Patent Publication Number: US-8538559-B2

Title: Fieldbus system function block enhancements using transducer block

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
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     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
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     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The process control industry utilizes standard digital communications protocols. An example is the FOUNDATION Fieldbus protocol. This protocol allows sensors, actuators, indicators, control systems, configuration systems, asset managing systems, handheld tools, and more to communicate with each other and interoperate with each other, even to the point of allowing control algorithms to reside in field devices produced by differing manufacturers, if they conform to the communications and distributed control and process monitoring standards. This digital standard allows access not only to the process values being measured or control values to be set, but also allows access to configuration parameters to tune and select options within the control and measurement algorithms, allows access to performance data, allows access to diagnostic information, and more. This standard may be applied in various process industries such as refining, power generation, chemical processing, water and wastewater treatment, pharmaceutical, etc. Stevenson et al. (U.S. Pat. No. 6,738,388) shows an example of such a system. 
     The process control industry commonly controls a process using function blocks. Function blocks are tagged software elements that periodically or on-demand gather inputs, execute an algorithm, and produce outputs. They have logic and variables called parameters. Historically, function blocks had not been standardized within the process control industry. 
     Primarily for reasons of interoperability, the communications protocol standard defines a set of standard function blocks. However, it allows manufacturers to create extensions to standard function blocks, creating enhanced function blocks. These extensions generally require additional parameters to be used as inputs, outputs, and/or algorithm controls. A limitation for field device designers has been that not all configuration systems and control systems implement the complete FOUNDATION Fieldbus standard, in particular, the portion of the standard that provides for manufacturer-specific extensions to the standard function blocks. The standard allows field device manufacturers to add parameters and connections, called manufacturer extensions or manufacturer-specific parameters. Since some configuration systems and control systems do not support these extensions, the applicable market size is reduced for field devices that utilize extended features. This lack of support restrains creativity, inhibits improvements, and limits competition. 
     Historically, the state of the art for the field device designer was to choose one of two paths. The first path was to include the manufacturer-specific parameters and manufacturer-specific connections in one or more device enhanced function blocks and accept a smaller market of application for the device since a significant portion of the installed configuration systems and control systems did not support such manufacturer-specific extensions to standard function blocks. This was to the field device manufacturer&#39;s disadvantage as it limited the field of application. 
     The second path was to exclude the potential manufacturer-specific parameters and manufacturer-specific connections in function blocks in order to accommodate a larger market of application. However, the field device designer was then precluded from providing the customer with extended, inventive, creative, and useful features beyond the minimum required by the standard. This was also to the field device manufacturer&#39;s disadvantage and it limited additional value to the device. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of an example of a process control network having a configuration system, control system, asset managing system, and distributed field devices. 
         FIG. 2  is a schematic block diagram of typical field device with function blocks. 
         FIG. 3  is a schematic block diagram showing an example of communicative connections between a control system and function blocks within field devices. 
         FIG. 4  is a timing diagram showing an example of a function block execution and network publication schedule. 
         FIG. 5  is a schematic block diagram of typical field device with function blocks as implemented using the invention. 
         FIG. 6  is a flow chart illustrating configuration downloads for communications configuration, publication and function block execution schedule, and function block parameters. 
         FIG. 7  is a flow chart illustrating the processing of an analog input function block with a manufacturer-specific enhancement which can communicate to a discrete output function block without using function block-contained manufacturer-specific output parameters. 
         FIG. 8  is a flow chart illustrating the processing of a discrete output function block with a manufacturer-specific enhancement which can receive communication from an analog input function block without using function block-contained manufacturer-specific input parameters. 
         FIG. 9  is a schematic diagram of a process control system illustrating the working of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An enhanced function block is a function block that contains all the features, functions, parameters, and controls of a standard function block plus one or more manufacturer-specific parameters which may be used to provide one or more additional functional features associated with that function block. The system described herein provides for a plurality of functional extensions to standard function blocks, beyond the standard functions defined as part of the standard function blocks. However, since some configuration and control systems do not support manufacturer-specific parameters in function blocks, this invention uses an alternate method. 
     It utilizes one or more shared transducer blocks to be used as a communicative coupling mechanism between a plurality of standard function blocks (with only standard parameters) within a device in order to permit functional extensions similar in capabilities to those that would be accomplished using manufacturer-specific function block parameters, input connections, and output connections within a standard function block base, rendering the functionality of an enhanced function block but without adding non-standard parameters to the standard function blocks. The manufacturer-specific parameters which are utilized by the function blocks are actually associated with the shared transducer block, instead of in the function blocks and are communicatively coupled between the function blocks and the transducer block. This is useful because asset-managing systems generally do provide access to manufacturer-specific parameters in transducer blocks, even though control systems and asset managing systems may not provide such access to manufacturer-specific parameters in function blocks. Each standard function block communicates with the manufacturer-specific parameters located within the associated transducer block. A function block can locate its associated transducer block by using an internal communication mechanism which is not part of the communications standard except for the use of a parameter called CHANNEL which contains manufacturer-specific information regarding the association between function blocks and associated transducer blocks. The name of the CHANNEL parameter is standardized, as is its data type and size, but the meaning of its values are defined by the device manufacturer. 
     Another aspect of this invention provides for function blocks needing to communicate with each other that cannot do so using standard output parameters connected to standard input parameters. Such function blocks may communicate with each other by storing and reading values in one or more shared transducer blocks which they access within the field device using shared parameters. 
     Hence, both the creation of manufacturer-specific parameters and the ability to communicate beyond the standard interconnections is made possible by this invention, even though a configuration system and control system may not support such extensions to standard function blocks. The manufacturer-specific parameters are located in the shared transducer block. Manufacturer-specific transducer block parameters are generally supported by asset managing systems. 
     DEFINITIONS 
     
