基金会现场总线应用指南——functionblockhybridbatchhse

F OUNDATION? fieldbus Application Guide Function Block Capabilities in Hybrid/Batch Applications

NOTICE

This document was developed by a Fieldbus Foundation study team to illustrate possible use of F OUNDATION?fieldbus function block technology in hybrid/batch applications and is not a normative technical specification. The information presented in this document is for the general education of the reader. The reader is expected to exercise sound professional judgment in using any of the information presented in a particular application.

The Fieldbus Foundation has not investigated or considered the affect of any patents on the ability of the reader to use any of the information in a particular application. The reader is responsible for reviewing any possible patents that may affect any particular use of the information presented.

Any references to commercial products in this document are examples only and the Fieldbus Foundation does not endorse any referenced commercial product. Any trademarks or trade names referenced belong to the respective owner of the mark or name. The Fieldbus Foundation makes no representation regarding the availability of any referenced commercial product at any time. The manufacturer’s instructions on use of any commercial product or display of any trademark or trade name must be followed at all times, even if in conflict with the information in this document.

This document is provided on an “as is” basis and may be subject to future additions, modifications, or corrections without notice.

DISCLAIMER OF WARRANTIES

THE FIELDBUS FOUNDATION HEREBY DISCLAIMS ALL WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, FOR THIS DOCUMENT. IN NO EVENT WILL THE FIELDBUS FOUNDATION BE RESPONSIBLE FOR ANY LOSS OR DAMAGE ARISING OUT OF OR RESULTING FROM ANY DEFECT, ERROR OR OMISSION IN THIS DOCUMENT OR FROM ANYONE’S USE OF OR RELIANCE ON THE INFORMATION IN THIS DOCUMENT.

DOCUMENT: AG-170 (Formerly FF-950)

REVISION: 1.1

ISSUE DATE: 4 December 2002

Copyright by the Fieldbus Foundation 1994-2002. All rights reserved.

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Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0

Table of Contents

1.Purpose (1)

1.1Scope (1)

1.2FF References (1)

1.3Definitions (1)

1.4Acronyms and Abbreviations (1)

1.5Synopsis of Specifications (2)

1.5.1FF-893 Multiple I/O Blocks (2)

1.5.2FF-804 Multi-Variable Optimization (2)

1.5.3FF-892 FBAP Part 3 (2)

1.6Drawing Conventions (3)

1.6.1Process Diagram (3)

1.6.2Field Wiring (3)

1.6.3Function Block Diagram (3)

2.Application Overview (4)

2.1Parameters (4)

2.2Block Execution (4)

2.3Views (4)

2.4Function Block Notes (4)

2.4.1Supported Modes (5)

2.4.2Alarm Types (5)

2.4.3Mode Handling (5)

2.4.4Status Handling (5)

2.4.5Initialization (5)

2.4.6Power Failure Recovery (5)

3.Flexible Function Block Applications (6)

3.1Snap Control (6)

3.1.1Overview (6)

3.1.2Process Diagram (6)

3.1.3Field Wiring (6)

3.1.4Function Block Diagram (7)

3.1.5Block Access (7)

3.2Multivariable Matrix Control (9)

3.2.1Overview (9)

3.2.2Process Diagram (9)

3.2.3Field Wiring (9)

3.2.4Function Block Diagrams (10)

3.2.5Block Access for FFB1 (12)

3.2.6Block Access for FFB2 (13)

3.3Variable Speed Drive Control (14)

3.3.1Overview (14)

3.3.2Process Diagram (14)

3.3.3Field Wiring (14)

3.3.4Function Block Diagram (14)

3.3.5Block Access for FFB1 (16)

3.3.6Additional thoughts on Fieldbus Drives (17)

3.4Four Discrete Valve Control (25)

3.4.1Overview (25)

3.4.2Process Diagram (25)

3.4.3Field Wiring (25)

3.4.4Function Block Diagram (26)

3.4.5MVC Object List (27)

3.5Extended PID with Autotuner (28)

3.5.1Overview (28)

3.5.2Process Diagram (28)

3.5.3Field Wiring (28)

3.5.4Function Block Diagram (28)

3.5.5Block Access for FFB1 (29)

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3.5.6MVC Lists (29)

3.6Fermentation Zymolysis Control (30)

3.6.1Overview (30)

3.6.2Process Diagram (30)

3.6.3Description (30)

3.6.4Block Access (31)

3.7Distillation Startup and Shutdown (31)

3.7.1Overview (31)

3.7.2Description of the Hybrid Step (31)

3.7.3Sequential Control (34)

3.7.4Distillation Initialization Check Logic (37)

3.7.5List of Variables (38)

3.8Integration path for a legacy system and multiple field HART interface (38)

3.8.1Overview (38)

3.8.2Process diagram (39)

3.8.3Field Wiring (40)

3.8.4Function Block Diagram (40)

3.8.5Block Access (41)

