 is specifically related to the Fieldbus DDL and to the HART DDL, which is very similar to the Fieldbus DDL, it is considered that this or a similar hierarchy can be made for other DDL's associated with other smart devices including, for example, Modbus smart devices in accordance with the present invention. Furthermore, it is considered that the hierarchy of FIGS. 3 and 4 can be implemented by other object-oriented programming protocols and even by non-object oriented programming protocols.

While the present invention has been described with reference to specific examples, which are intended to be illustrative only, and not to be limiting of the invention, it will be apparent to those of ordinary skill in the art that changes, additions and/or deletions may be made to the disclosed embodiments without departing from the spirit and scope of the invention.

OLE OBJECT DDL EQUIVALENTS

    ______________________________________
    The following table explains the correspondence between
    the OLE hierarchy described above and the related constructs in
    the DDL. As used in the table, the term "Host device" means an
    FMS system or an FMS application. Further, the actual keywords
    employed by a particular DDL may vary, and the proper keywords
    for a particular DDL will be provided in the specification
    provided for that DDL. The following table is based on the
    Fieldbus Device Description Language, which is similar to the
    HART Device Description Language.
    OLE OBJECT (Lower Hierarchy)
                     DDL EQUIVALENT
    ______________________________________
    ArrayParameter object
                     The DDL equivalent is an array,
                     which is a logical group of
                     values. Each value, or element,
                     is of the data type of a DDL
                     variable. An element may be
                     referenced from elsewhere in the
                     device description via the array
                     name and the element index. DDL
                     arrays describe communication
                     array objects. Therefore, from
                     a communication perspective, the
                     individual elements of the array
                     are not treated as individual
                     variables, but simply as
                     individual values.
    Block object     The DDL equivalent is a block,
                     which defines the external
                     characteristics of a DDL block.
    Collection object
                     The DDL equivalent is a
    This OLE object represents a
                     collection, which is a logical
    particular object in the
                     group of members. Each member
    Collections collection
                     in the group is assigned a name.
    object.          The members may be referenced in
    (see Collections)
                     the device description by using
                     a collection name and a member
                     name.
    CollectionItems collection
                     The DDL equivalent is a
    object ("Member")
                     collection, which is a logical
                     group of members. Each member
                     in the group is assigned a name.
                     The members may be referenced in
                     the device description by using
                     a collection name and a member
                     name.
    Collections collection object
                     The closest DDL equivalent is a
    ("Collection")   collection, which is a logical
                     group of items (in this case
                     collections). Each collection
                     in the group is assigned a name.
                     The collections may be
                     reference from in the device
                     description by using the
                     collection name and the name of
                     the collection of collections.
    DatabaseParameters collection
                     There is no DDL equivalent to
    object ("Database")
                     this OLE collection object,
                     which exists only in the FMS
                     database. This object relates
                     to a collection of parameters
                     stored in a database.
    DatabaseParameter object
                     There is no DDL equivalent to
                     this OLE object, which exists
                     only in the FMS database. This
                     object relates to a parameter
                     stored in a database.
    EditDisplay object
                     The DDL equivalent is an edit
                     display, which defines how data
                     will be presented to a user by a
                     host. It is used to group items
                     together during editing.
    EditDisplayItems collection
                     The DDL equivalent is a
    object ("Display" and "Edit")
                     collection of edit items, which
                     are a set of block parameters
                     and elements of block parameters
                     to be edited by the user. The
                     display items are provided to
                     allow the user to decide what
                     the values of the edit items
                     should be.
    EditDisplays collection
                     The DDL equivalent is a
    object ("EditDisplay")
                     collection of edit displays,
                     which define how data will be
                     presented to a user by a host.
                     They are used to group items
                     together during editing.
    Elements collection object
                     The DDL equivalent is a
    ("Element")      collection or group of elements,
                     which specify one item (such as
                     a variable or menu) in the
                     group, and is defined by a group
                     of four parameters (index, item,
                     description and help).
