1771-2.34, Allen-Bradley Proportional/Integral/Derivative Control (2
Contents
1. General Description ALLEN BRADLEY Allen Bradley Proportional Integral Derivative Control 2 Loop Module Cat No 1771 PD Product Data u ur i E am E in E The Proportional Integral Derivative Control 2 Loop Module Assembly cat no 1771 PD is an intelligent I O Module that performs closed loop PID control The PID module is a process controller It monitors the input process variable compares the input to the desired set point and calculates the analog output based on the control algorithm programmed in the module figure 1 It can be used with a variety of I O devices that operate in the 4 to 20mA or 1 to 5V DC range Product Data Proportional Integral Derivative Control 2 Loop Module Figure 1 PID Closed Loop Control VEVptV Vo BIAS SP Error SP PV BIAS PV Process Variable SP Set Point V Controller Output Vp Proportional Term Kp V Integral Term K Vp Derivative Term Kp Controller Output Controller Gain K Reset Term 1 T Rate Term Ty 11099 You have a choice of control algorithm a A B a ISA Refer to Comparing ISA and A B Algorithms and the end of this data sheet Block transfer programming is used to communicate between the PID module and the PC processor The PC processor writes loop configuration data such as gain constants set points filter values limit and alarm values to the PID module and reads status data such as anal2. C Contact Output Number one normally closed contact held open Peak Voltage 30V Maximum Current 250mA 1985 Allen Bradley Company PLC is a registered trademark of Allen Bradley Company Maximum Power 3VA Digital Inputs from Manual Control Station Two independent inputs for monitoring Power Requirements Backplane or External Digital Circuits 1 2A at 5V DC External Analog Circuits 100mA at 15V DC 100mA at 15V DC Other Loop Update Time 100msec typical Ambient Temperature Ratings Operational 0 C to 60 C 32 F to 140 F Storage 40 C to 85 C 40 F to 185 F Relative Humidity Rating 5 to 95 without condensation Electrical Isolation 1500V rms transient Isolation is achieved by optoelectronic coupling between I O analog circuits and control logic Field Wiring Arm 1771 WF Keying Left connector slot 0 between 8 and 10 18 and 20 Right connector slot 1 between 2 and 4 28 and 30 If all analog outputs and tieback inputs used are selected to current mode the compliance of the analog outputs can be extended from 500 ohms standard compliance to 1250 ohms additional compliance This is achieved by internally referencing the outputs to 15V DC 21 ALLEN BRADLEY II 39 4 ROCKWELL INTERNATIONAL COMPANY With offices in major cities worldwide WORLD EUROPE MIDDLE HEADQUARTERS EAST AFRICA Allen Bradley HEADQUARTERS 1201
3. OT USED Switch Manual X77 Do Reauesst U a ee ae 11098 Additional Compliance The maximum allowable load impedance in current mode using standard 18 compliance is 500 ohms Additional compliance can be established for one or two loops if analog outputs 1 and 2 and tieback inputs 1 and 2 are selected for current mode Additional compliance allows a maximum load impedance of 1250 ohms and is obtained by internally referencing module common to 15V DC Keying Comparing ISA and A B Algorithms Product Data Proportional Integral Derivative Control 2 Loop Module Keying bands should be used to guard against placing another type of module in a module group reserved for the PID module Keying band positions are as follows slot 0 left slot 1 right between 8 and 10 between 2 and 4 between 18 and 20 between 28 and 30 The ISA algorithm and the Allen Bradley algorithm are different although they achieve the same closed loop control By understanding the differences you can convert proportional gain reset and rate values from ISA to equivalent A B gain values ISA Algorithm The equation for PID closed loop control 1s Vo Kc E Kc Ty E dt Kc Tp d E dt Where Kc controller gain 1 T 1 T reset term in repeats per minute Tp rate term in minutes A B Algorithm The equation for PID closed loop control 1s Vo Kp E Ky Edt Kp d E dt Bias Where Kp proportional gain Ky integral gain in inverse se
