Rockwell Automation 1771-PD User Manual

AllenBradley

Proportional/Inte gral/Derivative

User

Control (2-Loop) Module

(Cat.

No. 1771-PD)

Manual

Introduction 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Assembly and Installation 21. . . . . . . . . . . . . . . . . . . . . . . . .

General 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Hardware Description 21 Internal Selections 22 Manual

Control Station Interface Input Power Supply Requirements 219 Installation Practices 222 Chassis Considerations 223 Internal Fusing 224 Recommendations for Installing or Removing Modules 224 Keying 225 Power Supply Specifications 227 Module

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Specifications

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229. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Programming 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operational Overview 32 Word

and Bit Definitions Algorithm Flow Chart 351 Block Transfer Programming 351 Programming Considerations 370 Expanded Features 377 Programming Recommendations for Startup 388

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38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Troubleshooting 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LED Troubleshooting Guide 41 Program Troubleshooting Guide 41 Calibration 51 General 51 Test Preparation 52 Calibration Program 55 Calibration Procedures 59

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Equipment

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Table of Contentsii

Worksheets A1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Application Example 1, Continuous Block Transfer B1. . . . . .

General B1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Example

Application

B1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Application Example 2, Periodic Block Transfer C1. . . . . . . . .

General C1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Example

Application

C1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Summary Word and Bit Tables D1. . . . . . . . . . . . . . . . . . . . . .

Comparing ISA 1771PD Algorithms E1. . . . . . . . . . . . . . . . .

Algorithm Flow Chart F1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction

Chapter

General

The Proportional/Integral/Derivation 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. The PID module monitors the analog input process variable, compares the input to the desired set point, and calculates the analog output control variable based on the control algorithm programmed in the module. The PID module has the hardware inputs and outputs and microprocessor to perform PID control.

The PID module assembly consists of:

1 Proportional/Integral/Derivation Control (2-loop) Module (cat. No.

1771-PD)

1 Field Wiring Arm (cat. No. 1771-WF)

The PID module can control up to two closed loops such as flow, temperature, pH, and level. Advanced control features include cascade, feedforward, scaling, square root, error squared, digital and led/lag filtering. The PID module can directly interface with an optional user supplied manual control station. Transition from manual to automatic control can be performed with bumpless transfer. ranges can be selected for each loop to either +1 to +5V DC or +4 to +20mA.

[1]

Input and output

The PC processor uses block transfer programming to communicate with the module. The PC processor writes loop configuration parameters such as gain constants, set points, digital filter values, limits, alarm points to the PID module and reads status information such as analog input values, analog output values, limit alarms 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 the 1771 I/O structure.

When using the Mini-PLC-2 and PLC-2/20 processors, programming will be more lengthy because these processors do not have the block format instructions which permit shorter programs and easier data monitoring.

[1]

Bumpless

means a smooth transition from manual to automatic control.

transfer

, as defined in Fundamentals of Process Control Theory by Paul W

. Murril,

11

Chapter 1

Introduction

Capabilities

The PID module can control one or two PID closed loops. The two loops can be independent or linked together by and advanced control function such as cascade or decoupling. Expanded loop features can be chosen in addition to standard features to suite the application. All features are software selectable with the exception of the I/O range, the source of +5V DC, and the fault response to a hardware failure (which are selected using internal programming 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 from the PC processor for the process variable take the 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 download a dead band value from the PC processor perform error dead band (zero crossing) set an alarm when the error exceeds the dead band select the control mode: proportional only, integral only, proportional

and integral, proportional and derivative, or all three

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 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 download an output value 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/feed forward term for independent loop tuning

12

Chapter 1

Introduction

download an output bias from the PC processor

Expanded control features

perform scaling on the process variable, set point and/or error set minimum and maximum scaling values use the tieback as the feedforward input take the square root of the feedforward input add a 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 1 into the set point of loop 2 decouple the VPID output of loop 1 into the feedforward input of loop

These features including integral term anti-reset wind-up are described in chapter 3.