    EnumerationValue object
                     The DDL equivalent is a variable
                     of the enumeration type. Such
                     variables include enumerated
                     variables, which are unsigned
                     integers that have a text string
                     associated with some or all
                     values (useful for defining
                     tables, for example), and bit-
                     enumerated variables, which are
                     unsigned integers that have a
                     text string associated with some
                     or all bits (useful in defining
                     status octets).
    EnumerationValues collection
                     The DDL equivalent is a
    Object ("Enum")  collection of variables of the
                     enumeration type.
    ItemArray collection object
                     The DDL equivalent is a
    ("IndexedItemArray")
                     collection of item arrays.
    ItemArray object The DDL equivalent is an item
                     array, which is a logical group
                     of items, such as variables or
                     menus. Each item in the group
                     is assigned a number, called an
                     index. The items can be
                     referenced from elsewhere in the
                     device description via the item
                     array name and the item number.
                     Item arrays are merely groups of
                     DDL items and are unrelated to
                     communication arrays (item type
                     "ARRAY"). Communication arrays
                     are arrays of values.
    ItemArrayItems collection
                     The DDL equivalent is an
    object ("Element")
                     element, an attribute of an item
                     array which identifies elements
                     of the item array. Each item
                     array element specifies one item
                     (such as a variable or menu) in
                     the group, and is defined by a
                     group of four parameters (index,
                     item, description and help).
    ItemArrays collection object
                     The DDL equivalent is a
    ("ItemArray")    collection of item arrays.
    Members collection object
                     The DDL equivalent is a
    ("Member")       collection of members, which are
                     variables, records, and/or
                     arrays.
    Menu object      The DDL equivalent is a menu,
                     which organizes parameters,
                     methods, and other items
                     specified in the DDL into a
                     hierarchical structure. A host
                     application may use the menu
                     items to display information to
                     the user in an organized and
                     consistent fashion.
    MenuItems collection object
                     The DDL equivalent is a
    ("MenuItem")     collection of menus items. The
                     items of a menu specify the
                     items associated with the menu
                     plus an optional qualifier.
    Menus collection object
                     The DDL equivalent is a
    ("Menu")         collection of menus.
    Method object    The DDL equivalent is a method,
                     which describes the execution of
                     complex interactions that must
                     occur between host devices and a
                     field device.
    Methods collection object
                     The DDL equivalent is a
    ("PreEdit", "PostEdit", and
                     collection of methods.
    "Method")
    NamedConfig object
                     There is no DDL equivalent to a
                     NamedConfig object because these
                     objects correspond to blocks
                     that are stored in the FMS
                     database rather than in field
                     devices.
    Parameters collection object
                     The DDL equivalent is a
    ("Param")        collection of parameters, which
                     may be records, arrays, or
                     variables.
    RecordParameter object
                     The DDL equivalent is a record,
                     which is a logical group of
                     variables. Each variable in the
                     record is assigned a DDL
                     variable name. Each variable
                     may have a different data type.
                     The variables may be referenced
                     from elsewhere in the device
                     description via the report name
                     and the member name. DDL
                     records describe communication
                     record objects. Therefore, from
                     a communication perspective, the
                     individual members of the record
                     are not treated as individual
                     variables, but simply as a group
                     of variable values.
    RefreshRelation object
                     The DDL equivalent is a refresh
                     relation, a particular type of
                     relation which allows the host



                     device to make decisions
                     regarding parameter value
                     consistency when a parameter
                     value changes. It specifies a
                     set of block parameters which
                     may need to be refreshed (re-
                     read from the device) whenever a
                     block parameter from another set
                     is modified. A block parameter
                     can have a refresh relationship
                     with itself, implying that the
                     block parameter must be read
                     after writing.
                     Occasionally writing a block
                     parameter to a field device
                     causes the field device to
                     update the values of other block
                     parameters. If the additional
                     updated block parameters are
                     dynamic, there is no conflict
                     because the host device should
                     re-read the parameter values
                     from a failed device each time
                     the values are needed. However,
                     host devices may cache the
                     values of static block
                     parameters. Therefore, for host
                     devices to maintain the correct
                     values of all static block
                     parameters, they need to know
                     when the field device is
                     changing its values.
    RefreshRelations collection
                     The DDL equivalent is a
    object ("Refresh")
                     collection of refresh relations.