3.9PROCESS COOLING WATER SYSTEM (41)

3.9.1Scenario (41)

3.9.2Receiver Level Control (41)

3.9.3Distribution Pump Control (41)

3.9.4Process Cooling Water Temperature Control (42)

3.9.5Variable Frequency Drives Monitoring (42)

4.Detailed Plant Applications (44)

4.1Multivariable Matrix Control Application (44)

4.1.1Overview (44)

4.1.2Process Diagram (45)

4.1.3Matrix Diagram (46)

4.1.4System Architecture (46)

4.1.5Field Wiring (47)

4.1.6FFB-MVMC Parameters (48)

4.1.7Conclusions (49)

4.2Application Profile - Cleanroom Makeup Air Unit (50)

4.2.1Scenario (50)

4.2.2System Description (50)

4.2.3System Integration (50)

4.2.4Control Strategy/Sequence of Operations (50)

4.3Packaged Batch Distillation Control (55)

4.3.1Overview (55)

4.3.2Process Diagram (55)

4.3.3Field Wiring (56)

4.3.4Function Block Diagrams (57)

4.4Variable Frequency Drives (VFD) and FFB Integration Example (60)

4.4.1Overview (60)

4.4.2Process Description (60)

4.4.3VFD & FOUNDATION? fieldbus (62)

4.4.4Characteristics Table (65)

4.4.5Modes of operation (65)

4.4.6Parameter Lists (65)

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Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0

1. Purpose

This document describes possible applications in order to facilitate understanding of the uses for the Flexible Function Block and the various methods required to create them.

1.1 Scope

The applications describe analog, discrete and hybrid applications for Flexible Function Blocks. The specification consists of examples for the use of normative statements made in the FF-89x Function Block Application Process specifications. This specification is informative.

1.2 FF References

Number Revision Date Title

FF-804 FS 1.0 August 15, 2000 Multi-Variable Optimization Addendum

FF-890 FS 1.5 November 5, 2001 Function Block Application Process Part 1 (Architecture)

FF-891 FS 1.5 October 28, 2001 Function Block Application Process Part 2 (10 Standard Blocks)

FF-892 FS 1.5 November 5, 2001 Function Block Application Process Part 3 (Additional Blocks)

FF-893 FS 1.0 March 14, 2000 Function Block Application Process Part 4 (Multiple I/O)

FF-894 FS 1.0 September 21, 2001 Function Block Application Process Part 5 (Flexible Block)

1.3 Definitions

All definitions are in the Function Block Application Process specifications listed above in FF References, except:

Profile: A concise descriptive sketch of a much more detailed application. (Webster - 5: A concise biographical sketch.)

1.4 Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

DC: Device Control function block.

DD: Device description.

FFB: Flexible Function Block.

FOD: Fixed Object Dictionary.

FPR: Fixed Object Dictionary for a Programmable Resource.

VOD: Variable Object Dictionary.

VPR: Variable Object Dictionary for a Programmable Resource.

VRB: Resource Block for a Programmable Resource.

MIO: Multivariable Input/Output.

MVC: Multivariable Container.

OD: Object Dictionary for one VFD.

URL: Uniform Resource Locator. Internet RFC 1738 defines the syntax and semantics.

VFD: Virtual Field Device.

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1.5 Synopsis of Specifications

The following specifications contain material that is essential to understand before the application profiles can be understood. An overview of that material is given for the general reader. Knowledge of FF-890 and FF-891 is presumed, as they are central to the function blocks available from all H1 device vendors.

1.5.1 FF-893 Multiple I/O Blocks

The standard I/O blocks defined in FF-891 have exactly one physical element for each block. FF-893 introduces I/O blocks that have multiple physical elements. For example, the Multiple Discrete Input block has 8 discrete outputs. The primary purpose for these blocks is to serve as an interface between FF and the remote I/O units used by PLC systems. MIO blocks solve the problem of assigning channel numbers to inpidual bits or analog values in remote I/O units. The MIO CHANNEL parameter refers to an entire remote I/O unit.

The MIO blocks are specific subclasses of the Flexible Function Block class. Similar blocks may be built with any number of I/O variables.

1.5.2 FF-804 Multi-Variable Optimization

The limited information bandwidth of H1 may make it necessary to consolidate some of the variables in a device for transmission in a single message. For example, the eight discrete outputs of an MDI block may be published in a single message instead of eight separate messages. This makes the values available to any other device on the H1 bus that wishes to subscribe to the single message published by the device that contains the MDI block. The subscribing device has a list that matches the list of variables published, except that it directs the values to inputs of blocks within the subscribing device. Inpidual published values may be ignored if the subscribing device does not use them.

In the publishing device, output values are gathered into a Multi-Variable Container for broadcast in a message. The location of each value is determined by its OD index, so the values are not limited to one function block within the device. The size of the container is limited by the maximum message size on the H1 bus. In the subscribing device, the MVC contains the OD indexes of the function block inputs that are to receive the data. The lists are kept synchronized by a revision number.