       
         
           
               
               
             
               
                   
                   
               
               
                   
                 Definitions 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Asset 
                 As used herein, a generic computer-based system 
               
               
                 managing 
                 that collects and monitors performance and 
               
               
                 system: 
                 diagnostic data from process-related field devices 
               
               
                   
                 (typically measurement sensors and process 
               
               
                   
                 actuators such as valves and motor speed 
               
               
                   
                 controllers) in order to provide plant maintenance 
               
               
                   
                 personnel and management personnel with 
               
               
                   
                 information and alerts regarding existing or 
               
               
                   
                 potential failures of process-related equipment. 
               
               
                 Control 
                 A system whose function is to automatically 
               
               
                 System: 
                 control or assist in the control of a process such 
               
               
                   
                 as refining, producing chemicals, producing 
               
               
                   
                 electric power, purifying water, processing 
               
               
                   
                 wastewater, manufacturing cement, etc. 
               
               
                 Discrete 
                 An input whose values are discrete such as ON or 
               
               
                 Input: 
                 OFF, TRUE or FALSE; OFF, STARTING, RUNNING, 
               
               
                   
                 or STOPPING, etc. 
               
               
                 Discrete 
                 An output whose values are discrete such as ON 
               
               
                 Output: 
                 or OFF, TRUE or FALSE; START or STOP, etc. 
               
               
                 Distributed 
                 A control system whose functional elements are 
               
               
                 Control 
                 physically and logically distributed and 
               
               
                 System 
                 interconnected via a communication system, 
               
               
                 (DCS): 
                 typically a network. 
               
               
                 Enhanced 
                 A standard function block which meets the 
               
               
                 Function 
                 requirements of the standard function block but 
               
               
                 Block: 
                 contains additional features or enhancements 
               
               
                   
                 made accessible by one or more manufacturer- 
               
               
                   
                 specific parameters which may include additional 
               
               
                   
                 input and/or additional output parameters used as 
               
               
                   
                 connections. 
               
               
                 Fieldbus: 
                 An industrial computer network protocol used for 
               
               
                   
                 real-time distributed control. 
               
               
                 FOUNDA- 
                 A digital communication and process control 
               
               
                 TION 
                 standard specific to and promoted by the Fieldbus 
               
               
                 Fieldbus: 
                 Foundation. 
               
               
                 Function 
                 A named structure containing parameters that 
               
               
                 Block: 
                 control the execution of an associated algorithm 
               
               
                   
                 which, in general, periodically acts on inputs and 
               
               
                   
                 produces outputs. 
               
               
                 Manufacturer- 
                 A parameter which is not standardized by an 
               
               
                 Specific 
                 entity having such authority, but rather defined by 
               
               
                 Parameter: 
                 a manufacturer entitled to do so. 
               
               
                 Parameter: 
                 Block parameters define the inputs, outputs, and 
               
               
                   
                 the data used to control block operation. They 
               
               
                   
                 are generally visible and accessible over the 
               
               
                   
                 network. 
               