PID Algorithm

An algorithm is a step-by-step procedure. The purpose of the PID algorithm is to maintain the process at the desired setpoint. A diagram of PID closed loop control is shown in Figure 1.1a.

The PID module has many features. Select only those features that are required for the particular application. Major control functions are shown in Figure 1.1b. Refer to figure 3.15 for a detailed algorithm flow chart. This flow chart shows the relationship of the user-selectable features.

PID modules (rev C or later) let you select the ISA or Allen-Bradley algorithm. Refer to appendix E for a comparison of algorithm values.

Hardware Description

The PID module has four analog inputs and two analog outputs each with 12-bit binary resolution. Each input and output can be individually selected to either the +4 to +20mA or +1 to +5V DC range without recalibration. The selection is made with internal programming plugs. Each loop has one process variable input, one tieback input and one analog output associated with it. The tieback analog input is used to track the analog output of the manual control station to permit bumpless transfer. Each loop uses one discrete input to track the status of the optional manual control station. A contact output is used to switch the

13

Chapter 1

Introduction

manual control station of both loops to manual control. The module’s analog inputs can be read and outputs can be set by the PC processor.

The PID module can draw its +5V DC operating power from either the chassis backplane power supply or from a user-supplied +5V DC power supply through the field wiring arm. The external power supply option permits a more fault tolerant system by allowing the PID module to be powered independently. The PID module also requires +15V DC power for the analog circuitry.

Typical PID hardware and signal paths are shown in Figure 1.2.

14

Chapter 1

Introduction

Error=SP-PV

PV = Process Variable SP = Set Point

AB ISA

V = Control Variable

= Proportional Term K

VI = Integral Term K VD = Derivative term K

Figure 1.1 Simplified

VP + VI + V

Control Variable

Controller Gain K Reset Term 1/

Rate Term T

PID Algorithm

BIAS

+ VI + V

V = V

D +

BIAS

P r o c e s s

a) PID Closed Loop Control

Process Variable

A/D

Hardware

Analog

Input

b) Major Control Functions

Digital

Filter

Error=SP-PV

S P

Feedforward Input

Lead Lag

BIAS

PID

(FFV) Control Variable

D/A

Hardware

Analog Output

11099

15

Chapter 1

Introduction

Figure 1.2

Overview

System

1771 –P1 Supply

PC Processor or Adapter

Block Transfer

1770 –P1 supply

15V DC

–

100mA

1771 –PD Module

+5V DC

1.2A Optional Supply

Manual Request

Man/Auto Status

Analog Output (V)

Analog Input (PV)

Optional User Supplied Manual Control Station

Tieback Input

r o c e s s

11092

16

Programming Description

The PID algorithm can be adapted to the particular control application by selecting desired features. The features and parameter values are chosen and stored in the PC processor data table. The PC processor transfers to the PID module data table blocks which contain the feature selections and parameter values. The module uses the values to establish its operational characteristics. The PC processor can read the module status by transferring information from the module into the data table. Communication between PC processor and PID module is performed by block transfer programming.

Levels of Fault Tolerance

The module has five levels of fault tolerance.

The first level occurs when the PID module is operating properly but a loss of communication with the active PC processor occurs. The module enters a mode of operation defined as soft fault. A soft fault occurs when:

Chapter 1

Introduction

PC processor operation is changed from run mode to program or

test mode a PC processor fault occurs a communications cable break occurs between the PC processor

and the I/O chassis

Each loop can be programmed independently to one of the following responses when a soft fault occurs:

set the analog output to minimum value (+4mA or +1V DC) holds the analog output to the last value before the soft fault occurre performs PID control based on the last values transferred to the module

before the soft fault occurred.

sets the analog output to maximum value (+20MA or +5V DC)

The second level of fault tolerance is how the module sets its outputs in response to a hard fault. A hard fault occurs when the module detects a failure of its microprocessor or its self-diagnostics. Internal programming plugs are used to select the manner in which the PID module can respond if a hard fault should occur:

sets analog output to minimum value (+4MA or +1V DC) holds analog outputs at the last value before the fault occurred sets analog outputs to maximum value (+20mA or +5V DC)

Note: These hard fault responses cannot be ensured if a component in the analog output circuit should fail.

