Rockwell Automation 1771-PD User Manual

Download

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specifications

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

217. . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . .

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Equipment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . .

51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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.

29

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.

210

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

211

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.

212

Chapter 2

Aseembly and Installation

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

213

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

215

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

217

Chapter 2

Assembly and Installation

allows the PID output to be switched open at the manual control station and a manually controlled output to be switched into the system.

When in manual mode, care should be taken not to return to automatic control when the output is below +1V dc or +4mA. If attempted, an output surge could occur. The PID module performs a bumpless transfer when the tieback input is tracking a signal at or above the minimum level of +1V dc or +4mA. Also, the PID module’s operating mode must include integral control and the manual mode status line must be closed at the manual control station. The module monitors tieback inputs only when you enable manual control.

Module Backup

The manual control station can be used to automatically backup the PID module in the event of module failure. A module failure would de-energize the PID module’s contact output and generate a manual request to the manual control station causing control to be transferred in the following manner.

The contact output (Figure 2.9) is a normally closed contact. When the PID module is in normal operation, the contact will be held open. A manual request is generated by contact closure. The contact will close and remain closed in the event of module failure or loss of +

15V dc analog power. Contact closure internally switches the signal at terminal 4 MANUAL REQUEST to terminal 11 MODULE COMMON. There is only one contact output. If two manual control stations are used, both will be switched simultaneously.

If a manual request is generated by program logic, contact closure is a one-shot 50 millesecond closure. The closure can be used to activate an alarm device by connecting a latching relay to terminal 4 MANUAL REQUEST and terminal 11 MODULE COMMON on the PID module.

Once the PID module relinquishes control to the manual control station, the plant operator must physically reset the operation to automatic mode using a switch on the manual control station.

When control is returned from manual to automatic at the manual control station, the PID module performs a bumpless transfer if the tieback analog input is used to track the output from the manual control station and the PID module’s operating mode includes integral control.

218

Figure 2.9

Connections to the Field Wiring Arm

Internal

Chapter 2

Aseembly and Installation

1771 - PID Module

Ω

250

E11 E12

Standard

Compliance

Additional

250

Internal Connections

Input 1 (+ Lead)

Input 2 (+ Lead)

Tieback Input 1

Tieback Input 2

Ω

Analog Output 1

Module Common

Analog Output 2

+15V DC

-15V DC

15V DC Common

1771 - WF

Wiring Arm

External Connections

9 8

2 1

Station 1

Station 2

Manual Request Station 1

Manual Request Station 2

Contact Output (normally closed)

E22 E21

30V peak 1/4 AMP Max. Max. 3VA

OptoIso

NOTE: Optional +5V DC power supply wiring is not shown.

Standard compliance selects module common as 15V DC Common (500 max for current outputs.)

Additional compliance selects module common as -15V DC Common (1250 max for current outputs.)

Programming plugs inserted for current mode.

Programming pl ugs inserted for standard compliance.

Input Power Supply Requirements

The source of power for the input loop when the input is configured for current mode can be either the analog + supply. The choice depends on the selected output compliance and the number of devices in the loop.

Manual Mode 1

Manual Mode 2

Manual Request

Ω

11105

15V dc supply or a separate

219

Chapter 2

Assembly and Installation

+15V dc Analog Supply

When both the module outputs and tieback inputs (if used) are configured in current mode, additional compliance can be selected. As such, module common is internally connected to -15V dc. The +

15V dc analog power supply can provide a 30 V dc source to the input current loop by jumpering the +15V Dc terminal of the PID module to the positive lead of the current transmitter (Figure 2.10). The potential of 30 V dc is enough to provide the required voltage drops for the transmitter, PID module, and manual control station.

220

Figure 2.10

Mode Input Using External +

Current

Chapter 2

Aseembly and Installation

15V dc Supply

PID Module

1771-PD

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

Two-Wire Transmitter +4 to +20mA

(+)

(-)

General

Manual Control

Station

PV Input

Recorder or indicating instrument if used

10997

Separate Supply

If additional compliance is not selected (as when one of the module outputs is configured in voltage mode), a separate DC power supply must be used to power the input current loop.

Power Supply Voltage

When selecting the power supply to operate the input current loop, the required voltage must be equal to the voltage drop across all impedances at the maximum current of 20mA. Current transmitters typically require a voltage drop of 18V dc or more. The process variable input impedance of the PID module (250 ohms), manual control station (100 ohms), recording

221

Chapter 2

Assembly and Installation

or indicating instrument if used (typically 250 ohms) must be considered when calculating the voltage drop in the loop.

For example, the required voltage for an input loop that contained the PID module, manual control station, and current transmitter that requires at least 18V dc would be 18V +2 (250 ohms) (.020 amps)= 18V +10V = 28V dc. Up to 2 V dc could be allowed for voltage drops in the cables when using a 30 V dc source such as the +

15V dc analog power supply with the module output configured for current operation and additional compliance.

If the input loop were to contain a chart recorder and an indicating instrument (250 ohms each) in addition to the basic loop in the previous example, the power supply would have to provide a least 38V dc plus an amount equal to the voltage drop of the cables. A separate power supply would have to be used.

Installation Practices

Power Supply Current

The +

15V dc analog power supply must provide 100mA to the PID module’s analog circuits. This includes 20mA that the module provides to each output current loop. If the +

15V dc supply is providing 20mA to each input current loop, a 2-loop control system will require 140mA. This is within the specification for the Allen-Bradley 1770-P1 power supply rated at 150mA at +

15V dc.

To minimize the effects of electromagnetic interference (EMI), group analog modules together in the I/O chassis whenever possible. Avoid placing PID modules close to AC modules or high voltage DC modules.

It is important to use shielded cable when wiring analog signals. Belden 8761 or equivalent cable has an insulated twisted pair of conductors covered by a foil shield. To reduce the effect of EMI induced noise along the cable, the shield must be properly grounded at one end, only. The recommended grounding point for each cable is identified in the wiring diagram (Figure 2.5-Figure 2.8 and Figure 2.10). One end of the shield should be cut short and taped to insulate it from any electrical contact. The other end should be tied to a common point at earth ground.

222

Optional Instrument Grounding Bus

An alternate grounding system can be used to separate analog signal ground from the grounding of equipment such as motor starters and are

Chapter 2

Aseembly and Installation

welders which generate high electrical noise. Equipment grounding can carry electrical noise when ground loops exists.

The alternate grounding method is for instruments, only. A instrument ground bus is located inside the enclosure containing the I/O chassis, manual control station, and PC processor. The instrument bus is electrically isolated from the I/O chassis and enclosure. The bus is connected to earth ground by a direct path, independent of other equipment ground connections.

When using instrument grounding, the only change to the connection drawings (Figure 2.5 through Figure 2.8 and Figure 2.10) is that the chassis ground symbol would be redefined as instrument ground. All cable shields and the +

15V dc COMMON terminal of the PID module

would be connected to the instrument ground bus.

Chassis Considerations

When multiple PID modules are placed in the same chassis, the +

15V dc commons and +5V dc commons, if used, should be connected to the ground bus at one point. Do not daisy-chain the commons.

The PID dual-slot module must be placed with single module group when placed in a I/O chassis. Up to eight PID modules can be placed in a single 128 I/O chassis. Up to four of the PID modules can be powered from the +5V I/O chassis power supply. The remaining PID modules, if installed, must be powered by a separate +5V dc supply through the field wiring arm +5V dc and 5V dc COMMON terminals. Be sure that the total current requirement for all modules in the I/O chassis using the I/Ochassis power supply does not exceed the rating of the I/O chassis and the I/O chassis power supply.

Avoid placing the PID module close to AC I/O modules or high voltage DC I/O modules. It cannot be inserted in the left-most slot reserved for the processor module in a single I/O chassis system or for the I/O adapter module in a multi-chassis system.

Set switch 1 of the I/O chassis last state switch assembly to the off position to allow PID module operation in soft fault mode. Refer to section titled Loop Control Word B for additional information on soft fault mode selection.

Other intelligent I/O modules can operate without interference in the same I/O chassis with PID modules.