               
                 Shared 
                 A transducer block that is associated with more 
               
               
                 Transducer 
                 than one function block for the purpose of 
               
               
                 Block: 
                 allowing two or more function blocks to 
               
               
                   
                 communicate to each other and/or provide 
               
               
                   
                 parameter storage for one or more associated 
               
               
                   
                 function blocks. 
               
               
                 Standard 
                 A parameter standardized by an entity having 
               
               
                 Parameter: 
                 such authority. 
               
               
                 Standard 
                 A function block standardized by the entity having 
               
               
                 Function 
                 such authority, for example, the Fieldbus 
               
               
                 Block: 
                 Foundation. A standard function block performs 
               
               
                   
                 all the functions required by the standard. 
               
               
                 Transducer 
                 A named structure containing parameters that 
               
               
                 Block: 
                 control the execution of an associated algorithm 
               
               
                   
                 which, in general, periodically or on demand acts 
               
               
                   
                 on process measurement inputs and/or produces 
               
               
                   
                 process control or actuator outputs 
               
               
                   
               
               
                 Abbreviations 
               
               
                 DCS: Distributed Control System 
               
               
                 HMI: Human Machine Interface—a mechanism for a human to view and possibly alter values associated with a computer program and its memories. 
               
            
           
         
       
     
     The Fieldbus communication system interconnects control systems, configuration systems, asset managing systems, field devices (e.g. sensors and actuators), and the like.  FIG. 1  shows an example of a typical arrangement. In this example, there is the following: 
     A configuration system  1 , also sometimes called a configuration tool, composed of one or more configuration processors and memories  2  containing one or more configuration programs  3  and one or more human-machine interfaces (HMIs)  4  which may also be remote to the configuration system. The configuration system provides configuration services for the various devices and network connections involved with communications. Configuration may be performed on-line, communicating to connected devices. Configuration may also be performed off-line, in a database, with the resultant values downloaded to the other devices at a later time. Configuration includes establishing network parameters, establishing device system parameters, establishing parameters for resource blocks, function blocks, and transducer blocks, interconnecting function blocks internally within a device and externally between devices, establishing a publication schedule for the communications link, and so forth. 
     A control system  5 , also sometimes called a distributed control system (DCS), composed of one or more control processors and memories  6  containing one or more control programs  7  and one or more human-machine interfaces (HMIs)  8  which may also be remote to the control system. A control system gathers process measurement values from field sensor devices in order to monitor and control the process. Control algorithms allow the control system to compute needed changes to the process, per operator-provided setpoints. The control system can then alter the process via communications to field actuator devices such as control valves and motor speed controls. The control system also can provide alerting about deviant measured process values, useful displays for the benefit of the operators, reports of performance for plant management, and the like. 
     An asset managing system  9 , also sometimes called a field device management system, composed of one or more asset managing processors and memories  10  containing one or more asset managing programs  11  and one or more human-machine interfaces (HMIs)  12  which may also be remote to the asset managing system. The asset managing system generally monitors the field device performance and diagnostic parameters, alerting its users and operators to existing, imminent, pending, scheduled, or potential needs for maintenance services. It typically would produce a prioritized list of field equipment (sensors, actuators, and the like) that have failed, are not functioning well, are showing signs of impending failure, are scheduled for maintenance based on calendar time or operating time, and the like. 
     It is also possible for any two or more systems of the above configuration, control, and asset managing systems to be combined into one. For example, a distributed control system may contain a configuration system within itself or may contain an asset managing system within itself. 
     One or more networks  13  (or fieldbus communications systems) may be used to interconnect the above systems and one or more field devices  14 . The networks may be of differing communications speeds using specialized devices to interface lower speed and higher speed sub-networks together. 