A manual control station can be connected between the PID module analog output and the controlled element of the process. Control of the output can be switched manually to the manual control station by a switch at the station. Manual control at the station overrides the PID module’s output.

The third level of fault tolerance is automatic switching of control to the manual control station when a hard fault occurs. A relay contact in the PID module closes automatically (manual request), putting the station in control. The module’s output is overridden by the station output.

The fourth level of fault tolerance is the module’s response to loss of +5V DC. Outputs respond as if a hard fault occurred (a or C above, but not b). The same programming plug configuration selects the module’s response. If +15V DC is lost, analog outputs go to minimum value, regardless.

17

Chapter 1

Introduction

The last level of fault tolerance results from powering the module from external +5V DC and +

l5V DC power supplies, independent of I/O

chassis backplane power, through the field wiring arm.

Application in Control Systems

The PID module performs closed loop control. Once programmed, it can operate independently of the PC processor. System status and alarm information can be reported to the PC processor to ensure safe system performance.

Redundant control is another alternative. PID modules could serve as back-up to a PC processor performing the PID loop algorithms. The PC processor can control many complex and interaction loops using PID modules for analog inputs and outputs. The complex algorithm could be subdivided into individual loop algorithms stored in the PID modules operating as analog I/O modules. In the event of a PC processor failure or loss of communication between PC processor and a PID module, the soft fault mode of the PID module would allow it to automatically control its loops according to the PID loop algorithms stored in its memory if the appropriate soft fault response had been selected.

18

Figure 1.3

of Distributed Control

Levels

Chapter 1

Introduction

Data Highway

1771 - PD

r o c e s s

1771 - PD

r o c e s s

Manual Control Station

r o c e s s

1771 - PD

r o c e s s

r o

c e

r o c e s s

11100

The PID module can also be used in a system with adaptive control based on the PC processor’s ability to constantly adjust the control algorithm in the module.

19

Chapter 1

Introduction

Finally, PID modules can be used in distributed control schemes. The data highway can be used to link PC processors which are controlling PID modules. Figure 1.3 shows the various levels of distributed control.

Manual Overview

The remainder of the manual explains different aspects of PID module operation.

Chapter 2 - Assembly and Installation contains hardware information

including wiring diagrams, programming plug selection of I/O ranges and compliance, installation and keying, wiring diagrams and specifications of the PID module and power supplies.

Chapter 3 - Programming contains detailed explanations of all the

software selectable features.

Chapter 4 - Troubleshooting contains helpful troubleshooting

information.

Chapter 5 - Calibration presents the procedure for recalibrating the PID

module.

Appendix A contains recots which are helpful when selecting features

and programming the module.

Appendices B and C provide sample ladder diagram programs based on

sample applications.

Appendix D contains summaries of value words and control bits used

when programming.

Appendix E shows how to convert ISA standard values to 1771-PD

gain values.

Appendix F is an enlarged algorithm flow chart for your convenience.

110

Chapter

Assembly and Installation

General

Hardware Description

The PID module must be configured internally and wired externally to suite the conditions under which the module will be used. Module and power supply specifications are listed at the end of this chapter.

The PID module is a dual-slot module. The left front panel contains three LED indicators, the right front panel contains a write-on label that can be used to record the voltage or current range and the most recent date of calibration. An 18 terminal field wiring arm is connected to the lower right front of the module for I/O and power connections. The label on the right cover plate identifies the terminals of the field wiring arm.

Diagnostic Indicators

Front panel indicators (Figure 2.1) allow an operator to observe the operating condition of the module. The indicators will be on, off or flashing (Table 2.A).