223

Chapter 2

Assembly and Installation

Internal Fusing

The PID module has internal pico fuses to protect circuitry from surges in the optional +5V dc supply., A blown fuse condition is indicated when none of the front panel LED indicators turn on after you turn on this supply. If the LEDs do not turn on, check programming plugs E23 and E24. These plugs allow you to select the source of +5V dc from the backplane or from an external supply. Incorrect positioning of these plugs can prevent the LEDs from turning on even when pico fuses are OK. Check that E23 and E24 are in the correct position for using the external +5V dc supply (Table 2.D and Figure 2.3).

If the fuses are blown, we recommend that you return the module for factory repair through your nearest field service or sales office. Unauthorized repair of these fuses could result in damage to other circuit components and void your warrantee.

Precautions

Take the following precautions to avoid blowing these fuses:

Be sure that the optional +5V dc supply is connected correctly to field

wiring arm terminals (Figure 2.4).

Be sure that the optional +5V dc supply meets specifications

(Table 2.G), especially for surge voltage at turn on.

Supply +5V dc to each PID module using one or more optional external

power supplies.

Place an on/off switch in the +5V dc lead to each PID module. This

allows you to remove power and replace a PID module without turning off power to other PID modules in the chassis.

Remove power from the PID Module’s field wiring arm before

connecting or disconnecting the arm.

Recommendations for Installing or Removing Modules

224

We make the following recommendations for removing one of several PID modules from an I/O chassis.

WARNING: Remove power from a field wiring arm before connecting or disconnecting it. Turn off power to the I/O chassis before inserting or removing any of its modules. Failure to observe this warning can result in damage to module circuitry and/or unpredictable operation of other modules in the chassis with possible damage to equipment and/or injury to personnel.

Chapter 2

Aseembly and Installation

Place PID modules in one or more chassis containing only PID

modules.

Supply +5V dc to each PIC module using one or more optional external

power supplies.

Place an on/off switch in the +5V dc lead to each PID module. This

allows you to remove power and replace a PID module without turning off power to other PID modules in the chassis.

Removal of a Faulted PID Module

You can replace a faulted PID module in an I/O chassis using the following procedure if each PID module is supplied with +5V dc from a separate power supply or from a common supply with a switch in each +5V dc lead.

1. Select the soft fault mode that allows PID modules to continue

operation when they lose communication with the PC processor. Do this by means of your ladder program.

2. Turn off power to the I/O chassis. Block transfers cease but PID

modules continue to operate.

3. Turn off the +5V and +

15V dc power to the faulted module.

4. Replace the faulted PID module.

5. Turn on power to the module and I/O chassis.

6. Restore the original soft fault mode to the PID modules.

If there are other modules and/or other PID modules without an external +5V dc supply, they cease to operate when you turn off power to the chassis. After restoring power, you must download PID control parameters to PID modules through a load/enter sequence.

Keying

PID modules (rev C or later) have the option for you to select how outputs respond when +5V dc is removed from the module. You select either maximum or minimum, output using programming plus (refer to titled Programming Plug Selection).

The backplane connector should be keyed to accept only this module after its position in the I/O chassis has been determined.

225

Chapter 2

Assembly and Installation

Plastic keying bands shipped with the I/O chassis should be used. The position of the keying bands on the upper backplane connector must correspond to the mating slots on the module connector.

Refer to Figure 2.11. Using needle-nose pliers, place the keying bands on the backplane connector between these numbers:

Slot 0 (left) 8 and 10 18 and 20

slot 1 (right) 2 and 4 28 and 30

The position of the keying bands can be changed if subsequent system design requires the module to be moved to a different location.

226

Figure 2.11

Diagram

Keying

Chapter 2

Aseembly and Installation

Single Module Group

0PID Module 1

Upper Backplane Connectors

Power Supply Specifications

Keying

Bands

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Left Connector

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Right Connector

11106

Isolation must be maintained between the analog and digital circuits of the PID module to minimize electrical noise interference. Therefore, separate power supplies must be used for the analog +

15V dc supply and for the

digital +5V dc supply.

The requirements for the customer +

15V dc power supply and for the optional +5V dc power supply are listed in Table 2.E and Table 2.F, respectively.

227

Chapter 2

Assembly and Installation

Table 2.E Customer

Output Current

Output V

Regulation (type)

Line Regulation (for 10V AC input change)

Load Regulation (no load to full load)

Ripple 10mVpp 10mVpp

Overvoltage Protection

Current Limit (percent of full load)

[1] The module is not protected from overvoltages from the customer power supply

Table 2.F +5V dc Power Supply (Optional) Requirements

15V dc Power Supply Requirements

Specifications

oltage T

olerance 1% 1%

[1]

+15 V

100mA 100mA

Series Series

+0.2% +0.2%

+1.0% +1.0%

+18V dc 18V dc

125% 125%

olts

15 V

olts

Specifications +5Volts

oltage (at wiring arm)

Current

oltage Regulation

Rise T

ime (to 4.75V dc) Less than 10msec

5.05V dc

1.2A per PID module

Sum of all deviations due to line, load, and ripple should not exceed +

0.15V dc

228

Chapter 2

Aseembly and Installation

Module Specifications

Process

Number 12binary

Configuration

Range (userselectable)

Digital Resolution

ariable Inputs

process variable input 1

process variable input 2

Differential

+4 to +20mA

+1 to +5V dc

12bit binary

, 1 part in 4095

The PID module specifications are listed in Table 2.G.

Table 2.G Specifications

Digital Resolution Maximum Current

Accuracy

0.1% of range at 250C3VA

Input Impedance

250 ohms (current)

4.7 megohms (voltage)

Maximum Allowable Input

30mA (current)

25V rms (voltage) Backplane or External (Digital Circuits)

emperature Coefficient

, 1 part in 4095

250mA

Maximum Power

Digital Inputs (from manual

manual control station)

wo independent inputs for moni

toring

Power Requirements

1.2A at +5V dc

Accuracy +

0.1% of range at 250C

Input Impedance

250 ohms (current) analog output 1

10 megohms (voltage)

Common Mode Rejection Ratio

70dB DC

Common Mode V

common

Common Mode Input Resistance referenced to power supply Relative Humidity Rating

2.5 megohms

Input Frequency Respnse

3dB at 1kHz

Maximum Allowable Input

oltage Range

200V with respect to module +4 to +20mA

Number

Configuration

Range (userselectable)

50 ppm/0C

Analog Outputs 100mA A

analog output 2 100msec, typical

Single ended

(With output common internally

common

the output will drive up to a 500 ohm

load over the full current range.

+1 to +5V dc

External (Analog Circuits)

100mA at 15V dc

Loop Update T

Ambient T

Operation 00C to 600C (320F to

1400F

Storage 400C to 850C (400F to

1850F)

5% to 95% (without condensation)

Electrical Isolation

[1]

1500V rms (transient

(Isolation is achieved by

T +15V dc

ime

emperature Ratings

30mA (current)

(500 ohms minimum load resistance

optoelectronic coupling between I/O

229

Chapter 2

Assembly and Installation

dc (voltage) 10mA maximum load current.)

125V

emperature Coeffeicient

50 ppm/0C

ieback Inputs

Number +

tieback input 1

tieback input 2

Configuration

Single ended

Range (userselectable)

+4 to +20mA

+1 to +5V dc

Digital Resolution

Accuracy

emperature Coefficient

Number

Peak V

oltage

analog circuit and control logic)

Keying

12bit binary

0.1% of range at 250C

50 ppm/0C

one normally closed contact,held extended from 500ohms (standard compli

open

30V

, 1 part in 4095

Contact Output

Left connector (slot 0) between 8

and 10, 18 and 20

Right connector (slot 1) between 2

and 4, 28 and 30

[1]

If all analog outputs and tieback inputs

used are selected to current mode, the

compliance of the analog outpus can be

ance to 1250 ohms(additional compliance).

This is achieved by internally referencing the

outputs to 15V dc.

230

Programming

Chapter

General

Before starting to program the PID module, read this entire chapter thoroughly. Be sure that the programming plug functions have been selected as described in section titled Programming Plug Selection.