4. South Second Street Allen Bradley Europe B V Milwaukee WI 53204 USA Amsterdamseweg 15 Tel 1 414 382 2000 1422 AC Uithoorn Telex 43 11 016 The Netherlands FAX 1 414 382 4444 Tel 31 2975 43500 Telex 844 18042 FAX 31 2975 60222 Publication 1771 2 34 October 1985 Supersedes Publication 1771 948 July 1983 As a subsidiary of Rockwell International one of the world s largest technology companies Allen Bradley meets today s challenges of industrial automation with over 85 years of practical plant floor experience More than 11 000 employees throughout the world design manufacture and apply a wide range of control and automation products and supporting services to help our customers continuously improve quality productivity and time to market These products and services not only control individual machines but integrate the manufacturing process while providing access to vital plant floor data that can be used to support decision making throughout the enterprise ASIA PACIFIC CANADA LATIN AMERICA HEADQUARTERS HEADQUARTERS HEADQUARTERS Allen Bradley Hong Kong Allen Bradley Canada Allen Bradley Limited Limited 1201 South Second Street Room 1006 Block B Sea 135 Dundas Street Milwaukee WI 53204 USA View Estate Cambridge Ontario NIR Tel 1 414 382 2000 28 Watson Road 5X1 Telex 43 11 016 Hong Kong Canada FAX 1 414 382 2400 Tel 852 887 4788 Tel 1 519 623 1810 Telex 780 64347 FAX 1 51
5. analog power The module detects internal hardware failures and loss of communication with the PC processor The manner in which the module responds to a detected fault is user selectable Hardware Fault Module response to a detected hardware fault can be selected with internal programming jumper plugs prior to installation table B In the event of a hardware fault programming plug selection causes the module to respond in one of the following ways sets the analog output to the minimum value 4mA or 1V DC holds the analog output to the last value before the fault occurred e sets the analog output to the maximum value 20mA or 5V DC Also when the module detects a hardware fault it automatically transfers control of the loop s to an manual control station if used The output of the manual control station can be controlled manually and overrides the module s output Product Data Proportional Integral Derivative Control 2 Loop Module Loss of Voltage Module response to a detected loss of 5V DC can be selected as well sets analog output to minimum value 4mA or 1V DC sets analog output to maximum value 20mA or 5V DC Outputs go to minimum value if 15V DC is lost Table B Programming Plug Positions Function Choice Plug Position Digital Board hard fault output hold max min E2 LEFT for max min hold last state E2 RIGHT for last state source of 5V DC backplane E10 IN for backplane e
6. 2 Constants Block Read Block Transfer Status Block 11094 Loop data must be loaded initially from the PC processor to the PID module by a power up load enter sequence Thereafter program logic can enable continuous bidirectional communication dynamic status toggle sequence or periodic bidirectional block transfers when the module operates independently of the PC processor Either way the PC processor can continuously monitor the status of the PID module by continuously reading the status block by read block transfers or by examining the module s status monitor byte which does not require block transfers Multiple Block Concept Data block files are areas of the PC processor data table used to store loop control words and loop values The blocks have corresponding storage areas in the PID module Block files required by the PID module are Dynamic block contains values for both loops which may change frequently Once data has been initially loaded into the PID module the dynamic block values can be changed at any time with a single write block transfer The dynamic block contains 10 words for 1 loop operation or 17 words for 2 loop operation Loop 1 Constants Block contains values which seldom change Once data has been initially loaded into the PID module the loop constants can be changed only by initiating a load enter sequence of multiple block Product Data Proportional Integral Derivative Control 2 Loo
7. 9 623 8930 FAX 852 510 9436 PN 955098 65 Printed in USA
8. COMMON OPTIONAL 5VDC Optional 5V OC Power Supply B icat no 1771 P2 or equivalent KB bre tenack inputs can be used to track manual control station ouiput to provide gumpless transfer or can pe used as feedforward inputs A Macule common sgnal level can be selected to either 15V DC COMMON isystem common for standard compliance or 13V DC for additional comphance depending on the application When the manual control statiar s r manual the stator switches these lines tothe MODULE COMMON terminal EI When a request tar manual is made from the PID module or when this relay contact output s used for alarm annunciation this line is switched to the module common signal level for 50 msec For hardware failure or toss of analog power 15V OC this relay output is held at module common urtil the fault is corrected Programming pugs must he positioned for optional AV DC supply 11097 17 Product Data Proportional Integral Derivative Control 2 Loop Module Figure 8 Typical Connections for 1 Loop Control Power Supply PID Module TIER Manual Control TERMINAL IDENTIFICATION Station CAT NO 1771 PDC TERMINAL FUNCTION 17 INPUT CLEAD TIEBACK INPUT 1 TIEBACK INPUT 2 15V DC rasvoc U U UU MANUAL MODE 1 MANUAL MODE 2 MANUAL REQUEST OPT 5V DC COMMON OPTIONAL 5V DC Two Wire Transmitter 4 to 20mA gt PV Input Control Signal Input Control Signal Output Actuator 4 t020mA