Figure 2.1 Diagnostic

Indicators

FAULT

RUN

STAND ALONE

21

Chapter 2

Assembly and Installation

Table 2.A Indicator

Indicator State Condition

FAULT

(red)

RUN

(green)

STAND

ALONE

(yellow)

OFFONNormal operation.

Flashing

OFF

Toggle

OFF

Flashing

Diagnostics

Hardware fault. Analog outputs are held at either last state, minimum or maximum value as determined by the userselected programming plugs. If this indicator is on, the other indicators are not valid

Normal operation

PID module is initially powered (unprogrammed and is waiting for data from the PC processor

PID module is not in the normal run mode.

Analog power (+ and RUN indicators are alternately toggling on and of

Normal operation

The module is in soft mode and is controlling PID loops independently Processor.

15V dc) is lost when ST

. It is not communicating with an active PC

AND ALONE

NOTE: All indicators are of

Internal Selections

NOTE: Disconnecting the field wiring arm will interrupt PID control.

Toggle

Analog power (+ and RUN indicators are alternately toggling on and of

A programming error is causing a block transfer communication error

f when in calibration mode.

15V dc) is lost when ST

AND ALONE

In order to accommodate a wide variety of applications, a number of programming (jumper) plugs must be correctly positioned inside the PID module. The following functions are user-selectable using the programming plugs:

output range: +4 to +20mA or +1 to +5V dc input range: +4 to +20mA or +1 to +5V dc tieback input range: +4 to +20mA or +1 to +5V dc, if used current output compliance: standard or additional hard fault output: hold last value or max/min value output for loss of +5V dc: max or min value +5V dc source: backplane or external

22

Chapter 2

Aseembly and Installation

Calibration of the I/O ranges should be checked yearly to maintain specified accuracy.

Programming Plugs and Locations

The PID module contains two printed circuit boards. The left-hand board is the digital board, the right-hand board is the analog board.

Programming plugs are located on both the analog and digital circuit boards inside the PID module. Typically they stand higher than the surrounding components on the circuit board. The programming plug locations are labeled E1 through E24 on the analog board. The only user-selectable programming plugs on the digital board are E2 and E10.

Some of the programming plug locations are factory configured and must remain in the configuration except during calibration. They are called out as factory configured in the programming plug position tables and in the figures which show their locations.

User-selectable plug locations have either two or three pins per plug. Programming plugs electrically connect two pins. The plug can be placed over the required pins or stored by placing the plug over a single pin, electrically floating.

Programming Plug Selection

Programming plugs should be set with care after decisions are made which govern their placement. The following procedure will be helpful to ensure that all the programming plugs are properly set. The procedure consists of 5 parts.

a. Select digital board features. Record features on Table 2.B

b. Select analog board features. Record features on Table 2.C.

c. Record the position on analog plugs by completing Table 2.D.

d. Set programming plugs on the digital board using Table 2.B.

e. Set programming plugs on the analog board using Table 2.D.

23

Chapter 2

Assembly and Installation

Selection Procedure (Part A)

Begin with digital board features using Table 2.B.

1. The hard fault response of the module is selected first. A hard fault

occurs when a module failure is detected in the event of a failure, the analog output will either maintain the last value or will be set to the minimum or maximum value. A single choice is made for both outputs as to whether they hold last value or go to minimum/maximum.

Select hold last value or go to minimum/maximum for the hard fault response. Record your selection on Table 2.B by circling RIGHT for hold last value or LEFT for minimum/maximum.

NOTE: If hold last value is selected for hard fault, output 1 and output 2 must still be selected for minimum or maximum. The selection determines the state of outputs at module power-up (green LED flashing) until the load/enter sequence is complete, or power-down of +5V dc. See Table 2.C.

Table 2.B Programming

[1]

E3 through E9

E10

[1]

The selection for E2 affects both outputs the same. The choice of minimum value or maximum value for the hard fault output must be made on the analog board regardless of the choice of E2. (see text and analog board plugs E4 and/or E5).