The PID module can be programmed in four general steps:

1. Choose the PID module features required for the application. These

are listed in section titled Capabilities (chapter 1) and are presented in the algorithm flow chart (Figure 3.15).

2. Identify the control bits and loop storage words which must be

programmed to implement the features. These are defined in section titled Word and Bit Definitions. Record the values of the storage words and the logic state of the control bits on the worksheets found in appendix A.

3. Write the ladder diagram program and assign data table addresses to

the data blocks used to store loop values. The examples presented in appendix B or C should be used as guides.

4. Using a industrial terminal, enter the program into memory and the

block data into the data table. Refer to the worksheets on which the values of the loop storage words have been recorded. Set the appropriate control bits.

Sections listed below provide information for selecting PID module features and programming the module.

Section titled Operational Overview provides an overview of the

programming concepts which are used to program and monitor the PID module.

Section titled Word and Bit Definitions defines the words and bits

which can be used to program the module.

Section titled Algorithm Flow Chart contains the algorithm flow chart

and explains it use.

Section titled Block Transfer Programming explains how the module is

programmed using block transfer instructions.

31

Chapter 3

Programming

Section titled Programming Consideration explains the application of

block transfer instructions.

Section titled Expanded Features describes the expanded features of the

PID module and how they can be applied.

Additionally, four appendices contain helpful programming information:

Appendix A contains the worksheets which are used to record data that

is entered into the PC processor and transferred to the PID module.

Appendix B describes a program that performs continuous block

transfers to the PID module. This program may be used when continuous parameter adjustment or continuous reporting of module status is required for a critical application.

Appendix C describes a program that performs periodic block transfers

to the PID module. This program may be used when less frequent parameter adjustment is required.

Appendix D contains summary word and bit tables and a word/bit

reference.

Operational Overview

The PID module is a closed loop process controller with proportional, integral, and derivative control action. Control algorithm features are user determined and loaded in the PID module by block transfer from the PC processor. The PID module is equipped to control up to two process control loops using its internal microprocessor. Because the features of the two loops are similar, the description will be general to both loops except where otherwise stated. Each loop is individually configured with its own parameter values.

PID Algorithm

The PID module contains features which are user-selected to perform the desired control. Figure 3.1 is a simplified diagram of the PID module features. Basically, the PID module reads the process variable, compares it to the set point, and adjusts the analog output to make the process variable equal the set point. The process variable PV is the analog input from the process. The setpoint SP is the equilibrium value of the process, and the analog output is the control variable to the process. The difference between the set point and the process variable is the error signal, E=SP-PV.

32

The PID module can perform a combination of proportional, integral and derivative control. Integral control is also known as reset action. Derivative control is also known as rate action. The PID module can perform relatively simple or very complex control based on selected

Chapter 3

Programming

features. The full algorithm flow chart is presented in section titled Algorithm Flow Chart.

The PID module (rev C or later) uses the ISA algorithm (P, I and D dependent gains) or the Allen-Bradley algorithm (P, I and D independent gains). Refer to appendix E for algorithm comparison and selection. Earlier revision modules use only the Allen-Bradley algorithm.

Figure 3.1 Simplified

PID Algorithm

Feedforward Input

Process Variable

A/D

Hardware

Analog

Input

Digital

Filter

Error=SPPV

Lead Lag

BIAS

PID

(FFV) Control Variable

D/A

Hardware

Analog Output

11093

Block Transfer Data Blocks

Data block files are areas of the PC processor data table used to store loop control words and loop values. The features of the module are selected by setting word and bit values in data block files. The data block files are transferred to the PID module by block transfer instructions.

Three write block transfers are required to load the PID module with data from three data table block files. The dynamic block DB contains values which are subject to change for both loops. The loop 1 block LP1 and loop 2 block LP2 contain loop constants which seldom change.

33

Chapter 3

Programming

The status block SB is a read block transfer file used to report the current status of the PID module and any alarm condition detected by the module. The transfer of the status block is also used to prompt the next write block transfer.

Figure 3.2 illustrates the multiple block concept.

Figure 3.2 Multiple

Block Concept

PCProcessor DataTable

Dynamic Block

Loop1 Constants Block

Loop2 Constants Block

Status Block

PIDModule

WriteBlock Transfer

ReadBlock Transfer

11094

34

PC Processor Memory Requirements

The PID module requires multiple files in the C processor data table to store the different blocks of data. Storage requirements are determined by the features selected. The module can be configured for one or two loops with either standard or expanded features. There are four different memory requirements for storing block of data (Figure 3.3).

User program memory requirements will vary depending on the application. Examples are shown in appendicies B and C.

Chapter 3

Programming

Figure 3.3

File Memory Requirements

Block

1 Standard Loop 1 Expanded Loop 2 Standard Loops 2 Expanded Loops

Dynamic Block 10 Words

Loop 1 Constants Block 12 Words

Status Block 11 Words

Dynamic Block 10 Words

Loop 1 Constants Block 19 Words

Status Block 11 Words

Dynamic Block 17 Words

Loop 1 Constants Block 12 Words

Loop 2 Constants Block 12 Words

Status Block 18 Words

Dynamic Block 17 Words

Loop 1 Constants Block 19 Words

Loop 2 Constants Block 19 Words

Status Block 18 Words

Load/Enter Sequence

The load/enter sequence is used when all PID control parameters (dynamic block and loop block data) are transferred from the PC processor to the PID module. The load/enter sequence is required at power-up and whenever it is necessary to change any of the loop constants in LP1 or LP2 or selected control bits in the master control word. (After a load/enter sequence has been completed, dynamic block data can be changed at any time by a write block transfer). Changes to loop constants require a load/enter sequence as a safety consideration to prevent inadvertent changes which could adversely affect the system.

11095

35

Chapter 3

Programming

The PID module prompts the sequencing of block transfers. The write block transfer instruction in the user program contains the data table address of the first word of the block file to be transferred. By manipulating this address, different data block files can be transferred with the same write block transfer instruction.

There are three control bits which are associated with the handshaking of the load/enter sequence.

The load bit is set in the dynamic block to allow the PID module to

accept dynamic block data and to load loop 1 and loop 2 constants into the module’s buffer.

The ready bit is returned in the status block to indicate that the write

block transfers were acceptable and that the module is able to process the information.

The enter bit is set to activate the information in the module’s buffer

and to start control based on the new parameters transferred during the load/enter sequence.

An overview of the load/enter sequence is presented in Figure 3.4. Additional information can be found in sections titled Power-up Load/Enter Sequence and Load/Enter Sequence.

36

Chapter 3

Programming

Command

Load Bit

Enter Bit

Status

Ready Bit

P R O C E S S O R

Figure 3.4 Load/Enter

Sequence

Block Transfers read write

1st

2nd

3rd

4th

LP1

5th

6th LP2

Description

1st The processor reads the status block to start

the sequence.

2nd

The processor writes the dynamic block to the PID module (load bit set) to transfer dynamic block data.

3rd The processor reads the status block to confirm

dynamic block data and to address the next block transfer.

4th The processor writes loop constants to the module

I D

M O D U L E

to set the features for loop 1.

5th The processor reads the status block to confirm

loop 1 constants andd to address the next block transfer.

6th

The processor writes loop constants to the module to set the features for loop 2.

SB = Status Block, DB = Dynamic Block, LP1 and LP2 = Loop 1 and Loop 2 Parameter Blocks

7th

8th

9th

7th The processor reads the status block to confirm the

data for the entire sequence (readdy bit set) and to address the next block transfer.

8th The processor writes the dynamic block to the

module to start PID control (enter bit set).

9th

The processor reads the status block to confirm that the module has been programmed and no errors were detected.

Toggle sequence or periodic block transfers.

11107

37

Chapter 3

Programming

Word and Bit Definitions

This section defines the words and bits of the three write blocks and the single read block. For ease of reference, the following word and bit notation is used throughout the manual:

A PID module word is abbreviated as Wxx. Example: Word number 12 = W12.

A PID module bit is abbreviated as Bxx. Example: Bit number 07 = B07.

The word and bit abbreviations can be used together. Example: Word number 12, Bit number 07 = W12 B07.