     A Field Device (e.g.,  14 ) of  FIG. 1  is further detailed in the example of  FIG. 2 . In this example of field devices prior to this invention, Field Device  17  contains processor and memory  18 , field device programs  19 , and four function blocks and three transducer blocks. An analog input function block  20  is associated with an analog input transducer block  21  by way of an internal connection  22 . The standard analog input transducer block scans an input value from an associated sensor based on its configured parameters. The standard analog input function block communicates an input measurement value provided by the analog input transducer block and converts it to desired engineering units, can filter the value to reduce the effect of noise, compares the value to alarm limits, and can generate an alarm alert when limits are exceeded. It also provides for manual value substitution if needed and for other features. The analog input transducer block provides the logic and needed parameter values to properly process the desired measurement value through the hardware interface. 
     Two discrete input function blocks  23  and  24  share a discrete input transducer block  25 , but not for the purpose of communications between the associated function blocks  23  and  24  or for the purpose of containing one or more manufacturer-specific parameters that would provide functionality expected in the associated function blocks  23  and  24 . The internal connection  26  provides only an association between discrete input function block  23  and discrete input transducer block  25 , but not between discrete input function block  23  and discrete input function block  24 . The internal connection  27  provides only an association between discrete input function block  24  and discrete input transducer block  25 , but not between discrete input function block  23  and discrete input function block  24 . The standard discrete input transducer block scans an input status value from an associated discrete sensor based on its configured parameters. The standard discrete input function block obtains an input value from the discrete input transducer block and may invert its value, can filter the value to reduce the effect of noise, compares the value to an alarm limit, and can generate an alarm alert when the limit is exceeded. It also provides for manual value substitution if needed and for other features. The discrete input transducer block provides the logic and needed parameter values to properly process the desired status value through the hardware interface. 
     Lastly, a discrete output function block  28  is associated with a discrete output transducer block  29  by way of an internal connection  30 . The discrete output function block accepts a target value from the operator or via another function block, may invert it, and provides it to the discrete output transducer block. It also provides for manual value substitution if needed and for other features. The discrete output transducer block provides the logic and needed parameter values to properly process the desired discrete value through the hardware interface. 
     An example of communicative coupling via the network is shown in the schematic diagram of  FIG. 3 . The control system  31 , also called distributed control system, contains communicative couplings via a network to the function blocks that reside in the field devices. DCS analog input  32  is communicatively coupled via connection  37  through network  42  to analog input function block  44  in field device  43 . DCS discrete input # 1   33  is communicatively coupled via connection  38  through network  42  to discrete input # 1  function block  46  in field device  45 . DCS discrete input # 2   34  is communicatively coupled via connection  39  through network  42  to discrete input # 2  function block  48  in field device  47 . DCS discrete output  35  is communicatively coupled via connection  40  through network  42  to discrete output function block  50  in field device  49 . DCS analog output  36  is communicatively coupled via connection  41  through network  42  to analog output function block  52  in field device  51 . 
     The communicative coupling between the function blocks typically uses a communication mechanism called publication-subscription, wherein the device containing the producing function block publishes a value to the network and the device containing the consuming function block subscribes to the published value. In order to facilitate the communicative coupling between the function blocks, a publication schedule, sometimes called a link schedule, is produced by the configuration system. 
       FIG. 4  is an example of a publication schedule shown as a timing chart that could be used to provide the communicative coupling needed in  FIG. 3 . The timing chart contains indications of both when to execute a function block and when to publish its outputs, all expressed relative to the start of a periodically repetitive schedule called the macrocycle. The duration of the macrocycle determines the periodicity of execution and of publication, although a block may execute or publish more than one time during a macrocycle. 
     No more than one device may publish a function block output to the network at the same time. In a single processor device, no more than one function block may execute at the same time. The schedule is intended to publish a value close to the time it is produced so that it is available and fresh. 
     In  FIG. 4 , the macrocycle schedule indicates that the control system (DCS) is scheduled  60  to publish a discrete output to the network. Next, the analog input function block in a field device is scheduled  61  to execute. When publication  60  has completed, the control system (DCS) is scheduled to publish  62  an analog output to the network. When the execution of the analog input function block  61  has completed, the device is scheduled  63  to execute discrete input # 1  function block. When publication  62  has completed, the field device is scheduled to publish  64  an analog input to the network. When the execution of the discrete input # 1  function block  63  has completed, the device is scheduled  65  to execute discrete input # 2  function block. When publication  64  has completed, the field device is scheduled to publish  66  a discrete input # 1  to the network. When the execution of the discrete input # 2  function block  65  has completed, the device is scheduled  67  to execute a discrete output function block. When