Plug Selections: Digital (lefthand) Board

Location Function Position

Factory Configured

Hard fault response:

Hold last value Minimum/maximum value

Factory Configured

Source of +5V dc

Backplane External supply

OUT

RIGHT LEFT

See figure 22

IN OUT

24

Chapter 2

Aseembly and Installation

Table 2.C Programming Plug Selections: Analog (righthand) Board

Choose and record the required conditions for each function below.

Function Condition

Output

1: Hard Fault

or Loss of +5V dc

Output 2: Hard Fault or Loss of +5V dc

Analog Input 1

Analog Output 1

ieback Input 1

Analog Input 2

Analog Output 2

ieback Input 2

Compliance

Source of +5V dc

Minimum V Maximum V

Voltage Current

Standard (500 ohms: COMMON @ OV) Additional (1250 ohms: COMMON @  15V)

Backplane External Supply

alue

25

Chapter 2

Assembly and Installation

Table 2.D Programming Plug Positions: Analog (righthand) Board

Mark the programming plug position for each function below.

Location Function Position

E1 Output

Output 2, voltage mode

E11 T

Output 2, current mode

Output 2, voltage mode

Output 1, current mode

Output 1, voltage mode

Hard fault* output 2, minimum Hard fault* output 2, maximum

Hard fault* output 1, to minimum

Hard fault* output 1, to maximum

Output 1, voltage mode

Output 1, current mode

Output 2, voltage mode

Output 2, current mode

Output 1, voltage mode

Output 2, current mode

Factory configured

ieback 1, current mode

ieback 1, voltage mode

2, current mode

LEFT

RIGHT

LEFT

RIGHT

LEFT

RIGHT

OUT

TOP

BOTTOM

TOP

BOTTOM

TOP

BOTTOM

RIGHT

OUT 1

26

E12 T

E13

E14

E15

E16,17

E18

[2]

E19, 20 Factory configured

E21

[2]

E22[ 2 ]

ieback 2, current mode

ieback 2, voltage mode

Factory configured

Input 2, current mode

Input 2, voltage mode

Input 1, current mode

Input 1, voltage mode

Factory configured

Additional compliance (15V dc)

Standard compliance (OV dc)

Additional compliance Standard compliance

Additional compliance

Standard compliance

OUT 1

LEFT

OUT 1

BOTH IN

LEFT

RIGHT

BOTH IN

OUT 1

OUT [1]

Chapter 2

Aseembly and Installation

Location PositionFunction

E23

[3]

E24

[3]

*or loss of +5V dc

[1]

IN refers to connecting the two pins together. OUT refers to storing the programming plug by

placing it over a single pin, electrically floating.

[2]

The positions of programming plugs E18, E21 and E22 must be the same.

[3]

The positions of programming plugs E23 and E24 must be the same.

NOTE

: Use figure 2.3 to locate the programming plugs.

+5V dc from backplane

+5V dc from external source

+5V dc from backplane

+5V dc from external source

TOP

BOTTOM

TOP

BOTTOM

2. Select source of +5V dc as the backplane or external supply. Record

your selection on Table 2.B by circling IN for backplane or OUT for external.

Part B)

Select and record the analog board features on Table 2.C using the following procedure.

Select the modules’ response to a hard fault or loss of +5V dc. Choose maximum or minimum value for either output 1 or 2. Make these selections regardless of how you set E2 in Table 2.B. If you selected hold last value, you still must select maximum or minimum value for each output. Outputs go to the selected value at module power-up (green LED flashing) until the load/enter sequence is complete, or when powering down +5V dc.

1. Choose minimum or maximum response of output 1 for hard fault or

power-down of +5V dc.

2. Choose minimum or maximum response of output 2 for hard fault or

power-down of +5V dc.

3. Choose analog input 1 as either voltage mode (+1 to 5V dc) or

current mode (+4 to +20mA).