Other notations which will be used are (LE) and (XF). The symbol (LE) is used to designate the four bits in the master control word which require a load/enter sequence to occur before the PID module will accept a change to them. The symbol (XF) is used to designate words or bits which are used to select the Expanded Features of a loop.

For ease of reference, the parameter words required to program the module are numbered consecutively in the following sections.

38

Section titled Dynamic Block: Words W01-W17.

Section titled Loop Constants Block: W18-W36 for loop 1, W38-W56 for loop 2.

Section titled Status Block: W57-W74.

Dynamic Block: Words W01W17

The dynamic block is a write block transfer file of up to 17 words. It is used to establish the features of the PID module, to program the most frequently changing (dynamic) parameters of loop 1 and loop 2, and to load information required by the PID module for controlling the block transfer sequences.

If loop 1 is selected, only words W01 must be programmed. If both loops are selected, then the entire 17 word block must be programmed.

The 17 words of the dynamic block are defined in the paragraphs that follow. Table 3.A lists the dynamic block words. All the words of the

Chapter 3

Programming

dynamic block, loop blocks and status block are listed in Table 3.J, Figure 3.13 and Figure 3.14 found at the end of section title Word and Bit Definitions.

Table 3.A Dynamic

Block W

ords

W01 W02 W03 W04 W05 W06 W07 W08 W09 W10 W11 W12 W13 W14 W15 W16 W17

Word

Master Control W Control W Dynamic Block Start Address Loop 1 Block Start Address Set Analog Output 1 Set Point 1 Proportional Gain 1 Bias 1

Set Process Variable 1 Set Feedforward Input 1

Loop 2 Block Start Address Set Analog Output 2 Set Point 2 Proportional Gain 2 Bias 2

Set Process Variable 2 Set Feedforward Input 2

ord

Title Abbreviation

ord

SET OUT 1

SP1

BIAS 1

SET PV1

SET FFI1

SET OUT 2

SP2

BIAS 2

SET PV2

SET FFI2

W01 Master Control Word. This word initiates all activities in the PID module from power-up. This word programs the module configuration, controls the initiation of the block transfer sequences, and can control the setting of the analog outputs and the contact output. Bits 17 through 00 are defined below and summarized in Figure 3.5.

W01 B17, B16 Block Identifiers. Both bits must be set to 1 to identify this block as the dynamic block.

W01 B15 Loop Select. [LE] Reset to 0 selects both loop 1 and loop

2. Set to 1 selects loop 1 only. When loop 1 and loop 2 are selected, all words in the dynamic block are used and both loop blocks must be programmed. When loop 1 is selected, only words W01 through W10 of the dynamic block are used and the loop 1 block must be programmed.

W01 B14 Standard/Expanded Features. [XF], [LE] Reset to 0 selects standard loop features. When the stand loop is selected, loop 1 words W30 through W36 and loop 2 words W50 through W56 are NOT used by the module. Set to 1 selects expanded loop features

39

Chapter 3

Programming

such as feedforward, scaling, lead/lag, and all the words in the loop block must have a value. The value of unused expanded feature words must be zero.

W01 B13 Calibration. Reset to 0 selects normal operation. Set to 1 only for calibrating the module. This bit is examined only at power-up, and is used with W02 B17 and B16.

310

Figure 3.5

Control W

Master

Chapter 3

Programming

ord W01

W01 B17 Must be set to 1

W01 B16 Must be set to 1

W01

W01 B15 1=Loop 1 only

0=Both Loop 1 and Loop 2

W01 B14 1=Expanded loop features

0=Standard loop features

W01 B13 1=Calibration

0=Normal Operation

W01 B12 1=Binary format for words W05, W09, W10,

W12, W16, W17, W63, W64, W66, W70, W71, and W73 0=BCD format

W01 B11 1=Binary format for the set point W06 (W13)

0=BCD

W01 B10 1=Soft Fault Reset

0=Remain in Soft Fault

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

BCD

SOFT FAULT RESET

EXPANDED

LOOP 1

2 LOOPS

STANDARD

CALIB BINARY

BCD

BINARY

DIAG

LOOP TIME

LOAD

VERIFY

CODE

ENTER

SET

OUTPUT 2

W01 B07 1=Report diagnostics in W60 0=Report loop time in W60

SET

OUTPUT 1

MANUAL

REQUEST

W01 B06 1=Initiates load/enter sequence 0=Sequence not initiated

W01 B05 Must be set to 0

W01 B04 Must be set to 0

W01 B03 1=Completes the load/enter sequence 0=Loop constants remain in buffer

W01 B02 1=Set Analog Output 2 (W12) 0=Use algorithm output

W01 B01 1=Set Analog Output 1 (W05) 0=Use algorithm output

W01 B00 1=Contact closure oneshot

0=Off; resets oneshot

11108

311

Chapter 3

Programming

W01 B12 Binary/BCD Format. [LE] Reset to 0 selects the 4-digit BCD (4095 maximum) format. Set to 1 selects the 12-bit are listed in Table 3.B.

Table 3.B Binary/BCD

Format W

ords

Word

W05 W09 W10 W12 W16 W17

Set Analog Output 1 Set Process V Set Feedforward Input 1 Set Analog Output 2 Set Process V Set Feedforward Input 2

Title Word Title

ariable 1

ariable 2

W63 W64 W66 W70 W71 W73

Read Loop 1 Output Read Analog Input 1 Read T

ieback Input 1 Read Loop 2 Output Read Analog Input 2 Read T

ieback Input 2

W01 B11 Set Point Format. [LE] Reset to 0 selects 4-digit BCD (4095 maximum) format for set point 1 in word W06 and set point 2 in word W13. Set to 1 selects the 12-bit binary (4095 maximum) format. If scaling has been selected by B16 = 1 in word W30 for loop 1 or in W50 for loop 2, the 4-digit BCD value has the data format of 9999.

W01 B10 Soft Fault Reset. Reset to zero holds the module in soft fault mode until this bit is set to 1. Set to 1 allows recovery from the soft fault mode after the fault is corrected. Soft fault mode is signified by W58 B10 = 1 and is indicated by the flashing STAND-ALONE yellow LED on the PID module. The soft fault mode of operation is selected by bits B15, B14, B13 in word W19 for loop 1 and W39 for loop 2.

312

W01 B07 Loop Time/Diagnostic. Reset to 0, causes word W60 to report loop update time. Set to 1 causes word W60 to report error codes. The upper byte of word W 60 reports dynamic block error codes. The lower byte reports error codes and loop 1 and loop 2 blocks.

W01 B06 Load. Reset to 0 inhibits the load/enter sequence. Set to 1 initiates the load/enter sequence.

When the load bit is set, the loop constants are loaded into the module’s buffer. They are not used until the enter bit is set at the completion of a load/enter sequence. The same applies to the four bits in the master control word W01 B15, B14, B12, B11 designed

Chapter 3

Programming

by (LE). These bits are protected from accidental change because they control the number of PID loops, standard or expanded loop features and binary or BCD data format. These bits can be changed in the same manner that loop constants are changed, only by a load/enter sequence. The remaining bits in the master control word and the remaining dynamic block words can be changed at any time by a write block transfer. See sections titled Power-Up Load/Enter Sequence and Load/Enter Sequences.

W01 B05, B04 Verify. Both bits must be set to 0 for normal operation.

W01 B03 Enter. Used with load bit W01 B06 to complete a load/enter sequence. when 0, the data previously loaded remains in the module’s buffer. Set to 1 the buffered data is moved from the buffer into the module’s active area and the sequence is completed. The buffered data includes all loop constants and the four (LE) bits in the master control word W01 B15, B14, B12, B11. See sections titled Power-Up Load/Enter Sequence and Load/Enter Sequence.

W01 B02 Set Output 2. Reset to 0 selects the analog output value determined by the module’s PID algorithm. Set to 1 selects the analog output as the value stored in word W12, Set OUT2, downloaded from the PC processor. When reset to 0, the analog output value is adjusted automatically from the SET Out value to the value determined by the PID algorithm, a bumpless transfer.