    RelationItems collection
                     The DDL equivalent is a
    object ("Units", "Members",
                     collection of parameters, which
    "Left", and "Right")
                     may be variables, records,
                     and/or arrays.
    ResponseCode object
                     The DDL equivalent is a response
                     codes, which specifies the
                     values a field device may return
                     as application-specific errors.
                     Each variable, record, array,
                     variable list program, or
                     domain can have its own set of
                     response codes, because each one
                     is eligible for FMS services.
    ResponseCodes collection
                     The DDL equivalent is a
    object ("RespCode")
                     collection of response codes.
    UnitRelation object
                     The DDL equivalent is a unit
                     relation, which specifies a
                     units code parameter and the
                     block parameters with those
                     units. When a units code
                     parameter is modified, the block
                     parameter having that units
                     code should be refreshed. In
                     this respect, a unit relation is
                     exactly like a refresh relation.
                     In addition, when a block
                     parameter with a units code is
                     displayed, the value of its
                     units code will also be
                     displayed.
    UnitRelations collection
                     The DDL equivalent is a
    object ("Unit")  collection of unit relations.
    VariableParameter object
                     The DDL equivalent is a
                     variable, which describes data
                     contained in a device.
    WriteAsOne Relation object
                     The DDL equivalent is a write-
                     as-one relation, which informs
                     the host device that a group of
                     block parameters needs to be
                     modified as a group. This
                     relation does not necessarily
                     mean the block parameters are
                     written to the field device at
                     the same time. Not all block
                     parameters sent to the field
                     device at the same time are
                     necessarily part of a write-as-
                     one relation. If a field device
                     requires specific block
                     parameters to be examined and
                     modified at the same time for
                     proper operation, a write-as-one
                     relation is required.
    WriteAsOneRelations
                     The DDL equivalent is a
    collection object ("WAO")
                     collection of write-as-one
                     relations.
    ______________________________________

    ______________________________________
    The following tables illustrate the properties and methods
    of the various OLE objects and collection objects in the lower
    hierarchy illustrated in FIG. 4. The various properties of
    those objects and collection objects are not included in the
    following table, but those properties correspond to the
    attributes of the DDL objects which are equivalents of the
    objects. The DDL equivalents of the OLE objects and collection
    objects are identified in the OLE object DDL equivalents table,
    and are fully described in the ISP Fieldbus DDL specification
    document, incorporated by reference herein.
    The following tables use the following symbols to denote
    the following information:
    (R)     Access the property via the Read/Write and Get/Set
            methods.
    (.dagger.)
            Read/Write.
    (.dagger..dagger.)
            Read/Write in devices less than Rev. 5; otherwise,
            read-only.
    (M)     Run this method by executing the OLE method called
            "Method" or "CallMethod"
    (N)     Not implemented.
    (C)     Access this property via an OLE property. Get
            method, or a Read request containing only this
            property.
    The values referenced in the Return Type column indicate
    the following VARIANT types:
    VT.sub.-- EMPTY
                  Used when no value is available.
    VT.sub.-- I4  Used for integer values and boolean
                  values.
    VT.sub.-- R4  Used for most floating point field
                  measurement values.
    VT.sub.-- R8  Used for double precision measurement
                  values.
    VT.sub.-- DATE
                  Used for dates and times using double
                  precision.
    VT.sub.-- BSTR
                  Used for character strings.
    VT.sub.-- ERROR
                  Used for error codes.
    VT.sub.-- ARRAY
                  Used for binary values.
    All objects defined in this table have the set of Standard
    Properties listed below.
    ______________________________________

    ______________________________________
    Property Name
                 Return Type
                            Description
    ______________________________________
    Kind (R)     VT.sub.-- I4
                            Returns the object's kind.
    KinAsString (R)
                 VT.sub.-- BSTR
                            Returns the object's kind as a
                            string.
    Moniker (P)  VT.sub.-- BSTR
                            Returns a full moniker for the
                            object.
    ______________________________________

    ______________________________________
    Property Name
               Return Type Description
    ______________________________________
    Count (C)  VT.sub.-- I4
                           The number of items in the
                           collection. This property
                           blocks until all the items in
                           the collection can be accessed
                           without blocking.