9. conds Kp derivative gain in seconds Comparison The ISA algorithm contains dependent variables When you change your controller gain Kc you also change your integral and derivative values The A B algorithm contains independent variables You adjust the proportional integral and derivative terms independently Product Data Proportional Integral Derivative Control 2 Loop Module 20 ISA Algorithm A B Algorithm Controller Gain Kc dimensionless Reset Term 1 T repeats per minute Proportional Gain Kp dimensionless Integral Gain K inverse seconds Rate Term Tp minutes Derivative Gain Kp seconds When using the A B algorithm you must convert the ISA controller gain reset and rate terms to gain values of the A B algorithm Conversion Convert ISA values to A B values as follows Kp Kc K Kp I Tp 60 Kp Kp Tp 60 Example If your desired ISA values are controller gain Kc 1 reset value 1 Tj 5 repeats per minute rate term Tp 3 minutes convert them to A B gain values as follows proportional gain Kp Kc 1 integral gain Ky DS 0 083 60 derivative gain Kp 1 3 60 180 Selecting the Algorithm You select the ISA or A B algorithm by setting a bit in the control word Process Variable Inputs Number process variable input 1 process variable input 2 Configuration Differential Range user selectable 410 20mA 1
10. e as the process variable take the normalized square root of the process variable digitally filter the process variable Standard Control Features select direct or reverse acting control download a set point from the PC processor limit and or set an alarm on the error signal perform error dead band zero crossing set an alarm when the error exceeds the dead band select the A B or ISA PID algorithm select error or error squared conditioning of the proportional and or integral error select whether the derivative function operates on the error or the process variable set an alarm on the proportional term limit and or set an alarm on the integral term a limit and or set an alarm on the derivative term Standard Features for Output Conditioning limit and or set an alarm on the PID algorithm output read the PID algorithm output at the PC processor Product Data Proportional Integral Derivative Control 2 Loop Module override the PID algorithm output from the PC processor interface directly with a manual control station bumpless transfer hold the PID algorithm output for independent loop tuning hold the bias feedforward term for independent loop tuning download an output bias from the PC processor Expanded Features perform scaling on the process variable set point and or error use the tieback as the feedforward input take the normalized square root of the feedforward input add a
11. feedforward offset multiply the feedforward term by a constant perform lead lag filtering on the feedforward term download a feedforward value from the PC processor cascade the output of loop into the set point of loop 2 decouple the VPID output of loop 1 into the feedforward input of loop 2 The module performs anti reset wind up on the integral output term When a limit is set on the PID algorithm output the integral output term is adjusted to compensate for changes in other algorithm output terms A simplified flow chart of the PID loop algorithm figure 3 shows selected standard and expanded loop features Product Data Proportional Integral Derivative Control 2 Loop Module Figure 3 Simplified PID Algorithm Feedforward Input Lead Lag E SP PV SP Process Variable y Digital PY Q Filter BIAS FFV Contro Variable Hardware Hardware Analog Analog input Output 17099 Block Transfer Programming PID module features are selected by setting word values and control bits in data table block files Block files are transferred between the PC processor and the PID module by bidirectional block transfers figure 4 Product Data Proportional Integral Derivative Control 2 Loop Module Figure 4 Multiple Block Concept PC Processor Data Table Dynamic PID Module Block Write Block Transfer Loop 1 Constants Block Write Block Transfer Write Block Transfer Loop