4. Choose analog output 1 as voltage or current.

27

Chapter 2

Assembly and Installation

5. Choose the tieback input 1 as voltage or current.

If tieback input 1 is wired to track the manual control station associated with analog output 1, then both tieback input 1 and analog output 1 must be selected to the same mode of either current or voltage.

6. Choose analog input 2 as voltage or current.

7. Choose analog output 2 as voltage or current.

8. Choose tieback input 2 as voltage or current.

If tieback input 2 is wired to track the manual control station associated with analog output 2, then both tieback input 2 and analog output 2 must be selected to the same mode of current or voltage.

9. Choose compliance as standard or additional.

Compliance is defined as the maximum allowable load impedance in the current mode. The standard compliance for the PID module is 500 ohms. Additional compliance can be established for one or two loops, only if analog outputs 1 and 2 and tieback inputs 1 and 2 are all selected for the current mode.

(The condition on tieback inputs is required only when they are tracking outputs.) Additional compliance allows a maximum load impedance of 1250 ohms. Additional compliance is obtained by internally referencing the MODULE COMMON terminal to the -15V dc terminal. Choose standard or additional compliance and record in Table 2.C. The choice may affect the power supply requirement for input devices as described in section titled External Connections.

10.Choose the source of +5V dc as either the backplane or external

supply.

11.Review all the choices made in table 2.C before continuing.

28

Chapter 2

Aseembly and Installation

Part C)

Record the required programming plug positions on table 2.D using your selections on table 2.C for reference. Select LEFT/RIGHT, IN/OUT or TOP/BOTTOM so that Table 2.D has a position defined for every E location.

1. Using your selections inTable 2.C for reference, mark the

corresponding plug positions in the right-hand column of Table 2.D Table 2.D. For example, if the required condition for output is minimum value due to hard fault or loss of +5V dc, mark the IN position in Table 2.D for E5.

Part D)

Set programming plugs E2 and E10 on the digital board using Table 2.B and the following procedure:

1. Remove the unmarked left cover plate to gain access to the digital

circuit board.

2. Refer to Figure 2.2 to identify the location of the user-selectable and

factory configured programming plugs.

3. Set programming plugs E2 and E10 according to the functions

circled in Table 2.B.

4. Verify that the factory configured programming plugs are installed as

shown in Figure 2.2

5. Set the completed digital board, cover, and screws to one side.

Part E)

Set the programming plugs on the analog board usingTable 2.D and the following procedure:

1. Remove the right cover (with the terminal identification label) to

gain access to the analog circuit board.

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Chapter 2

Assembly and Installation

2. Refer to Figure 2.3 to identify the locations of the user-selectable and

factory configured programming plugs.

3. Starting at E1, read down table 2.D and set each programming plug

on the analog board.

CAUTION: The programming plugs at location E11 and E12 could interfere with the front cover flange when the analog board is re-assembled to the rest of the module. This could happen when either the E11 or E12 programming plug is placed in the OUT (floating) position. When either is required to be in the OUT position, place the floating side of the E11 plug toward the center of the board and the floating side of the E12 plug toward the top of the board.

4. Verify that factory configured programming plugs are in their correct

positions.

5. Re-assemble the PID module. Typically it is easier to re-assemble

the digital board and cover before the analog board and cover. Observe caution when re-assembling the analog circuit board. Be certain that the three stake pins located on the lower corner of the board mate with their respective sockets on the digital board. Carefully align these connections before aligning and tightening the screws on the module cover.

Record the I/O range selections on the module’s write-on label.

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Chapter 2

Aseembly and Installation

Backplane Connector

StakePin

Connector

Figure 2.2 Programming

Hold Max

Min

Plug Locations (Digital Board)

Backplane Connector

No Plug

Hold Last State

E10

Diagnostic Indicators

Jumper Test Pins

Programming Plug

Factory Configured Plug

11101

Backplane

External

E24E

Stake Pins

E19 E

* *

E22E

IN or Out

Figure 2.3 Programming Plug Locations (Analog Board)

Additional (-15V dc)

Compliance

E18

Standard (0V dc)

IN or OUT

E14

E15

IN or OUT E11 E12

IN or OUT

E6 V

Plug

Pi Factory Configured

11096

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Chapter 2

Assembly and Installation

External Connections

Terminal identification of the PID module’s field wiring arm and general connections are shown in Figure 2.4. Typical I/O connections for a single closed loop configured in current mode are shown in Figure 2.5. The remaining three figures show typical connections to input and output devices and control mode connections to a manual control station.