Published MVC messages are restricted to objects of the class Output, and subscriber MVC lists may only contain objects of the class Input. This scheme is intended only for linking function block outputs in one device to function block inputs in another.

The MVC may also be used to gather function block objects of the classes Input, Output, and/or Contained to be sent as a Report Distribution message. Any Host device may subscribe to this message. It functions like a Variable List (e.g., View) object except that it does not have to be requested, it may contain values from several blocks, and it can be scheduled at any multiple of the Macrocycle. It is also true that an MVC Report Distribution message may consist of a standard function block View.

The choice of method is determined by considerations including network loading, device functionality and host support.

1.5.3 FF-892 FBAP Part 3

This specification contains many useful function blocks, but the one used in this document is the Device Controller (DC). It is intended to control any two or three state (e.g., position or speed) physical device, in the sense that it accepts a setpoint and causes the device to drive to that setpoint. Time is allowed for the transition, but alarms are generated if the physical device fails to reach the desired state or loses that state after the transition is complete. The DC block has inputs for control of the setpoint by external logic or commands from a host, as well as permissive, interlock and shutdown (emergency stop) logic functions. An operator may temporarily bypass a faulty limit switch after visual confirmation of the state of the physical device. The parameter DC_STATE displays one of 14 states that describe the current control condition (e.g., Open, Opening, Delaying, Failed to Open, Failed to leave Closed, Locked Out). The parameter FAIL gives specific reasons for failures.

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? Fieldbus Foundation 1994-2002. Page 3 1.6 Drawing Conventions

1.6.1 Process Diagram

A Process Diagram is a sketch of process piping and vessels with sensors and actuators, along with some descriptive text. No field wiring is shown because many fieldbus arrangements are possible, and wiring clutters up the drawing with detail that is not essential to the

application. The ‘tags’ have three characters: first is the process variable type that is being sensed or controlled, second is T for transmitter or C for control, and third is a loop number. An analog device tagged ‘PC1’ will have a sensor ‘PT1’ linked to it over fieldbus, unless otherwise specified in the text.

1.6.2 Field Wiring

This heading is used for descriptive text concerning the field wiring. A diagram is present when the wiring method is essential to the application.

1.6.3 Function Block Diagram

A Function Block Diagram shows the FF function blocks used in the application. Links between blocks are shown in one of three ways: Solid line - a conventional link between single output and single input.

Double line - a cascade control connection with connections in the forward and backward directions.

Dotted line - a link made using the Multi-Variable Optimization.

Links may or may not be made over fieldbus, depending on the application. Multi-Variable Optimization links are never made within the same device because communication is not involved.

Function block parameters of the class Contained are not shown in the diagram because it is only intended to show links. Function block parameters are listed under the heading ‘Block Access’ in the specifications or in this document when describing an application FFB. No attempt is made to group blocks into devices. Many arrangements are possible with F OUNDATION fieldbus.

This diagram represents two sensors within the same physical fieldbus device.

This diagram represents a fieldbus device attached to an analog actuator. It contains a

control block and an analog output block. It may also contain discrete input blocks for

position sensors.

This diagram represents a fieldbus device attached to a discrete actuator. It contains a

discrete output block, and may contain a discrete control block. It may also contain a

multi-state discrete input block for position sensors.

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.1

2. Application Overview

The applications described in this document are intended to illustrate the capabilities of the Flexible Function Block defined in FF-894, as well as the Multiple I/O blocks defined in FF-893 and the Multi-Variable Optimization defined in FF-804.

The method chosen for describing each application in Section 3 is to specify a function block in much the same manner as the standard function blocks in FF-891 and FF-892. Each specified block is an Application Specific function block and should not be confused with a standard block.

Section 4 places more emphasis on the process and less on the details of the blocks.

A Flexible Function Block may have its function defined in one of two ways:

1. A user familiar with Distributed Control Systems may choose to write a program that is compiled for the target device and

downloaded to a Domain in that device. The code does not have to be compiled. It could be written in something like BASIC and downloaded as text to a Domain in a device that interprets it.

2. A user familiar with Programmable Logic Controllers may choose to use a PLC programming tool to develop an application program

in any of the IEC 61131-3 languages that the device can execute. The program is also downloaded to a Domain, but the operation of the program is controlled by a Program Invocation object.

In either case, the device that accepts human programming input may have to be matched to the device. The connection to the device may be proprietary, using a non-F OUNDATION fieldbus Ethernet port, or it may use the standard FF means to modify the device. The programming device may also be required to modify the Object Dictionary of the device in order to create the required FFB. This depends on the complexity of the device.

1. A field device may be built with an Object Dictionary that cannot be modified by user programming. In that case, each FFB has a

predefined set of parameters much like the predefined set of registers in a PLC. The DD for the device will define the names of the parameters. The vendor needs a DD compiler but the user does not, unless the user can change parameter names.