12. iagnostic W61 Loop Status 1 W62 Loop Error 1 4095 Scaled 99990 W63 Read Loop 1 Output 0 4095 W64 Read Analog Input 1 0 4095 W65 Read Process Variable 1 0 4095 Scaled 99990 W66 Read Tieback Input 1 0 4095 W67 Read Feedforward Value 1 9999 W68 Loop Status 2 W69 Loop Error 2 4095 Scaled 99990 W70 Read Loop 2 Output 0 4095 W71 Read Analog Input 2 0 4095 W72 Read Process Variable 2 0 4095 Scaled 99990 W73 Read Tieback Input 2 0 4095 W74 Feedforward Value 2 9999 Storage Requirements Data table storage requirements depend on the number of control loops and on whether expanded features have been selected Data blocks for storing the values of standard and expanded features can be arranged consecutively in the data table A minimum of 33 words is required for one standard loop A maximum of 74 words is required for two expanded loops figure 5 10 Product Data Proportional Integral Derivative Control 2 Loop Module Figure 5 Block File Memory Requirements 1 Standard 1 Expanded 2 Standard 2 Expanded Loop Loop Loops Loops Dynamic Dynamic Block Block Dynamic Dynamic 10 Words 10 Words Block Block 17 Words 17 Words Loop 1 Constants Loop 1 Constants Block Loop 1 Block Loop 1 12 Words Constants 12 Words Constants Block Block 19 Words 19 Words Loop 2 Constants Block Loop 9 12 Words Constants Block 19 Words Status Block Status Block 11 Words 11 Words Status Status Block Bloc
13. in Factory Configured 11096 NOTE Programming plug positions in Table 2 D refer to the board as positioned above 15 Product Data Proportional Integral Derivative Control 2 Loop Module Indicators The front panel LED indicators allow an operator to observe the operating condition of the module The indicators will be on off or flashing table C Table C LED Indicators Indicator State Condition FAULT normal operation red hardware fault RUN normal operation green power up un programmed not running loss of 15V DC STAND normal operation ALONE flashing soft fault yellow toggle loss of 15V DC on block transfer program error all three calibration mode Power Requirements The PID module requires 1 2A at 5V DC from the I O chassis backplane The module also requires 100mA at 15V DC and 100mA at 15V DC from an external supply through the field wiring arm table D Table D 15V DC Power Supply Specifications 15Volts 15Volts Current 100mA 100mA Voltage Tolerance 1 1 Regulation type Series Series Line Regulation for 10V AC input change 0 2 0 2 Load Regulation no load to full load 1 0 1 0 Ripple imVpp imVpp Overvoltage Protection 18 volts 18 volts Current Limit percent of full load 125 125 The source of 5V DC can be an optional external power supply wired to the field wiring arm table E This allows the module to be powered entirely f
14. k 18 Words 18 Words 11095 Display of Data Blocks By placing the data blocks consecutively in the data table they can be displayed conveniently in a single data monitor display where the word numbers and position numbers of the display correspond 11 Product Data Proportional Integral Derivative Control 2 Loop Module Fault Response 12 Programming Considerations The PID module has considerable programming versatility A load enter sequence is used to configure the module with selected features start PID control or to change loop constants Data can be transferred to the module and stored indefinitely in buffer memory until activated by a program logic command Bidirectional block transfers can be used for continuous communication between PID module and PC processor The PC processor reads the status block then writes the dynamic block to the module in the next I O scan Continuous bidirectional block transfer is useful for adaptive control where the PC processor adjusts loop values based on data received by monitoring the process The PID module is capable of operating independently without continuous block transfer communication with the PC processor Once the module has been initialized the module s general status can be monitored continuously through the status monitor byte without block transfers The status monitor byte reports the module s detection of a module hardware fault loss of input or loss of
15. l cause the outputs of other modules in the same chassis to be de energized when they detect a fault The response for each loop can be selected independently for a hardware or communications fault The PID module is a dual slot module that occupies both slots of a module group The front panel contains three LED indicators and a write on label to record I O ranges and the last date of calibration Internally the module contains a digital and an analog printed circuit board The analog board is located beneath the module cover containing the label that identifies the connections to the field wiring arm Internal Selections The PID module can accommodate a wide variety of applications This is made possible by positioning a number of programming plugs inside the module Selectable functions and corresponding programming plugs on both circuit boards are listed in table B Programming plug locations on the analog circuit board are shown in figure 6 Product Data Proportional Integral Derivative Control 2 Loop Module Figure 6 Programming Plug Locations Analog Board Stake Pins E1 IV ELLI Coc amp 16 3 O EAEE or 17 En O E13 op a IV Ce es IN or OUT E24 En Backplane e E22 E21 External s 3 ee ee IN or OUT IN or OUT IV oe an E5 eee F3 O v O Compliance IN or OUT Era Additional Standard er 7 15V DC eee OV DC E14 E15 eco E7 4 E48 IN or OUT Egk e v E1199 oF E12 99 E8 Plug P