W01 B01 Set Output 1. Reset to 0 selects the analog output value as determined by the module’s PID algorithm. Set to 1 selects the analog output as the value stored in word W05, SET OUT1, downloaded from the PC processor. When reset to 0, the analog output value is adjusted automatically from the SET OUT value to the value determined by the PID algorithm, a bumpless transfer.

W01 B00 Set Manual Request. Reset to 0 the PID module inhibits contact closure. Set to 1 generates a contact closure for 50msec. To repeat this one-shot closure, it is necessary to first reset this bit to 0 and then set it to 1 again.

W02 Control Word. Use this word to select ISA or A-B values for the PID algorithm, or to select module calibration.

W02 B17, B16 Calibration. Refer to chapter 5.

313

Chapter 3

Programming

W02 B00 PID Algorithm. Reset to 0 the PID module uses A-B gain values. Set to 1 the PID module uses ISA values.

W03 Dynamic Block Start Address. This word contains the data table address of the first word in the file associated with the dynamic block. The address is required by the PID module to prompt the transfer of the dynamic block.

W04 Loop 1 Block Start Address. This word contains the data table address of the first word in the file associated with the loop 1 block. The address is required by the PID module to prompt the transfer of loop 1 constants.

W05 Set analog Output 1, SET OUT1. The value stored in this word becomes the analog output when W01 B01 = 1.

Normally, the PID module outputs the PID algorithm value when W01 B-1 = 0. Data format is 4-digit BCD or 12-bit binary. Format is determined by W01 B12. Range is 0000 to 4095.

W06 Set Point 1, SP1. This word contains the set point value for loop 1. Data format is 4-digit BCD or 12 bit binary as selected by W01 B11. The unscaled range is 0000 to 4095.

When set point scaling is selected, the data format should be 4-digit BCD. Scaling can be selected by B16=1 in word W30 when expanded loop features are selected by W01 B14 = 1. The sign bit W19 B07 and the x10 multiplier bit W19 B06 determine the range which can be +

99990.

When scaling is selected, words W31 and W32 must contain the minimum and maximum range values SMIN1 and SMAX1, respectively. Refer to section titled Scaling for additional information about scaling.

W07 Proportional Gain 1, Kp1 (Kc1). This word contains the proportional gain constant for loop 1. The value is the same for A-B (Kp1) or ISA (Kc1), selected by W02 B00. Data format is 4 digit BCD (99.99 dimensionless) with implied decimal point. Multiplier bit W19 B04, B05 can be selected for x1, divided by 10, x10, x100 (Table 3.F, Multiplier Codes). By using multipliers, the range can be extended from

0.000 to 9999.

314

Chapter 3

Programming

W08 Bias 1, BIAS1. When using only standard loop features, the loop bias is the value stored in this word. When expanded loop features are selected by W01 B14 = 1, either the feedforward term FFV or the value stored in this word can be used as the loop bias. The feedforward term is normally used unless W30 B02 = 1 which sets the bias to the value stored in this word.

The data format is 4-digit BCD, range 0000 to 9999. When expanded loop features are selected, the negative bias bit W30 B01 = 1 allows a full-scale range of +

9999.

W09 Set Process Variable 1, SET PV1. The value stored in this word is used by the PID module as the process variable for loop 1 when W18 B15 =1. Normally, the PID module uses the hardware analog input value when W18 B15 = 0. Data format is 4-digit BCD or 12-bit binary. Format is selected by W01 B12. Range is 0000 to 4095.

W10 Set Feedforward Input 1, SET FFI1. (XF) The value stored in this word is used by the PID module as the feedforward input when W30 B13 = 0. The PID module uses the tieback input 1 value as the feedforward input when W30 B13 = 1. This word can be used only when expanded loop features are selected by W01 B14 = 1. Data format is 4-digit BCD or 12-bit binary. Format is selected by W01 B12. The range is 0000 to 4095.

NOTE: The following words are programmed if the module is configured for 2-loop operation, W01 B15 = 0.

W11 Loop 2 Block Start Address. This word contains the data table address of the first word in the file associated with the loop 2 block. The address is required by the PID module to prompt the transfer of the loop 2 constants.

W12 Set Analog Output 2, SET OUT2. The value stored in this word becomes the analog output when W01 B02 = 1. Normally, the PID module outputs the PID algorithm value when W01 B02 = 0. Data format is 4-digit BCD or 12-bit binary. Format is selected by W01 B12. Range is 0000 to 4095.

W13 Set Point 2, SP2. This word contains the set point value for loop 2. Data format is 4-digit BCD or 12-bit binary as selected by W01 B11. The unscaled range is 0000 to 4095.

315

Chapter 3

Programming

When set point scaling is selected, the data format should be 4-digit BCD. Scaling can be selected by B16 = 1 in word W50 when expanded loop features are selected by W01 B14 = 1. The sign bit W39 B07 and the x10 multiplier bit W19 B06 determine the range which can be +

99990.

When scaling is selected, words W51 and W52 must contain the minimum and maximum range values SMIN2 and SMAX2, respectively. Refer to section 3.6.1 for additional information about scaling.

W14 Proportional Gain 2, Kp2 (Kc2). This word contains the proportional gain constant for loop 2. The value is the same for A-B (Kp2) or ISA (Kc2), selected by W02 B00. Data format is 4-digit BCD (99.99 dimensionless) with implied decimal point. Multiplier bits W19 B04, B05 can be selected for X1, divided by 10, x10, x100 (Table 3.F, Multiplier Codes). By using multipliers, the range can be extended from

0.000 to 9999.

W15 Bias 2, BIAS2. When using only standard loop features, the loop bias is the value stored in this word. when expanded loop features are selected by W01 B14 = 1, either the feedforward term FFV or the value stored is this word can be used as the loop bias. The feedforward term is normally used unless W50 B02 = 1 which sets the bias to the value stored in this word.

The data format is 4-digit BCD, range 0000 to 9999. When the expanded loop features are selected, the negative bias bit W50 B01 = 1 allows a full scale range of +

9999.

W16 Set Process Variable 2, SET PV2. The value stored in this word is used by the PID module as the process variable for loop 2 when W38 B15 = 1. Normally, the PID module uses the hardware analog input value when W38 B15 = 0. Data format in 4 digit BCD or 12-bit binary. format is selected by W01 B12. Range is 0000 to 4095.

W17 Set Feedforward Input 2, SET FF12. (XF) The value stored in this word is used by the PID module as the feedforward input when W50 B13 = 1. Normally, the PID module uses the tieback input 2 value as the feedforward input when W50 B13 = 0. This word can be used only when expanded loop features are selected by W01 B14 = 1. Data format is 4-digit BCD or 12-bit binary. Format is selected by W01 B12. The range is 0000 to 4095.

316

Chapter 3

Programming

Loop Constants Block: W18W36 for Loop 1, W38W56 for Loop 2

Loop block are write block transfer files of up to 19 words. They contain loop constants and are used to establish the loop features of the PID module. Loop 1 block must be used when the PID module is controlling only one loop. The loop 1 and loop 2 blocks are used for 2-loop control. Three control words are used to select the features in each loop. They are loop control words A and B, and the expanded loop control word. The remaining words are used to store values which typically remain constant during normal operation.

Loop 1 words W18 through W29 are programmed if standard features are selected by W01 B14 = 0. The entire block (words W18 through W36) is programmed if the expanded loop features are selected by W01 B14 = 1.

When both loops are used, loop 2 words W 38 through W49 must also be programmed for standard features when W01 B14 = 0. The entire loop 2 block (words W38 through W56) must also be programmed if the loop 2 expanded features are selected by W01 B14 = 1.

To change the programming of any word or bit in the loop blocks, a load/enter sequence must be initiated.

The 19 words that comprise the loop block are defined in the paragraphs that follow. Table 3.C lists the loop block words. All the words of the dynamic block, loop blocks and status block are listed in Table 3.J, Figure 3.13 and Figure 3.14 found at the end of section titled Word and Bit Description.

NOTE: Because the loop 1 and loop 2 blocks are very similar, the definitions of the words and bits will be presented once for loop 1. Reference to loop 2 will be indicated by parentheses, i.e. (loop 2).