2. A programming device may be built for the purpose of programming field devices, which can generate a new OD and DD for the

specific application. Both the programming device and field device require a higher level of complexity than those with predefined OD structures.

Once the application and the FFB are defined in the device, it is necessary to configure values for the Block object and the parameter objects. It is also necessary to link input and output parameters if other function blocks are involved. Finally it may be necessary to create the Variable List objects that are the four Views of the block. It must be possible to do these things with standard FF configuration tools because they are interoperable communication functions of the device.

The following sections are notes on general properties uncovered by the effort to specify specific blocks.

2.1 Parameters

If a parameter is defined as an Input or Output, then its data type must be one of those listed in FF-890, section 5.13. These parameters are coupled between blocks by the linking system, which can only handle the standard data types. Parameters used only for client/server communication may have structures defined by the manufacturer, or by the user but only if the device supports variable OD and DD. New parameters must be designed following the rules defined in FF-894, Parameters with Special Semantics.

2.2 Block Execution

The non-programmable resource device blocks (DCS style) are executed as specified in the Block object. The algorithm is executed as part of block execution.

The programmable resource device (PLC style) executes the program cyclically. The rate is defined by the manufacturer. The FFBs are executed as specified in the Block object. This means that the program could run any number of times between block executions, or exactly once. The block snaps the internal registers to/from the communication objects (parameters) only when it executes.

2.3 Views

View objects are defined for the FFB in this document. They may not be mandatory. A View object is a sub-class of the FMS Variable List object, which consists of a list of object indexes. FMS has services to read or write variable lists. Thus a block can be configured in a few writes by using the static View lists. The size numbers in every block access table keep track of the size of a variable list message, which is limited to about 100 octets. Hosts with the required FMS services may configure new or existing variable lists in any device that has the matching FMS services.

2.4 Function Block Notes

The Function Block Note headings are used to describe all function blocks. The contents vary with inpidual blocks. The following notes apply to all FFB specified in this document except as noted in the application text.

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2.4.1 Supported Modes

O/S and Auto. If the block has control outputs, it may support Manual. In Manual mode all of the outputs may be turned on and off regardless of the state of the input. Blocks that have internal setpoints may support Cas and/or RCas, as indicated by the required parameters being listed in the Block Access table.

2.4.2 Alarm Types

The presence of alarms is indicated by the required parameters being listed in the Block Access table.

2.4.3 Mode Handling

Standard but complicated by multiple setpoints and outputs. Since there is only one mode, it applies to all of them.

2.4.4 Status Handling

Standard, unless described in the text of an application. The rules defined in FF-890 may not be broken.

2.4.5 Initialization

Standard.

2.4.6 Power Failure Recovery

Retain and restore any internal values necessary to sustain specified operation after a power blink.

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3. Flexible Function Block Applications

3.1 Snap Control

3.1.1 Overview

This application controls the level in a sump at three discrete points using two pumps. Normally, the pumps are alternated to extend their life. When the level is excessive both pumps are turned on.

This application uses the Fixed OD FFB. This block has a predefined OD that is described in the fixed DD and the Capabilities file for the device. The algorithm used by the block is configured by typing a list of structured text like commands intro string parameters. Functions include Boolean logic as well as various timers enabling logic and sequence. Additional function blocks such as analog alarm can be instantiated to cater e.g. for a scheme where a level transmitter is used instead of switches. The device can execute logic based on its own local I/O as well as signals received over the Fieldbus. In this application all I/O are local thus allowing the device to operate autonomously even if the H1 communication fails, provided power is still available. This is an example of an application where conventional discrete on/off signals have to be interfaced to the Fieldbus environment. This application is typical, and proves the viability of the many similar mixed applications that exist during the transition to pure Fieldbus systems, such as pressure switches, push buttons, on/off valves, motor control centers, variable speed drives, and electrical actuators, motor operated and conveyors etc.

3.1.2 Process Diagram

YD1 and YD2 control the two sump pumps. ZS1 closes at the very high level, ZS2 closes at the high level and ZS3 opens when the level drops below the low level setting.

3.1.3 Field Wiring

A single field device located near the sump, to minimize the wire run, can contain this application. Low-cost wiring, carrying voltage and current supplied by the device, would connect it to the level switches and motor starters.

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Auxilliary Power

3.1.4 Function Block Diagram

The block uses three of the discrete inputs for the states of Low, High and Very High. It uses two of the discrete outputs for the two pumps. When the Low state is true, both digital outputs are turned off. When the High state becomes true, the previous output remains off and the other output turns on. When the Very High state becomes true, both outputs are turned on and an alarm may be generated.

Manual mode is supported to allow the pumps to be turned on or off at the FFB.