    ReadyCount (C)
               VT.sub.-- I4
                           The number of items in the
                           collection that can be
                           accessed without blocking,
                           which may be less than the
                           total number of items in the
                           collection.
    ServerCount (N)
               VT.sub.-- I4
                           Same as the Count property
                           except it does not block if
                           all the items are not
                           immediately available.
    Name (R)   VT.sub.-- BSTR
                           The parameter's (or record
                           member's) name.
    MemberId (R)
               VT.sub.-- I4
                           The parameter's (or record
                           member's) member ID.
    ItemId (R) VT.sub.-- I4
                           The array's item ID;
    ParamIndex (R)
               VT.sub.-- I4
                           The parameter's (or array
                           element's) index.
    ParamLabel (R)
               VT.sub.-- BSTR
                           The parameter-specific label.
    Label (R)  VT.sub.-- BSTR
                           The array-specific label.
    ParamHelp (R)
               VT.sub.-- BSTR
                           The parameter-specific help.
    Help (R)   VT.sub.-- BSTR
                           The array-specific help.
    NumberOfElements
               VT.sub.-- I4
                           The number of elements in the
    (R)                    array.
    ______________________________________
    Method Name
               Return Type Description
    ______________________________________
    Item       VT.sub.-- DISPATCH
                           Takes one argument of type
                           VT.sub.-- BSTR and returns one of
                           the collections provided by the
                           object.
                           Collections:
                           The "Element" collection is an
                           Elements collection and
                           contains the array's elements.
                           The "RespCode" collection is a
                           ResponseCodes collection and
                           contains the array's response
                           codes.
    .sub.-- NewEnum
               VT.sub.-- UNKNOWN
                           Returns the IUnknown interface
                           of an object that implements
                           the IEnumVariant interface.
    ______________________________________

    ______________________________________
               Return
    Property Name
               Type        Description
    ______________________________________
    Count (C)  VT.sub.-- I4
                           The number of items in the
                           collection. This property
                           blocks until all the items in
                           the collection can be accessed
                           without blocking.
    ReadyCount (C)
               VT.sub.-- I4
                           The number of items in the
                           collection that can be accessed
                           without blocking, which may be
                           less than the total number of
                           items in the collection.
    ServerCount (N)
               VT.sub.-- I4
                           Same as the Count property
                           except it does not block if all
                           the items are not immediately
                           available.
    Name (R)   VT.sub.-- BSTR
                           The block's name.
    ItemId (R) VT.sub.-- I4
                           The block's item id.
    Label (R)  VT.sub.-- BSTR
                           The block's label.
    Help (R)   VT.sub.-- BSTR
                           The block's help.
    Tag (R)    VT.sub.-- BSTR
                           The block's internal tag.
                           Note:
                           For a HART block, this is the
                           HART tag.
    BlockTag (R)
               VT.sub.-- BSTR
                           The block's external tag.
    PhysicalTag (R)
               VT.sub.-- BSTR
                           The internal tag of the device
                           in which the block resides.
                           Note:
                           For a HART device, this is the
                           HART tag.
    DeviceTag (R)
               VT.sub.-- BSTR
                           The external tag of the device
                           in which the block resides.
    DeviceId (R)
               VT.sub.-- BSTR
                           The unique identifier of the
                           device in which the block
                           resides.
    NetAddress (R)
               VT.sub.-- BSTR
                           The network address, as a
                           moniker, of the device in which
                           the block resides.
    StationAddress (R)
               VT.sub.-- I4
                           The station address of the
                           device in which the block
                           resides.
    ______________________________________
    Method Name
               Return Type Description
    ______________________________________
    Item       VT.sub.-- DISPATCH
                           Takes one argument of type
                           VT.sub.-- BSTR and returns one of
                           the collections provided by the
                           object.
                           Collections:
                           The "Param" collection is a
                           Parameters collection and
                           contains the block's
                           parameters.
                           The "Database" collection is a
                           DatabaseParameters collection
                           and contains the database
                           parameters for the block.