317

Chapter 3

Programming

Table 3.C

Block W

Loop

ords

Word

Standard Features W18(W38) W19 (W39) W20 (W40) W21 (W41) W22 (W42) W23 (W43) W24 (W44) W25 (W45) W26 (W46) W27 (W47) W28 (W48) W29 (W49)

Expanded Features W30 (W50) W31 (W51) W32 (W52) W33 (W53) W34 (W54) W35 (W55) W36 (W56)

Loop Control W Loop Control W Input Filter Time Constant Maximum Negative Error Maximum Positive Error Dead Band Integral Gain Derivative Gain Integral T Derivative T Minimum Output Limit Maximum Output Limit

Expanded Control W Minimum Scaling V Maximum Scaling V Feedforward Of Feedforward Gain Lead T Lag T

erm Limit

ime Constant

Title Abbreviation

ord A ord B

ord

alue

fset

VDMAX

SMAX

W18 (W38) Loop Control Word A. This word together with loop control word B, W19 (W39), and loop expanded control word, W30 (W50), select the configuration for the loop. Bits 17 through 00 of loop control word A are defined below and summarized in Figure 3.6 for loop 1 word W18 and loop 2 word W38.

T EMN EMP

K MAX

VMIN VMAX

SMIN

FFO

318

W18 (W38) B17, B16 Block Identifiers. These two bits identify this block as the loop block. B17 = 0 and B16 = 1 for loop 1. (For loop 2, B17 = 1, B16 = 0.)

W18 (W38) B15 Source of Process Variable. Reset to 0 selects the analog input as the process variable input for the loop. Set to 1 selects the value SET PV in word W09 (W16) as the process variable for the loop.

W18 (W38) B14 Square Root of Process Variable. Reset to 0 inhibits the square root function. Set to 1 enables the normalized square root of the process variable, (square root of PV x (square root of 4095). Square root allows the linearization of differential pressure type flow transducers.

Chapter 3

Programming

(W38) B13 Error Polarity. Reset to 0 defines the error as SP-PV for direct acting control. Set to 1 defines the error as PV-SP for reverse acting control.

319

Chapter 3

Programming

Figure 3.6

Control

ord A, Loop 1 W18 and Loop 2 W38

W18 B17 Must be set to 0: W38 B17 must be set to 1

W18 B16 Must be set to 1: W38 B16 must be set to 0

W18(W38) B15 1=PV from PC Processor W09(W16)

0=PV from hardware analog input

W18(W36) B14 1=Perform square root of PV

0=No square root

W18(W38) B13 1=Error=(PVSP) reverse acting

0=Error=(SPPV) direct acting

W18(W38) B12 1=Use error limiting W21, W22 (W41, W42)

0=No limiting

W18(W38) B11 1=Use error dead band W23 (W43)

0=No dead band

W18(W38) B10 1=Use integral term limiting W26 (W46)

0=No limiting

Loop 1 W18

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

PV1 PID

PV2 PID

PV1

PV2

PV-SP ERROR1 SP-PV

PV-SP ERROR2 SP-PV

LIMIT ERROR1

LIMIT ERROR2

DEAD BAND

V1 MAX LIMIT

PROPORTIONAL

ERROR

FUNCTION

PROPORTIONAL

ERROR

FUNCTION

INTEGRAL ERROR FUNCTION

DERIV. ERR.

Error

VD MAX

LIMIT

VD MAX

LIMIT

Loop 2 W38

W18(W38) B07,06 Proportional Error Function, E 0 0=Error

0 1=2/3 (Error) + 1/3 (Error) 1 0=1/3 (Error) + 2/3 (Error) 1 1= (Error)

2 2

HOLD PID1

HOLD PID2

HOLD

BIAS1

HOLD

BIAS2

W18(W38) B05,04 Integral Error Function, E 0 0=Error

0 1=2/3 (Error) + 1/3 (Error) 1 0=1/3 (Error) + 2/3 (Error) 1 1= (Error)

W18(W38) B03 Derivative Error, E

1=PV 0=Error

W18(W38) B02 1=Use derivative term limiting W27(W47) 0=No limiting

W18(W38) B01 1=Hold last V 0=Normal V

W18(W38) B00 1=Hold last BIAS value 0=Normal BIAS calculations

Note: If you change a loop 1 or loop 2

parameter, you must initiate a load/enter sequence

320

value

PID

calculations

PID

2 2

11109

Chapter 3

Programming

W18 (W38) B12 Error Limit. Reset to 0 inhibits error limiting. Set to 1 the maximum negative error term for the loop is limited to the value EMN in word W21 (W41). The maximum positive error is limited to value EMP in word W22 (W42).

W18 (W38) B11 Dead Band. Reset to 0 inhibits dead band. Set to 1 enables the dead band feature using the value in word W23 (W43). Refer to word W23 (W43) Dead Band.

W18 (W38) B10 Maximum Integral Term Limit. Reset to 0 inhibits integral term limiting. Set to 1 the value of the integral term V

is limited to the maximum value VI MAX in word W26 (W46).

This limit applies to both the negative and positive excursions of the integral term V I.

W18 (W38) B07, B06 Proportional Term Error. The setting of the 2-bit code determines which error signal will be used for the proportional term V error term E

include straight error and error squared. Note that the

calculation. The choices of the proportional

sign is retained. The error codes are listed in Table 3.D.

W18 (W38) B05, B04 Integral Term Error. The setting of the 2-bit code determines which error signal will be used for the integral term V

calculation. The choices of the integral error term EI include

straight error and error squared. Note that the sign is retained. The error codes are listed in Table 3.D.

W18 (W38) B03 Derivative Term Error. Reset to 0 the error signal is used in the derivative calculation. Set to 1 the process variable signal is used.

321

Chapter 3

Programming

Table 3.D

Function Codes

Error

W18(W38)

B07 B05

0 0 1 1

B06 B04

Error Function

0 1 0 1

Error 2/3 (Error) + 1/3 (Error) 1/3 (Error) + 2/3 (Error)

(Error)

Error|Error|

Where (Error)2=_________

512

2 2

W18 (W38) B02 Maximum Derivative Term Limit. Reset to 0 inhibits derivative term limiting. Set to 1 the value of the derivative term VD is limited to the maximum value VD MAX in word W27 (W47). This limit applies to both negative and positive excursions of the derivative term VD.

W18 (W38) B01 Hold PID Calculation. Reset to 0 continues the PID algorithm calculation. Set to 1 holds the PID algorithm output VPID at its last value. The hold is useful when turning the feedforward portion of the loop.

322

W18 (38) B00 Hold Bias. Reset to 0 continues the bias calculation. Set to 1 holds the bias at its last value. The hold is useful when tuning the PID portion of the loop.

W19 (W39) Loop Control Word B. This word together with loop control word A, W18 (W38), and the loop expanded control word, W30 (W50), select the configuration for the loop. Bits 17 through 00 are defined below and summarized in Figure 3.7 for loop 1 control word B W19, and loop 2 control word B W 39. Note that bits B11, B10, B07, and B06 are valid only if the expanded loop feature has been selected by W01 B14 = 1.

W 19 (W39) B17 VPID +/xBias. Reset to 0 the output is the sum V = VPID + BIAS. Set to the output is the normalized product V = (VPID x BIAS)/4095. The sum is normally used.

W19 (W39) B16 Output Limiting. Reset to 0 inhibits output limiting. Set to 1 the analog output value is limited to the minimum

Chapter 3

Programming

value VMIN in word W28 (W48) and the maximum value VMAX in word W29 (W49). Limiting is not performed on the SET OUT value in word W05 (W12).

W19 (W39) B15, B14, B13. Soft Fault Mode Selection. These bits select the PID module’s response for the loop when communication with the PC processor is broken. The PID module’s microprocessor continues to operate and is firmware programmed to respond to the fault. The PID module’s STAND-ALONE yellow LED indicator flashes when the module is in the soft fault mode.

NOTE: In order for the PID module to operate in the soft fault mode, the last state witch (switch 1) in the switch group assembly on the I/O chassis backplane must be set to the off position. As such, output of all other modules in the chassis will be de-energized when a major fault is detected by the PC processor.