16. og input values analog output values alarm limits and diagnostics from the PID module The PID module can be used with any Allen Bradley PC processor that has block transfer capability and uses 1771 VO Product Data Proportional Integral Derivative Control 2 Loop Module The PID module has five levels of fault tolerance If communication with the PC processor is lost or withheld the module can operate alone in soft fault mode using the last values transferred from the PC processor If a fault in module hardware is detected the module automatically sets the output to a predetermined value and generates a signal to transfer control to an optional user supplied manual control station When a manual control station is used the manually controlled output overrides the output set by the module Control can be returned to the PID module by a bumpless transfer that prevents an undesirable output surge Another level of fault tolerance is the module s response to loss of voltage If 5V DC is lost outputs go to a predetermined maximum of minimum value If 15V DC is lost outputs go to minimum value Lastly the PID module can operate from a power supply that is independent of the I O chassis power supply An overview of a PID module control system is shown in figure 2 Once properly configured the PID module can operate independently of the PC processor Or the PID module PC processor combination can perform adaptive control where
17. p Module transfers The loop constants block contains 12 words for standard features or 19 words for standard and expanded features Loop 2 Constants Block similar to Loop 1 Constants Block Status Block is used to report the current status of the PID module and any alarm condition detected by the module The status block also prompts the next write block transfer of a dynamic block or loop constants block The status block contains 11 words for 1 loop operation or 18 words for 2 loop operation A summary of the words used to store feature values and associated control bits is listed in table A Table A Control and Value Words Dynamic Block Word Title Wo1 Master Control Word W02 Control Word Wo3 Dynamic Block Start Address W04 Loop 1 Block Start Address W05 Set Analog Output 1 W06 Set Point 1 Scaled W07 Proportional Gain 1 W08 Bias 1 Wo9 Process Variable 1 W10 Feedforward Input 1 W11 Loop 2 Block Start Address W12 Set Analog Output 2 W13 Set Point 2 Scaled W14 Proportional Gain 2 W15 Bias 2 W16 Process Variable 2 W17 Feedforward Input 2 4095 0 4095 0 4095 99990 0 9999 9999 0 4095 4095 Product Data Proportional Integral Derivative Control 2 Loop Module Table A Control and Value Words continued Loop 1 Constant Block Word Title Title Range W18 Loop Control Word A W19 Loop Control Word B W20 Input Filter Time Constant 1 0 999 9 W21 Maximum Nega
18. rom power supplies independent of the backplane 16 Wiring Table E 5V DC Optional Power Supply Specifications Voltage at field wiring arm Current Voltage regulation sum of all deviations due to line load and ripple Rise time to 4 75V DC Product Data Proportional Integral Derivative Control 2 Loop Module 5V DC 5 05V DC 1 2A 0 15V DC 10ms Terminal identification and connections to the module are summarized in figure 7 Typical wiring less shielding for I loop control with a manual control station is shown in figure 8 Proper shielding is essential to minimize coupling of electrical noise to the PID module The optimum grounding point s will vary between inputs and outputs and voltage or current devices Refer to the PID Module User s Manual publication no 1771 6 5 9 for proper shielding of input and output devices Figure 7 Terminal Identification and Connections TERMINAL IDENTIFICATION CAT NO 1771 PDC TERMINAL FUNCTION INPUT 1 LEAD INPUT 1 LEAD Process Variable 1 Process Variable 2 Tieback Input iQ Tieback Input 20 Control Element 1 Modute Common Control Element 2 ANALOG OUTPUT 1 11 MODULE COMMON ANALOG OUTPUT 2 15V DC 115V DC COMMON 15 BC Required 15V DC Power Supply cat no 1770 P1 1778 P2 or equivalent E MANUAL MODE 2 El MANUAL REQUEST p OPT 5V DC