                           The "Method" collection is a
                           Methods collection and
                           contains the block's methods.
                           The "Menu" collection is a
                           Menus collection and contains
                           the block's menus.
                           The "EditDisplay" collection
                           is an EditDisplays collection
                           and contains the block's edit
                           displays.
                           The "ItemArray" collection is
                           an ItemArrays collection and
                           contains the block's item
                           arrays.
                           The "Collection" collection is
                           a Collections collection and
                           contains the block's
                           collections.
                           The "Refresh" collection is a
                           RefreshRelations collection
                           and contains the block's
                           refresh relations.
                           The "Unit" collection is a
                           UnitRelations collection and
                           contains the block's unit
                           relations.
                           The "WAO" collection is a
                           WriteAsOneRelations collection
                           and contains the block's write
                           as one relations.
    .sub.-- NewEnum
               VT.sub.-- UNKNOWN
                           Returns the IUnknown interface
                           of an object that implements
                           the IEnumVariant interface.
    Invalidate (M)
               VT.sub.-- EMPTY
                           Invalidates the parameters in
                           the parameter cache. This
                           method is used to force all
                           the parameters to be re-read
                           from the device.
    SendCommand (M)
               VT.sub.-- EMPTY
                           Sends a HART command. Takes
                           two arguments of type VT.sub.-- I4
                           which specify the command
                           number and the transaction
                           number.
    SendContinuous
               VT.sub.-- EMPTY
                           Sends two HART commands
    Command (M)            continuously. Takes six
                           arguments of type VT.sub.-- I4. The
                           first three arguments specify
                           the first command to be sent
                           and the last three arguments
                           specify the second command to
                           sent. The first and fourth
                           arguments specify command
                           numbers, the second and fifth
                           arguments specify transaction
                           numbers, and the third and
                           sixth arguments specify the
                           number of times to send the
                           specified commands.
    FindResponseCode
               VT.sub.-- BSTR
                           Returns the string associated
    (M)                    with a response code of a HART
                           command. Takes three argu-
                           ments of type VT.sub.-- I4 which
                           specify the command number,
                           the transaction number and the
                           response code value.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (N) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (N)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          accessed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          items in the collection.
                          The Block object whose
                          BlockTag property matches the
                          argument is returned.
    .sub.-- NewEnum (N)
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interface
                          of an object that implements
                          the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (C) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (C)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          accessed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          items in the collection.
                          If the argument begins with a
                          $, the rest of the string must
                          take the form of an integer.
                          The DDL collection whose
                          ItemId property matches the
                          argument is returned.
                          If the argument begins with a
                          digit, the string must take
                          the form of an integer and the
                          DDL collection whose Index
                          property matches the argument
                          is returned.
                          Otherwise, the DDL collection
                          whose Name property matches
                          the argument is returned.
    .sub.-- NewEnum
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interface
                          of an object that implements
                          the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (C) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (C)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          accessed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          items in the collection.
                          If the argument begins with a
                          $, the rest of the string must
                          take the form of an integer.
                          The item whose ItemMemberID
                          property matches the argument
                          is returned.
                          Otherwise, the item whose
                          ItemName property matches the
                          argument is returned.
    .sub.-- NewEnum
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interface
                          of an object that implements
                          the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
               Return Type  Description
    ______________________________________
    ItemName (R)
               VT.sub.-- BSTR
                            The collection item's member
                            name.
    ItemMemberId (R)
               VT.sub.-- I4 The collection item's member
                            ID.
    ItemLabel (R)
               VT.sub.-- I4 The collection item's label.
    ItemHelp (R)
               VT.sub.-- BSTR
                            The collection item's help.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (C) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (C)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          accessed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    Name (R)  VT.sub.-- BSTR
                          The collection's name.
    ItemId (R)
              VT.sub.-- I4
                          The collection's item ID.
    Index (R) VT.sub.-- I4
                          The collection's index.
    Label (R) VT.sub.-- BSTR
                          The collection's label.
    Help (R)  VT.sub.-- BSTR
                          The collection's help.
    Type (R)  VT.sub.-- I4
                          The collection's type.