NOTE: When the PID module enters the soft fault mode, it does not generate a manual request to relinquish control to the auto/manual station. However, if the PID module detects a hardware failure when in soft fault mode it will generate a manual request.

The soft fault operating modes are listed in Table 3.E.

323

Chapter 3

Programming

Figure 3.7

Control

ord B, Loop 1 W19 and Loop 2 W39

PID

x BIAS

PID

+ BIAS

W19(W39) B17 1=Multiply V

0=Add V

W19(W39) B16

1=Use output limiting W28, W29,

(W48,W49)

0=No limiting

W19(W39) B15,14,13

SOFT FAULT MODE SELECTION

0 0 0 Output set to minimum value 0 0 1 Output holds last value 0 1 0 Output will hold Set Analog

Output value if W01 B01=1. If W01 B01=0, module continues to perform closed loop control

1 0 0 PID module will perform closed

loop control (ignores set output)

1 1 1 Output set to maximum value

W19(W30) B12

1=T

A W20(W40) times 10 (x10)

0=No multiplier (x1)

W19(W39) B1

1=TB W35(W55) times 10 (x10) 0=No multiplier (x1)

W19(W39) B10

1=TC W36(W56) times 10 (x10) 0=No multiplier (x1)

x10 TC1

Expanded Loop

(-)

SP SIGN

(+)

x10

SCALING

MULTIPLIER

FOR

MULTIPLIER

FOR

K 1

Loop 1 W19

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

MULT (X)

BIAS 1

SUM (+)

LIMIT

OUTPUT1

SOFT FAULT

SELECTION CODE

x10 TA1

x10 TB1

MULTIPLIER

FOR

Loop 2 W39

MULT (X)

BIAS 2

SUM (+)

LIMIT

OUTPUT2

SOFT FAULT

SELECTION CODE

W19(W39) B07 1=Negative scaled set point value

0=Positive scaled set point value

W19(W39) B06

1=Scaling values W31, W32, (W51, W52) times 10 (x10) 0=No multiplier (x1)

W19(W39) B05,04

Multiplier for KP W07(W14) 0 0 K 0 1 K 1 0 K 1 1 K

W19(W39)

B03,02

Multiplier for KI W24(W44) 0 0 K 0 1 K 1 0 K 1 1 K

W19(W39)

B01,00

Multiplier for KD W25(W45) 0 0 K 0 1 K 1 0 K 1 1 K

Note: If you change a loop 1 or loop 2 parameter, you must initiate a load/enter sequence

P P P P

I I I I

D D D D

x1 /10 x10 x100

x10 TA2

x10 TB2

x10 TC2

(-)

SP SIGN

(+)

x10

SCALING

MULTIPLIER

FOR

MULTIPLIER

FOR

K 1

MULTIPLIER

FOR

11110

324

Chapter 3

Programming

Table 3.E Multiplier

Codes

W19(W39)

B15 B14 B13

0 0 0

0 0 1

0 1 0

1 0 0

1 1 1

Soft Fault Operating Mode

Analog output is set to the minimum value (+4mA or +1VDC).

Analog output holds the last value prior to the fault.

The PID module performs closed loop control unless W01 B01 = 1 for loop 1 (W01 B02= 1 for loop 2). If this bit is set prior to the soft fault, the SET OUT value in W05(W12) remains as the loop output.

The PID module performs closed loop control regardless of the status of W01 B01 (B02). If the loop output was the SET OUT value in W05(W12) when the soft fault occurred, the module reverts to PID control. This mode should be selected for interactive PC control.

Analog output is set to the maximum value (+20mA or +5VDC)

Each loop must be set independently

. No other codes are permitted.

W19 (W39) B12 Input Filter Time constant Multiplier. Reset to 0 the multiplier for the input filter time constant TA stored in word W20 (W40) is x1 (no multiplier). Set to 1 the multiplier is x10.

W19 (W39) B11 Lead Time Constant Multiplier. (XF) Reset to 0 the multiplier for the lead time constant TV stored in word W35 (W55) is x1. Set to 1 the multiplier is x 10.

W19 (W39) B10 Lag Time Constant Multiplier. (XF) Reset to 0 the multiplier for the lag time constant TC in word W 36 (W56) is x1. Set to 1 the multiplier is x10.

W19 (W39) B07 Scaled Set Point Sign. (XF) Reset to 0 the set point value in word W06 (W13) is positive. Set to 1 the value is negative. This bit has meaning only when set point scaling has been selected by 16 = 1 in word W30 (W50).

W 19 (W39) B06 Scaling Word Multiplier. (XF) This bit selects the multiplier for the following words:

325

Chapter 3

Programming

set point in word W06(W13) minimum scaling value in word W31(W51) maximum scaling value in word W32(W52) loop error in word W62(W69) read process variable in word W65(W72)

When this bit is reset to 0, the above values are multiplied x1. When set to 1, the values in words W31(W51) and W32(W52) are multiplied x10. The other words are multiplied x 10 only if the values are scaled.

NOTE: The multiplier bit B06 must be examined to determine the correct value of the loop error in word W62(W69) or the read process variable in word W65(W72) when either word is read by the PC processor.

W19(W38)B05, B04 Proportional Gain Multiplier. These two bits select the multiplier for the integral gain K

in word W24(W44)(table

3.F).

W19(W39) B03, B02 Integral Gain Multiplier. These two bits select the multiplier for the integral gain K

in word W24(W44)

(Table 3.F).

Table 3.F Multiplier

K K K K

Codes

P I D F

W19(W39) W19(W39) W19(W39) W30(W50)

B05 B03 B01 B07

0 0 1 1

B04 B02 B00 B06

0 1 0 1

Multiplier

/10

x10

x100

W19(W39)B01, B00 Derivative Gain Multiplier. These two bits select the multiplier for the derivative gain K

in word

W25(W45)(Table 3.F).

326

W20(W40)Input Filter Time Constant, TA. This word contains the time constant for the input digital filter. The digital filter is the equivalent of a single pole low pass filter. Data format is 4-digit BCD (99.99) with

Chapter 3

Programming

an implied decimal point. the x10 multiplier bit is B12 in word W19(W39). Range is 00.10 to 999.9. a value of zero implies no filter.

W21 (W41) Maximum Negative Error, EMN. This word contains the maximum negative error for the loop. This value can be used for alarm purposes and/or limiting. The alarm condition is indicated by W61(W68)B15. error limiting is selected by B12 = 1 in word W18(W38). Data format is 4-digit BCD with a range from 0000 to 4095. a negative value is implied.

W22(W42) Maximum Positive Error, EMP. This word contains the value used as the maximum positive error for the loop. This value can be used for alarm purposes and/or limiting. The alarm condition is indicated by W61(W68)B14. Error limiting is selected by B12 = 1 in word W18(W38). Data format is 4-digit BCD with a range from 0000 to 4095. a positive value is implied.

W23(W43) Dead Band, DB. This word contains the error dead band value. This value can be used for alarm purposes and/or setting the dead band range. The error dead band extends above and below zero error so that the dead band range is twice the dead band value. Dead band is selected by B11 = 1 in word W18(W38). The alarm condition is indicated by W61(W68)B11. Data format is 4-digit BCD with a range from 0000 to 4095 above and below zero error.

Any time the error value is outside the dead band, the actual error value will be used for computational purposes. As it crosses into the dead band, the error value continues to be used for computational purposes until it crosses zero. Once it crosses zero and as long as it remains in the dead band, the error value will be set to zero for computational purposes.

W24(W44) Integral Gain, K I (Reset Term 1/T I). If W02B00 is reset, the module uses the A-B value K I and this word contains the integral gain constant for the loop. If W02 B00 is set, the module uses the ISA value I/T I and the word contains the reset term for the loop. Data format is 4-digit BCD, 9.999 in units of inverse seconds (A-B) or inverse minutes (ISA), with implied decimal point. Multiplier bits W19(W39)B03, B02 can be selected for x1, divided by 10, x10, x100 (Table 3.F). By using multipliers, the range can be extended from .0000 to 999.9.