The block has no setpoint parameter because the level setpoints are determined by the physical placement or adjustment of the level switches. Input and output parameters are not required by a local device. They are shown so that they may be read over the bus. Conventional discrete I/O thus become available in regular Fieldbus blocks and integrate into the control strategy just like Fieldbus devices enabling consistent implementation The logic is configured into the block as text strings and is checked internally by the device itself. This scheme allows configuration to be done from any Fieldbus host configuration tool based on regular device DD and CD files, without any need for a special configuration application and without the need to manage application specific DD and CF files for every block.

3.1.5 Block Access

The access table defines the required parameters.

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Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.1 Page 8 ? Fieldbus Foundation 1994-2002 Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW _4 Index Parameter

VIEW _1 VIEW _2 VIEW _3 VIEW _4

1 ST_REV

2 2 2 2 9 IN_D1 2 2 TAG_DESC 10 IN_D2 2

3 STRATEGY 2 11 IN_D3 2

4 ALERT_KEY 1 12 OUT_D1 2

5 MODE_BLK 4 4 13 OUT_D2 2

6 BLOCK_ERR 2 2

7 ALGORITHM_SEL 4

8 CONTENTS_REV 4

Subtotals 8 2 8 13 From left column 8 2 8 13 Totals 18 2 8 13

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0

3.2 Multivariable Matrix Control

3.2.1 Overview

This application is a simple example of matrix control. Two fluids are mixed so that the desired outlet stream temperature and flow rate are controlled. The matrix is configured inside of one FFB. Because matrix control requires accurate measurements, a second FFB is configured with mathematical expressions to check that mass and energy are conserved. It also checks that there is zero flow if the valve is closed, and that the valve is not closed when the associated flow setpoint is above zero.

3.2.2 Process Diagram

FT1 and FC1 form a loop controlling the associated flow, as does FT2 and FC2. TT1 and TT2 measure the stream temperatures just before they enter the mixing junction and after work done by the valve has changed the temperature. TT3 measures the result of mixing. FT3 is used to determine the amount of heat in the outlet flow.

3.2.3 Field Wiring

The field wiring is H1 F OUNDATION fieldbus. Not shown is a F OUNDATION fieldbus HSE fieldbus linking device, which may be located in any convenient non-hazardous area. The linking device requires two or three H1 Ports and the ability to run the flexible function blocks described below. Field device connection to bus segments depends on plant conditions:

If the field devices are not multiple measurement devices and the plant wiring policy for one bus is one valve and up to two more devices, then the segments could be arranged as follows:

Segment 1: FC1, FT1, TT1, Segment 2: FC2, FT2, TT2, Segment 3: FT3, TT3

If multiple measurement field devices are used, and both flow and temperature can be measured downstream of the valve (valve drop will change the temperature), then FT and TT can be combined in MVT devices as follows:

Segment 1: FC1, MVT1, Segment 2: FC2, MVT2, MVT3

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Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.1 3.2.4 Function Block Diagrams

FFB1 is linked to the process devices as shown above. The cascade links between PID and AO are not shown because they are internal to the control valve instruments. No BKCAL link is shown between FFB1 and the PID blocks because the OUT parameters are calculated. The status of the outputs must be Good Non-cascade to tell the PID that no back calculation is required. There would be contained parameters for the setpoints of the flow and temperature of the outlet stream, in addition to the universal parameters. There may also be contained status and alarm parameters.

The block algorithm is a proprietary matrix calculation that operates on the 6 inputs to produce the 2 outputs that become the setpoints for the process flow controllers. An external proprietary system may be used to generate, modify or delete the algorithm code.

The only supported modes are O/S, Manual and Auto. When the block is in Manual mode it holds whatever value is in the outputs. The outputs may be written with values from the HMI. When the block transitions to Auto mode, the outputs change to the calculated values. A contained parameter may determine how fast they change to new values. It is possible to put one of the PID blocks into Auto mode to ignore the FFB output, perhaps to ‘base load’ one of the input streams. Since there is no BKCAL link, the FFB is unaware that it has no control of one (or both) of the streams, unless it has some logic to detect the difference between the output to the PID cascade input ant the corresponding flow measurement.

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Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0 The following drawing is for another FFB in the same HSE linking device, or a separate device.

FFB2 is linked to the process devices as shown above. These are the same signals used by FFB1 with the addition of a discrete input from each of the control valves. The discrete input is a Boolean that is true when the valve is closed. There would be contained parameters for the status and alarms in addition to the universal parameters.

The block algorithm is a set of simple equations that sum the flows from FT1 and FT2, and compare the sum to FT3. An alarm is generated if the difference exceeds the alarm trip point. Similarly, the heat content of streams 1 and 2 is compared to the outlet heat flow. This generates an alarm if the flow measurements do not have an alarm, because otherwise the heat calculation would be invalid. On those occasions when a valve is closed, as indicated by a true discrete input, then an alarm is generated if the associated flow is not zero. An alarm may also be generated if the flow is zero and the valve is not closed. The PID blocks in the field devices can best generate alarms for deviation between the flow setpoint and the measured flow.