publication  66  has completed, the field device is scheduled to publish  68  a discrete input # 2  to the network. When the execution of the discrete output function block  67  has completed, the device is scheduled  69  to execute an analog output function block. After publication  68  has completed, the field device is scheduled to publish  70  a back-calculation value from the discrete output function block to the network. When the execution of the analog output function block  69  has completed, no more executions of function blocks are scheduled until the macrocycle repeats itself after the macrocycle duration has expired. When publication  70  has completed, the field device is scheduled to publish  71  a back-calculation value from the analog output function block to the network. When publication  71  has completed, no further publications are scheduled until the macrocycle repeats itself after the macrocycle duration has expired. This macrocycle schedule, also called a link schedule or link active schedule, is downloaded to devices that require it. Synchronization of publications and function block execution timing is maintained by devices sharing a common knowledge of time. 
       FIG. 5  shows the use of this invention within the field device  84 . In this example, an analog input function block  72 , discrete input function block  73 , second discrete input function block  74 , and discrete output function block  75  all share a shared input and output transducer block  76  each through its own internal connection  77 ,  78 ,  79 , and  80 , respectively. A function block can locate its associated transducer block by using an internal connection mechanism which is not part of the communications standard except for the use of a parameter called CHANNEL which contains manufacturer-specific information regarding the association between function blocks and associated transducer blocks. The CHANNEL parameter is standard in name, data type, and size, but the interpretation of its value is open to each manufacturer&#39;s own specific definition. 
     In this example, the shared transducer block is utilized for (in addition to interfacing and accessing the process measurement input hardware and process actuation output hardware) [1] communications among the analog input function block  72 , discrete input function block  73 , second discrete input function block  74 , and discrete output function block  75  and [2] storage of one or more manufacturer-specific parameters for benefit of any of the associated function blocks. For example, if the state of the physical discrete output associated with the discrete output function block  75  should be OFF whenever the value of the physical analog input associated with the analog input function block  72  is in an active alarm condition because it is above a high limit, such an option for the discrete output function block  75  is indicated via a manufacturer-specific parameter stored in the shared input and output transducer block  76  and the state resulting from the analog input function block&#39;s  72  high alarm condition will be stored in the shared input and output transducer block  76  for the discrete output function block  75  to observe. In other words, the analog input function block  72  communicates its alarm state to the discrete output function block  75  via shared storage in the shared input and output transducer block  76 . In this example, both the analog input function block  72  and discrete output function block  75  have specialized logic, in addition to the standard logic, to facilitate this communications through the shared input and output transducer block. 
     Also in this example, analog output function block  81  is associated with an analog output transducer block  82  by way of an internal connection  83 , independent of the shared input and output transducer block  76 . 
       FIG. 6  illustrates an example of a flow chart for software which downloads a configuration database. The user, using the configuration system, prepares a configuration database describing the communicating devices of the network, the interconnections between function blocks throughout the network, and the timing of the execution of the function blocks. The timing of publications of values to the network is usually derived by the configuration software program. A block  100  receives the configuration of the communicating devices from the configuration database for block  101  to download appropriate portions to each device participating in the communications. A block  102  receives the configured schedule from the configuration database for block  103  to download appropriate portions to each device participating in the scheduled communications and execution of scheduled function blocks. A block  104  receives the configuration of the block parameter values (for resource blocks, function blocks, transducer blocks) from the configuration database for block  105  to download appropriate downloadable parameter values to each block within devices participating in the communications. 
       FIG. 7  illustrates an example of a flow chart for the analog input function block  72  of  FIG. 5 . In  FIG. 5  the analog input function block  72  has only the standard function block parameter set. The shared input and output transducer block  76  contains two non-standardized manufacturer-specific parameters FORCE_OFF_OPTION and FORCE_OFF_ACTIVE in this example. Each standard function block can communicate with the manufacturer-specific parameters located within the associated transducer block. 
     The FORCE_OFF_OPTION parameter is an enumerated parameter that can take on one of three user-determined discrete values of “Never”, “High Alarm”, or “Low Alarm”. The user selects a value at the time of configuration. The default value is “Never”. If the value of “Low Alarm” is selected, the occurrence of a low alarm condition in the analog input function block will cause the discrete output function block to force itself to an OFF state. If the value of “High Alarm” is selected, the occurrence of a high alarm condition in the analog input function block will cause the discrete output function block to force itself to an OFF state. If the value of “Never” is selected or there by default, then neither the occurrence of a high alarm condition nor the occurrence of a low alarm condition in the analog input function block will cause the discrete output function block to force itself to an OFF state. 