19. the PC processor can continually adjust the PID module s control algorithm based on process changes monitored by the PC processor In addition PID modules can be used with PC processors in distributed control systems using the data highway Figure 2 System Overview PC Processor 1771 P1 or 1771 PD Optional Supply Adapter Module User Supplied Manual Control Station Manual Request e Man Auto Status a Analog Output V Tieback Input 1770 P1 Supply Analog Input PV I 15V DC 100 mA 5V DC 1 2A Optional Supply 11092 Product Data Proportional Integral Derivative Control 2 Loop Module Loop Features The PID module can control one or two PID closed loops The two loops can be independent or linked together by an advanced control function such as cascade or decoupling Expanded loop features can be chosen in addition to standard features to suit the application All features are selectable by settings bits in the data table with the exception of the I O range the source of 5V DC and the fault response to a hardware failure or loss of 5V DC which are selected using internal configuration plugs Write block transfers to the module allow program logic to enable the following features Standard Features for Input Conditioning detect the loss of process variable input read the process variable at the PC processor substitute a value calculated by the PC processor for us
20. tive Error 1 0 4095 W22 Maximum Positive Error 1 0 4095 W23 Dead Band 1 0 4095 W24 Integral Gain 1 0 999 9 W25 Derivative Gain 1 0 9999 W26 Integral Term Limit 1 0 9999 W27 Derivative Term Limit 1 0 9999 W28 Minimum Output Limit 1 0 4095 W29 Maximum Output Limit 1 0 4095 W30 Loop 1 Expanded Control Word W31 Minimum Scaling Value 1 99990 W32 Maximum Scaling Value 1 99990 W33 Feedforward Offset 1 0 9999 W34 Feedforward Gain 1 0 9999 W35 Lead Time Constant 1 0 999 9 W36 Lag Time Constant 1 0 999 9 Loop 2 Constants Block Word Title Range W38 Loop 2 Control Word A W39 Loop 2 Control Word B W40 Input Filter Time Constant 2 0 999 9 W42 Maximum Negative Error 2 0 4095 W42 Maximum Positive Error 2 0 4095 W43 Dead Band 2 0 4095 W44 Integral Gain 2 0 999 9 W45 Derivative Gain 2 0 9999 W46 Integral Term Limit 2 0 9999 W47 Derivative Term Limit 2 0 9999 W48 Minimum Output Limit 2 0 4095 W49 Maximum Output Limit 2 0 4095 W50 Loop 2 Expanded Control Word W52 Minimum Scaling Value 2 99990 W52 Maximum Scaling Value 2 99990 W53 Feedforward Offset 2 0 9999 W54 Feedforward Gain 2 0 9999 W55 Lead Time Constant 2 0 999 9 W56 Lag Time Constant 2 0 999 9 Product Data Proportional Integral Derivative Control 2 Loop Module Table A Control and Value Words continued Status Block Word Title Range W57 For Future Use W58 Alarm both loops W59 Next Block Start Address W60 Loop Time D
21. to 5V DC Digital Resolution 12 bit binary 1 part in 4095 Accuracy 0 1 of range at 25 C Input Impedance 250 ohms current 10 megohms voltage Common Mode Rejection Ratio 70dB DC Common Mode Voltage Range 200V with respect to module common Common Mode Input Resistance 2 5 megohms Input Frequency Response 3dB at 1kHz Maximum Allowable Input 30mA current 125V DC voltage Temperature Coefficient 50 ppm C Tieback Inputs Number Tieback input 1 tieback input 2 Configuration Single ended Range user selectable 410 20mA 1t0 5V DC Digital Resolution 12 bit binary 1 part in 4095 Product Data Proportional Integral Derivative Control 2 Loop Module Specifications Accuracy 0 1 of range at 25 C Input Impedance 250 ohms current 4 7 megohms voltage Maximum Allowable Input 30mA current 25V rms voltage Temperature Coefficient 50 ppm C Analog Outputs Number analog output 1 analog output 2 Configuration Single ended Range user selectable 4 to 20mA With output common internally referenced to power supply common the output will drive up to a 500 ohm load over the full current range 1to 5V DC 500 ohms minimum load resistance 10mA maximum load current Digital Resolution 12 bit binary 1 part in 4095 Accuracy 0 1 of range at 25 C Temperature Coefficient 50 ppm
22. xternal E10 OUT for external Analog Board hard fault output 1 maximum minimum E5 OUT for max IN for min 2 maximum minimum E4 OUT for max IN for min output range E3 E6 E8 as shown in figure 6 E1 E2 E7 as shown in figure 6 E15 IN for I OUT for V E14 IN for I OUT for V input range N lt lt lt lt tieback input E11 IN for I OUT for V E12 IN for I OUT for V compliance standard additional E18 as shown in figure 6 E21 E22 IN for standard OUT for additional source of 5V DC back plane external E23 E24 as shown in figure 6 Note The current range is 4 to 20mA the voltage range is 1 to 5V DC 13 Product Data Proportional Integral Derivative Control 2 Loop Module Hardware 14 Communications Fault The PID module detects the loss of communication with the PC processor soft fault Program logic enables the module to respond in one of the following ways in response to a soft fault sets the analog output to the minimum value 4mA or 1V DC e holds the analog output to the last PID algorithm value before the soft fault occurred performs PID control based on the last values transferred to the PID module before the soft fault occurred sets the analog output to the maximum value 20mA or 5V DC Switch position 1 on the last state switch assembly I O chassis backplane must be set to the position for the soft fault response to operate Note that this wil
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