Figure 2.6 shows typical connections to input devices without a manual control station. When an input loop is configured in current mode, the input impedance of all devices connected in series must be considered when selecting the input power supply. the input loop could contain one or more recording devices (250 ohms) and/or a manual control station (100 ohms) in addition to the PID module (250 ohms) and the current transmitter. Current transmitters typically require at least 18V dc. Voltage transmitters, if used, draw their power from a supply independent of the input circuit.

Figure 2.7 shows typical connections to actuators when the output is monitored by the tieback input. Note that when a tieback input is not used to monitor a voltage output, the jumper to the TIEBACK INPUT terminal is not connected. When the tieback input is not used to monitor a current output, the return from the actuator is connected to MODULE COMMON, not to the TIEBACK INPUT terminal. The module monitors tieback inputs only when you enable manual mode of the manual control station described below.

Figure 2.8 shows the connections from the PID module to a manual control station required for switching control automatically to the station or manually at the station. The wiring is the same for PID module outputs configured in current or voltage mode.

The MANUAL REQUEST terminal permits the PID module, upon detecting a hard fault or when under PC processor control, to switch the manual control station from automatic to manual mode. The MANUAL MODE terminal is used to inform the PID module when the station is in manual mode. The TIEBACK INPUT terminal monitors the station output and allows a bumpless transfer of control from the manual control station to the PID module.

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Figure 2.4 Terminal

Terminal Identification

Terminal Function

7 6

2 1

18 Input 1 (+ Lead) 17 Input 1 (- Lead) 16 Input 2 (+ Lead) 15 Input 2 (- Lead) 14 Tieback Input 1 13 Tieback Input 2 12 Analog Output 1 11 Module Common 10 Analog Output 2

9 +15V DC 8 15V DC Common 7 -15V DC 6 Manual Mode 1 5 Manual Mode 2 4 Manual Request 3OPT.+5VDCCommon 2 Optional +5V DC 1 Not Used

The tieback inputs can be used to track manual control station output to provide bumpless transfer, or can be used as feedforward inputs.

Module common signal level can be selected to either 15V DC COMMON (system common) for standard compliance, or -15V DC for additional compliance depending on the application.

When the manual control station is in manual, the station switches these line to the MODULE COMMON terminal.

When a request for manual is made from the PID module or when this relay contact output is used for alarm annunciation, the line is switched to the module common signal level for 50 msec. For hardware failure or loss of analog power ( 15V DC), this relay output is held at module common until the fault is corrected.

Programming plugs must be positioned for optional + 5V DC supply.

Identification and Connections

Cat. No. 1771-PDC

Process Variable 1

Process Variable 2

Process Variable 2Process Variable 2

Tieback Input 1 Tieback Input 2

Control Element 1 Module Common Control Element 2

Required +15V DC Power Supply (cat. no. 1770-P1, 1778-P2, or equivalent)

Optional +5V DC Power Supply

(cat. no. 1771-P2 or equivalent)

11097

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Chapter 2

Assembly and Installation

PID Module

TERMINAL IDENTIFICATION

CAT. NO. 1771-PDC

TERMINAL FUNCTION

INPUT 1 (+LEAD)

INPUT 1 (-LEAD)

INPUT 2 (+LEAD)

INPUT 2 (-LEAD)