     The FORCE_OFF_ACTIVE parameter is an enumerated parameter that can take on one of two function block-determined discrete values of “Yes” or “No”. If the value of “High Alarm” is selected in the FORCE_OFF_OPTION parameter, the analog input function block will access the FORCE_OFF_ACTIVE parameter in the shared input and output transducer block and will set its value to “Yes” if there is an active occurrence of a high alarm condition in the analog input function block or will set its value to “No” if there is no active occurrence of a high alarm condition in the analog input function block. If the value of “Low Alarm” is selected in the FORCE_OFF_OPTION parameter, the analog input function block will access the FORCE_OFF_ACTIVE parameter in the shared input and output transducer block and will set its value to “Yes” if there is an active occurrence of a low alarm condition in the analog input function block or will set its value to “No” if there is no active occurrence of a low alarm condition in the analog input function block. If the value of “Never” is selected in the FORCE_OFF_OPTION parameter, the analog input function block will access the FORCE_OFF_ACTIVE parameter in the shared input and output transducer block and will set its value to “No”. 
     The example flow chart in  FIG. 7  shows that the standard portion of the analog input function block is executed in block  110 . After completion of the alarm determination portion of the standard function block logic, a test is made to determine if the FORCE_OFF_OPTION parameter is set to “High Alarm” and if a high alarm condition is active in  111 . If not, a similar test is made to determine if the FORCE_OFF_OPTION parameter is set to “Low Alarm” and if a low alarm condition is active in  112 . If neither of these conditions is true, box  113  will set the FORCE_OFF_ACTIVE parameter in the shared input and output transducer block  76  to “No”. If either of these conditions is true, box  114  will set the FORCE_OFF_ACTIVE parameter in the shared input and output transducer block  76  to “Yes”. 
       FIG. 8  illustrates a flow chart for the discrete output function block of  FIG. 5 . In  FIG. 5  the discrete output function block  75  has only the standard function block parameter set. The shared input and output transducer block  76  contains two non-standardized manufacturer-specific parameters FORCE_OFF_OPTION and FORCE_OFF_ACTIVE. 
     The flow chart in  FIG. 8  shows that a standard portion of the discrete output function block is executed in block  120 . In block  121 , a test is made of the manufacturer-specific parameter FORCE_OFF_ACTIVE. If the value of FORCE_OFF_ACTIVE is “Yes”, the discrete output value will be forced to OFF in block  122  regardless whether it was to be ON or OFF before this point. If the value of FORCE_OFF_ACTIVE is not “Yes”, the discrete output value will be unaltered. Block  123  will output the discrete output value to the hardware. 
     In summary, the analog input function block  72  can communicate its alarm condition to the discrete output function block  75  without the analog input function block  72  having its own manufacturer-specific output parameter to provide it, and without the discrete output function block  75  having its own manufacturer-specific input parameter to accept it. This is accomplished by the analog input function block  72  communicating its alarm condition through (writing its alarm condition to) the manufacturer-specific parameter FORCE_OFF_ACTIVE located in the shared input and output transducer block followed by the discrete output function block  75  reading the same said condition by way of the same said manufacturer-specific parameter FORCE_OFF_ACTIVE located in the same said shared input and output transducer block. This provides a manufacturer-specific communications connection that is supported by systems that support manufacturer-specific parameters in transducer blocks, even though they may not support manufacturer-specific parameters in function blocks. 
     Further, configuration parameters such as FORCE_OFF_OPTION are manufacturer-specific but reside, per this invention, in the shared input and output transducer block rather than directly in the function block. This provides manufacturer-specific configuration options that are supported by systems that support manufacturer-specific parameters in transducer blocks, even though they may not support manufacturer-specific parameters in function blocks. 
     Reference is made to  FIG. 9 , which illustrates the structure of an embodiment of the system. A fieldbus network as illustrated in  FIG. 1  contains at least one field device  204 . The field device  204  includes at least two function blocks  206  and  208  and a shared transducer block  212 . All of the device description files  210  include both standard and non-standard parameters (which exist in software in the field device  204 ). These description files are accessed and read by the distributed control system  200  and the asset management system  202 . However, the distributed control system  200  accesses only standard parameters from the function blocks  206  and  208  as indicated by dotted line  215 . It cannot access the non-standard parameters. The asset management system  202  is an alternate system for collecting and monitoring data from the field device  204 . The alternate system  202  does access the non-standard parameters that are in the shared transducer block  212  as indicated by dotted line  213 . For this reason, non-standard parameters that would otherwise be located in function blocks are located instead in an associated transducer block, and links (denoted by the arrows  217  and  219 ) are formed between the function blocks  206  and  208  to access these parameters and to communicate to each other using these non-standard parameters. 
     The terms and expressions that have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.