The equations may mix analog and discrete values in mathematical or logical expressions. This can be done with a simplified version of BASIC or any other language of the vendor’s choice. An external proprietary system may be used to generate, modify or delete the algorithm code.

The only supported modes are O/S, Manual and Auto. Manual mode is optional since the block has no outputs, but it can be used to stop alarm generation in the event that something becomes marginal.

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Page 12 ? Fieldbus Foundation 1994-2002 3.2.5 Block Access for FFB1

The access table defines the required parameters. Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW

_4 Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW _4

1 ST_REV

2 2 2 2 38 UPDATE_EVT 2 TAG_DESC 39 BLOCK_ALM

3 STRATEGY 2 40 ALARM_SUM 8 8

4 ALERT_KEY 1 41 ACK_OPTION 2

5 MODE_BLK 4 4 42 ALARM_HYS 4

6 BLOCK_ERR 2 2 43 IN_5_HI_HI_PRI 1

7 ALGORITHM_SEL 4 44 IN_5_HI_HI_LIM 4

8 CONTENTS_REV 4 45 IN_5_HI_PRI 1

9 IN_1 5 5 46 IN_5_HI_LIM 4 10 IN_2 5 5 47 IN_5_LO_PRI 1 11 IN_3 5 5 48 IN_5_LO_LIM 4 12 IN_4 5 5 49 IN_5_LO_LO_PRI 1 13 IN_5 5 5 50 IN_5_LO_LO_LIM 4 14 IN_6 5 5 51 IN_1_DV_HI_PRI 1 15 OUT_1 5 5 52 IN_1_DV_HI_LIM 4 16 BAL_TIME_1 4 53 IN_1_DV_LO_PRI 1 17 OUT_HI_LIM_1 4 54 IN_1_DV_LO_LIM 4 18 OUT_LO_LIM_1 4 55 IN_6_HI_HI_PRI 1 19 OUT_2 5 5 56 IN_6_HI_HI_LIM 4 20 BAL_TIME_2 4 57 IN_6_HI_PRI 1 21 OUT_HI_LIM_2 4 58 IN_6_HI_LIM 4 22 OUT_LO_LIM_2 4 59 IN_6_LO_PRI 1 23 SHED_OPT_2 1 60 IN_6_LO_LIM 4 24 SP_1 5 5 61 IN_6_LO_LO_PRI 1 25 RCAS_IN_1 5 62 IN_6_LO_LO_LIM 4 26 RCAS_OUT_1 5 63 IN_2_DV_HI_PRI 1 27 SP_RATE_DN_1 4 64 IN_2_DV_HI_LIM 4 28 SP_RATE_UP_1 4 65 IN_2_DV_LO_PRI 1 29 SP_HI_LIM_1 4 66 IN_2_DV_LO_LIM 4 30 SP_LO_LIM_1 4 67 IN_5_HI_HI_ALM 31 SP_2 5 5 68 IN_5_HI_ALM 32 RCAS_IN_2 5 69 IN_5_LO_ALM 33 RCAS_OUT_2 5 70 IN_5_LO_LO_ALM 34 SP_RATE_DN_2 4 71 IN_1_DV_HI_ALM 35 SP_RATE_UP_2 4 72 IN_1_DV_LO_ALM 36 SP_HI_LIM_2 4 73 IN_6_HI_HI_ALM 37 SP_LO_LIM_2 4 74 IN_6_HI_ALM 75 IN_6_LO_ALM 76 IN_6_LO_LO_ALM 77 IN_2_DV_HI_ALM 78 IN_2_DV_LO_ALM

Subtotals 58 34 78 38 Subtotals 8 0 8 66 Totals 66 34 86 104

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0

? Fieldbus Foundation 1994-2002. Page 13 3.2.6 Block Access for FFB2

The access table defines the required parameters. Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW

_4 Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW _4

1 ST_REV

2 2 2 2 22 FLOW_DV_HI_PRI 1 2 TAG_DESC 2

3 FLOW_DV_HI_LIM

4 3 STRATEGY 2 24 FLOW_DV_LO_PRI 1 4 ALERT_KEY 1 2

5 FLOW_DV_LO_LIM 4 5 MODE_BLK 4 4 2

6 HEAT_DV_HI_PRI 1 6 BLOCK_ERR 2 2 2

7 HEAT_DV_HI_LIM 4 7 ALGORITHM_SEL 4 2

8 HEAT_DV_LO_PRI 1 8 CONTENTS_REV 4 2

9 HEAT_DV_LO_LIM 4 9 IN_1 5 5 30 FT1_DV_HI_PRI 1 10 IN_2 5 5 31 FT1_DV_HI_LIM 4 11 IN_3 5 5 32 FT1_DV_LO_PRI 1 12 IN_4 5 5 33 FT1_DV_LO_LIM 4 13 IN_5 5 5 34 FT2_DV_HI_PRI 1 14 IN_6 5 5 35 FT2_DV_HI_LIM 4 15 IN_D1 2 2 36 FT2_DV_LO_PRI 1 16 IN_D2 2 2 37 FT2_DV_LO_LIM 4 17 UPDATE_EVT 38 FLOW_DV_HI_ALM 18 BLOCK_ALM 39 FLOW_DV_LO_ALM 19 ALARM_SUM 8 8 40 HEAT_DV_HI_ALM 20 ACK_OPTION 2 41 HEAT_DV_LO_ALM 21 ALARM_HYS 4 42 FT1_DV_HI_ALM 43 FT1_DV_LO_ALM 44 FT2_DV_HI_ALM 45 FT2_DV_LO_ALM