TIEBACK INPUT 1

TIEBACK INPUT 2

ANALOG OUTPUT 1

MODULE COMMON

ANALOG OUTPUT 2

+ 15V DC +

15V DC COMMON

- 15V DC

MANUAL MODE 1

MANUAL MODE 2

MANUAL REQUEST

OPT. +5V DC COMMON

OPTIONAL +5V DC

NOT USED

Figure 2.5

ypical Connections for 1Loop Control

Power Supply

Belden 8761

General

Manual Control

Station

Two-Wire Transmitter

+4 to 20mA

PV Input

Control Signal Input

Control Signal Output

Actuator +4 to 20mA

Auto/ Manual Switch

214

Manual Request Input

11098

Figure 2.6 Connections to Input Devices

Chapter 2

Aseembly and Installation

PID Module

TERMINAL IDENTIFICATION

CAT. NO. 1771-PDC

TERMINAL FUNCTION

INPUT 1 (+LEAD)

INPUT 1 (-LEAD)

INPUT 2 (+LEAD)

INPUT 2 (-LEAD)

TIEBACK INPUT 1

TIEBACK INPUT 2

ANALOG OUTPUT 1

MODULE COMMON

ANALOG OUTPUT 2

+ 15V DC

15V DC COMMON

- 15V DC

MANUAL MODE 1

MANUAL MODE 2

MANUAL REQUEST

OPT. +5V DC COMMON

OPTIONAL +5V DC

NOT USED

POWER SUPPLY

If used connect a recorder or other monitoring instrument in series with

the transmitter on the transmitter return lead.

(+)

(-)

(+) (-)

2-Wire Transmitter +4 to 20mA

4-Wire Transmitter +1 to 5V DC

11102

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Chapter 2

Assembly and Installation

PID Module

TERMINAL IDENTIFICATION

CAT. NO. 1771-PDC

TERMINAL FUNCTION

INPUT 1 (+LEAD)

INPUT 1 (-LEAD)

INPUT 2 (+LEAD)

INPUT 2 (-LEAD)

TIEBACK INPUT 1

TIEBACK INPUT 2

ANALOG OUTPUT 1

MODULE COMMON

ANALOG OUTPUT 2

+ 15V DC

15V DC COMMON

- 15V DC

MANUAL MODE 1

MANUAL MODE 2

MANUAL REQUEST

OPT. +5V DC COMMON

OPTIONAL +5V DC

NOT USED

Figure 2.7 Connections

to MODULE COMMON terminal 11.

to Output Actuators

If tieback is not used to monitor a voltage output, do not make this

connection.

if tieback is not used to monitor a current output, connect the return lead

(+)

(-)

(+)

(-)

Actuator +1 to +5V DC

+4 to +20mA Actuator

11103

216

PID Module

TERMINAL IDENTIFICATION

CAT. NO. 1771-PDC

TERMINAL FUNCTION

INPUT 1 (+LEAD)

INPUT 1 (-LEAD)

INPUT 2 (+LEAD)

INPUT 2 (-LEAD)

TIEBACK INPUT 1

TIEBACK INPUT 2

ANALOG OUTPUT 1

MODULE COMMON

ANALOG OUTPUT 2

+ 15V DC

15V DC COMMON

- 15V DC

MANUAL MODE 1

MANUAL MODE 2

MANUAL REQUEST

OPT. +5V DC COMMON

OPTIONAL +5V DC

NOT USED

Figure 2.8

Mode Connections to Manual Control Station

Control

Chapter 2

Aseembly and Installation

General

Manual Control

Station

Auto/Manual

Switch

Manual Request Input

Manual Control Station Interface

11104

The PID module is designed for use with commercially available manual control stations, one per loop. The station is connected between the analog output and the controlled element of the process. The station provides manual override control and automatic backup to the PID module. Manual control stations can be used for start-ups, on-line process adjustments, and routine maintenance. The station can be used in either of two ways, manual override control or module back-up.

Manual Override Control

An operator can override automatic control by switching to manual control and adjusting the output at the manual control station. When the manual control station is switched to manual mode, a connection is closed between the MANUAL MODE terminal (referenced to +15V dc) and the MODULE COMMON terminal on the PID module (Figure 2.8). This

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