    TypeAsString (R)
              VT.sub.-- BSTR
                          The collection's type as a
                          string.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          collections provided by the
                          object.
                          Collections:
                          The "Member" collection is a
                          CollectionItems collection and
                          contains the members of the
                          DDL collection.
    .sub.-- NewEnum
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interface
                          of an object that implements
                          the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
                Return Type  Description
    ______________________________________
    Name (R)    VT.sub.-- BSTR
                             The parameter's name.
    Value (R) (.dagger.)
                VT.sub.-- VARIANT
                             The parameter's value.
    ValueAsString
                VT.sub.-- BSTR
                             The parameter's value as a
    (R) (.dagger.)           string.
    Size (R)    VT.sub.-- I4 The parameter's size (in
                             bytes).
    Type (R)    VT.sub.-- I4 The parameter's type.
    TypeAsString (R)
                VT.sub.-- BSTR
                             The parameter's type as a
                             string.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (C) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (C)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          stressed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          items in the collection.
                          The DatabaseParameter object
                          whose Name property matches
                          the argument is returned.
    .sub.-- NewEnum
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interface
                          of an object that implements
                          the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (N) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (N)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          accessed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          items in the collection.
                          The Device object whose
                          DeviceID property matches the
                          argument is returned.
    .sub.-- NewEnum (N)
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interface
                          of an object that implements
                          the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
               Return Type Description
    ______________________________________
    Count (C)  VT.sub.-- I4
                           The number of items in the
                           collection. This property
                           blocks until all the items in
                           the collection can be accessed
                           without blocking.
    ReadyCount (C)
               VT.sub.-- I4
                           The number of items in the
                           collection that can be
                           accessed without blocking,
                           which may be less than the
                           total number of items in the
                           collection.
    ServerCount (N)
               VT.sub.-- I4
                           Same as the Count property
                           except it does not block if
                           all the items are not
                           immediately available.
    PhysicalTag (R) (.dagger.)
               VT.sub.-- BSTR
                           The device's internal tag.
                           Note:
                           For a HART device, this is the
                           HART tag.
    DeviceTag (R)
               VT.sub.-- BSTR
                           The device's external tag.
    DeviceID (R) (.dagger. .dagger.)
               VT.sub.-- BSTR
                           The device's unique
                           identifier.
    StationAddress
               VT.sub.-- I4
                           The device's station address.
    (R) (.dagger.)
    NetAddress (R)
               VT.sub.-- BSTR
                           The device's network address
                           as a moniker.
    ______________________________________
    Method Name
               Return Type Description
    ______________________________________
    Item       VT.sub.-- DISPATCH
                           Takes one argument of type
                           VT.sub.-- BSTR and returns one of
                           the collections provided by the
                           object.
                           Collections:
                           The " Tag"  collection is a Tag
                           collection and contains all
                           the device's blocks.
                           Special Case:
                           If the argument is " HART," the
                           IDispatch interface of the
                           device's Block object is
                           returned.
    .sub.-- NewEnum
               VT.sub.-- UNKNOWN
                           Returns the IUnknown interface
                           of an object that implements
                           the IEnumVariant interface.
    ______________________________________

    ______________________________________
    Property Name
              Return Type Description
    ______________________________________
    Count (N) VT.sub.-- I4
                          The number of items in the
                          collection. This property
                          blocks until all the items in
                          the collection can be accessed
                          without blocking.
    ReadyCount (N)
              VT.sub.-- I4
                          The number of items in the
                          collection that can be
                          accessed without blocking,
                          which may be less than the
                          total number of items in the
                          collection.
    ServerCount (N)
              VT.sub.-- I4
                          Same as the Count property
                          except it does not block if
                          all the items are not
                          immediately available.
    ______________________________________
    Method Name
              Return Type Description
    ______________________________________
    Item      VT.sub.-- DISPATCH
                          Takes one argument of type
                          VT.sub.-- BSTR and returns one of the
                          items in the collection.
                          The Device object whose
                          DeviceTag property matches the
                          argument is returned.
    .sub.-- NewEnum (N)
              VT.sub.-- UNKNOWN
                          Returns the IUnknown interfa