Subtotals 50 2 50 19 Subtotals 0 0 0 40 Totals 50 2 50 59

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.1

3.3 Variable Speed Drive Control

3.3.1 Overview

This application is a partial example of HVAC Air Handler control. The example is centered on the blower and it’s Variable Speed Drive (VSD). YD1 is an inlet damper that is normally wide open, but closes if TSL detects a low temperature after the heating coil due to some failure. YD2 is an outlet damper that closes if YS1 detects smoke in the air duct, perhaps from failure to lubricate the fan bearings. PT1 senses the pressure in the air duct, usually in inches of water or 0.01 Bar. The VSD turns the fan at the speed necessary to maintain a set duct pressure. It is interlocked with the dampers so that it stops quickly if one of them closes. A complete example would include temperature controls.

3.3.2 Process Diagram

3.3.3 Field Wiring

The field wiring is not H1 F OUNDATION fieldbus. It does not carry modulated AC transmissions. Similarly, the instruments are not required to serve as ladder rungs for maintenance technicians and they may use non-standard signal levels. Not shown is a device located on or near the air duct that connects to F OUNDATION fieldbus HSE fieldbus. It also connects to the non-Fieldbus instruments and is a gateway to whatever communication method that is used by the VSD vendor.

3.3.4 Function Block Diagram

FFB1 is linked to the process devices as shown above. It is shown as a field device FD1 and not as a linking device because it has no H1 ports. The labeled input and output parameters are not linked to any FF device. Instead, the bell wire is hooked to screw terminals on FD1 and the converted values are shown to other FF devices with status in the I/O parameters. The VSD connection is not labeled because it is proprietary, and so is invisible to FF devices.

Page 14 ? Fieldbus Foundation 1994-2002

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0 The block algorithm may be user configurable, but is more likely to be developed by the HVAC vendor. The major function is to act as a gateway for the VSD command and status values. These would be displayed in many contained FFB variables. The inpidual discrete and analog I/O points must also be converted. If the external devices have no status information, they can be displayed in contained variables. The HSE Field Device may also have other I/O as required to control temperature, humidity, CO2, etc. or detect clogged filters, vibration, etc.

The block parameter list below contains a set of parameters for a standard SP and Remote Cascade. This applies to the duct pressure setpoint. If this value never changes, it can be made into one simple contained value. If a host computer does not ever set the setpoint, then the 3 remote cascade parameters can be removed. But if a host does set the value of SP, it is much safer to use the cascade initialization handshake. This forces the host software to look at the device before it writes a value. It is essential if the host has an integrating controller that calculates the value to be written.

Standard alarms are provided for IN_1, the duct pressure input. There is a deviation alarm and one level of absolute alarm. There may be alarms without any standard parameters for drive faults and interlock events.

The only supported modes are O/S, Auto and Rcas. There are no outputs that can be set in a Manual mode.

If the block has only Contained parameters, none of the information can be linked to other FF devices.

? Fieldbus Foundation 1994-2002. Page 15

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.1

Page 16 ? Fieldbus Foundation 1994-2002 3.3.5 Block Access for FFB1

The access table defines the required parameters. Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW

_4 Index Parameter VIEW _1 VIEW _2 VIEW _3 VIEW _4

1 ST_REV

2 2 2 2 39 HAND_OFF_AUTO 1 1 2 TAG_DESC 40 START 1 1

3 STRATEGY 2 41 STOP 1 1

4 ALERT_KEY 1 42 CLEAR_FAULT 1 1

5 MODE_BLK 4 4 43 ACTIVE_FAULT 1 1

6 BLOCK_ERR 2 2 44 DRIVE_STATUS 1 1

7 ALGORITHM_SEL 4 45 FREQUENCY 4

8 CONTENTS_REV 4 46 VOLTAGE 4

9 IN_1 5 5 47 CURRENT 4 10 IN_D1 2 2 48 POWER 4 11 IN_D2 2 2 49 TORQUE 4 12 IN_D3 2 2 50 SPEED 4 4 13 IN_D4 2 2 51 VOLTS/HERTZ 4 14 IN_D5 2 2 52 BUS_VOLTS 4 15 IN_D6 2 2 53 POWER_FACTOR 4 16 OUT_D1 2 2 54 HEATSINK_TEMP 4 17 OUT_D2 2 2 55 ACCEL_RATE 4 18 SHED_OPT_1 1 56 DECEL_RATE 4 19 SP_1 5 5 57 MIN_FREQUENCY 4 20 RCAS_IN_1 5 58 MAX_FREQUENCY 4 21 RCAS_OUT_1 5 59 MAX_MOTOR_AMPS 4 22 SP_RATE_DN_1 4 60 CURRENT_LIMIT 4 23 SP_RATE_UP_1 4 61 BRAKING_TIME 4 24 SP_HI_LIM_1 4 62 BRAKING_VOLTS 4 25 SP_LO_LIM_1 4 63 RESTART_TRIES 4 26 UPDATE_EVT 64 RESTART_DELAY 4 27 BLOCK_ALM 65 COMPENSATION 4 28 ALARM_SUM 8 8 66 IN_1_HI_ALM 29 ACK_OPTION 2 67 IN_1_LO_ALM 30 ALARM_HYS 4 68 IN_1_DV_HI_ALM 31 IN_1_HI_PRI 1 69 IN_1_DV_LO_ALM 32 IN_1_HI_LIM 4 33 IN_1_LO_PRI 1 34 IN_1_LO_LIM 4 35 IN_1_DV_HI_PRI 1 36 IN_1_DV_HI_LIM 4 37 IN_1_DV_LO_PRI 1 38 IN_1_DV_LO_LIM 4

Subtotals 42 10 52 48 Subtotals 10 0 46 44 Totals 52 10 98 92

A Variable Speed Drive (also known as a Adjustable Speed Drive in IEC 61800-2, Variable Frequency Drive, Inverter, Adjustable Speed Drive and Adjustable Frequency Drive etc.)

Function Block Capabilities in Hybrid/Batch Applications AG-170 Revision 1.0

? Fieldbus Foundation 1994-2002. Page 17 3.3.6 Additional thoughts on Fieldbus Drives

SP

A motor is traditionally not seen as a process control instrument and therefore the adoption of F OUNDATION fieldbus in a starter or drive still has not happened. However, pumps and fans/blowers are increasingly taking the place of control valves and dampers/louvers and motors also power conveyor belts and other equipment in process plants. Moreover, process plants have many motors for agitators etc. Since process plants only want a single bus technology in their plant, at least as far as possible, Fieldbus drives and starters are highly desirable and there are obviously plenty of applications for it. The versatile communication mechanisms offered by F OUNDATION fieldbus include client/server (acyclic) and scheduled (equidistant, isosynchronous) publisher/subscriber (cyclic) communications as well as report distribution.

The F OUNDATION fieldbus technology essentially consists of two parts: communication networking and a function block programming language for building control strategies. The FFB comes in handy when there is a need to deviate from these two aspects:

- Incorporate devices on foreign networks

- Incorporate devices with foreign programming languages

E.g. the FFB is useful in a gateway to incorporate data from a bus technology such as DeviceNet, and to incorporate a language such as one of the IEC 61131-3 languages e.g. structured text. The drive application makes use of the FFB in both of these capacities. One block is used for network interfacing and another block is used for discrete interlocks. Ideally a native F OUNDATION fieldbus drive shall be used but when an existing drive using other bus technology shall be interfaced a gateway with FFB is necessary. For the purpose of comparison a possible arrangement for a drive transducer block is also studied.

The parameters of an Allen-Bradley 1336 PLUS II were studied as a typical example. This drive has some 334 parameters but many are related to local display and hardwired I/O. Since the purpose of Fieldbus is to eliminate hardwired I/O and local operation instead interfacing data using networking all the hardwiring and conversion related parameters were omitted in the gateway flexible function

block. There are also several values that are "internal" that may not be of interest. This "internal" was arbitrarily decided by precedence set by standard function blocks. E.g. deviation/error and integral contribution values in a PID are not available as parameters in the PID block.

A drive may have a built in process controller but to fully utilize the flexibility of the F OUNDATION fieldbus function block programming language this should be done in a standard function block and therefore the process control parameters are not exposed in the flexible function block. "Logging" of last faults is not done in Fieldbus devices but in the host computer.

3.3.6.1 Flexible Function Block interface to Variable Speed Drive on foreign network

3.3.6.1.1 Setpoint selection (desired speed/frequency)

In conventional drives the desired setpoint (speed/frequency) can be set in many different ways. E.g. by DI selection of pre-set values, 4-20 mA and other analog inputs, potentiometer and pulse etc. and of course by writing the setpoint via communication. In this case a FFB is used to interface to a foreign protocol that ultimately writes the setpoint to the drive. The FFB would receive the setpoint in percentage % e.g. from a PID block or possibly via an AO block in order to avoid problems in the cascade initialization.

These parameters are selected from the Allen-Bradley 1336 PLUS II drive based on parameter spreadsheet and manual downloaded from freely accessible web site.

3.3.6.1.2 Parameters

Parameters in addition to standard FFB parameters

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