The integral term K I or reset term 1/T I must be greater than zero for the module to perform bumpless transfer. Reset or hold the integral term V I to zero by setting K I or 1/T I = 0.

327

Chapter 3

Programming

W25(W45) Derivative Gain, K D (Rate Term, Td). If W02 B00 is reset, the module uses the A-B value K D and this word contains the derivative gain constant for the loop. If W02 B00 is set, the modules uses the ISA value Td and this word contains the rate term for the loop. Data format is 4-digit BCD, 99.99 in units of seconds (A-B) or minutes (ISA), with implied decimal point. Multiplier bits W19(W39)B03, B02 can be selected by 1, divided by 10, x10, x100 (Table 3.F). By using multipliers, the range can be extended from 0.000 to 9999.

W26(W46) Integral Term Limit, V I MAX. This word contains the integral term limit for the loop. It can be used for alarm purposes and/or limiting. The alarm condition is indicated by W61(W68)B10. Integral term limiting is selected by B10 = 1 in word W18(W38). Data format is 4-digit BCD with a range from 0000 to 9999.

NOTE: When limiting is selected, lowering the value of V I MAX reduces the PID module’s ability to adjust the integral term. The performance of bumpless transfer could be hindered.

W27(W47) Derivative Term Limit, VD MAX. This word contains the derivative term limit for the loop. It can be used for alarm purposes and/or limiting. The alarm condition is indicated by W61(W68)B02. Derivative term limiting is selected by B02 = 1 in word W18(W38). Data format is 4-digit BCD with a range from 0000 to 9999.

W28(W48) Minimum Output Limit, VMIN. This word contains the minimum limit for the analog output that is determined by the PID module’s algorithm. This value can be used for alarm purposes and/or limiting. The alarm condition is indicated by W61(W68)B01. Output limiting is selected by B16 = 1 in word W19(W39). Data format is 4-digit BCD with range from 0000 to 4095. This limit has no effect on a SET OUT value downloaded from the PC processor into word W05(W12).

W29(W49) Maximum Output Limit, VMAX. This word contains the maximum limit for the analog output that is determined by the PID module’s algorithm. This value can be used for alarm purposes and/or limiting. The alarm is indicated by W61(W68)B00. Output limiting is selected by B16 = 1 in word W19(W39). Data format is 4-digit BCD with a range from 0000 to 4095. This limit has no effect on a SET OUT value downloaded from the PC processor into word W05(W12).

328

NOTE: The following words, W30(W50) through W36(W56), can be programmed if the expanded features (XF) of the loop are selected by

Chapter 3

Programming

W01 B14 = 1. The values of features not used must be zero. Section 3.6 describes expanded features such as cascade, decouple and feedforward.

W30(W50) Expanded Control Word (XF) This word together with loop control word A, W18(W38), and loop control word B, W19(W39), select the configuration for the loop. The expanded loop features are active when selected by W01 B14 = 1. Bits 17 through 00 of the expanded control word are defined below and summarized in Figure 3.8 for loop 1 word W30 and loop 2 word W50.

W30(W50)B17 Process Variable Scaling. (XF) Reset to 0 inhibits process variable scaling. Set to 1 enables the scaling limits SMIN and SMAX in words W32(W51) and W32(W52) respectively to determine the scaled value of the process variable. The scaled or unscaled process variable will be read by the PC processor in word W65(W72). Refer to section titled Scaling for additional information about scaling.

W30(W50)B16 Set Point Scaling. (XF) Rest to 0 inhibits set point scaling. Set to 1 the module interprets this word as a scaled value based on the scaling limits SMIN and SMAX IN WORD W32(W51) and W32(W52), respectively. Refer to section titled Scaling for additional information about scaling.

329

Chapter 3

Programming

Figure 3.8 Expanded

Control W

Loop 1 W30

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

SCALE

PV1

SCALE SP1

SCALE

PV2

SCALE SP2

SCALE ERROR1

SCALE ERROR2

DECOUPLE0TIEBACK

FFI1

TIEBACK

FFI2

NEG.

FFI1

POS.

NEG.

FFI2 POS.

FFI1

FFI2

Loop 2 W50

W30(W50) B07,06 Multiplier for KF 34(W54)

0 0 K

0 1 K

/10

x10

1 0 K

1 1 K

x100

ord, Loop 1 W30 and Loop 2 W50

W30(W50) B17 1=Use scaling for PV W65

W30(W50) B16 1=Use scaling for SP W06(W13)

W30(W50) B15 1=Use scaling for ERROR W62

W30(W50) B14 1=Decouple Loop 1 to Loop 2 in W30, only

W30(W50) B13 1=FFI from hardware Tieback input

W30(W50) B12 1=Change FFI to a negative value

W30(W50) B11 1=Perform square root FFI

W30(W50) B10 1=Multiply FF term by K

KFI X [FFI+FF0]

KF2 X

[FFI+FF0]

MULTIPLIER FOR

LEAD/LAG

0=No scaling, nonscaled value returned

0=No decoupling (Set W50 B14=0)

0=FFI from PC Processor W10(W17)

0=Maintain FFI as a positive value

0=No square root

0=No multiplication

(-)

SMIN1

(+)

(-)

SMIN2

(+)

(-)

SMAX1

(+)

(-)

SMAX2

(+)

BIAS1

PID

BIAS2

PID

NEG.

BIAS1

POS.

NEG.

BIAS2

POS.

CASCADE

LP1 TO SP LP2

330

W30(W50) B05 1=Enabel lead/lag W35,36 (W55,W56)

0=No lead/lag

W30(W50) B04 1=Negative value for SMIN W31(W51)

0=Positive value for SMIN

W30(W50) B03 1=Negative value for SMAX W32(W52)

0=Positive value for SMAX

W30(W50) B02 1=Set BIAS from PC Processor W08(W15)

0=PID Algorithm BIAS(FFV)

W30(W50) B01 1=Change sign of BIAS(FFV)

0=Maintain sign

W30 B00 1=Cascade Loop 1 into Loop 2 (in W30 only)

0=No cascade (Set W50 B00=0)

Note: If you change a loop 1 or loop 2 parameter, you must initiate a load/enter sequence

11111

Chapter 3

Programming

W30(W50)B15 Error Scaling. (XF) Reset to 0 inhibits loop error scaling. Set to 1 enables the scaling limits SMIN and SMAX in words W31(W51) and W32(W52) respectively to determine the scaled value of the loop error. The scaled or unscaled loop error will be read by the PC processor in word W62(W69). Refer to section titled scaling for additional information about scaling.

W30(W50)B14 Decouple. (XF) Reset to 0 inhibits decoupling. Set to 1 enables decoupling. The loop 1 PID calculation VPID 1 is used for the feedforward input FFI to the loop 2 control algorithm. Decoupling overrides the feedforward input FFI for loop 2. (W50 B14 for loop 2 must be reset to 0.) Refer to section titled Closed Loop Control for additional information about decoupling.

W30(W50)B13 Source of Feedforward Input, FFI. (XF) Reset to 0 selects the value in word W10(W17) as the feedforward input for the loop. Set to 1 selects the tieback input as the feedforward input.

W30(W50)B12 Feedforward Input Sign. (XF) Reset to 0 maintains the positive value of the feedforward input for the loop. Set to 1 changes the value to negative.

W30(W50)B11 Feedforward Input Square Root. (XF) Reset to 0 inhibits the square root function. Set to 1 enables the normalized square root of the feedforward input, (square root of FFI) x (square root of 4095). Square root allows the linearization of differential pressure type flow transducers.

W30(W50)B10 Feedforward Term Multiplication. (XF) Reset to 0 inhibits multiplication. Set to 1 enables the feedforward term (feedforward offset + feedforward input) to be multiplied by the feedforward gain in word W34(W54). The result is K

x (FFO +

FFI).

W30(W50)B07, 06 Feedforward Gain Multiplier. (XF) These two bits select the multiplier for feedforward gain K

in word

W34(W54)(Table 3.F).

W30(W50)B05 Lead/Lag. (XF) Reset to 0 inhibits the lead/lag function. Set to 1 enables the lead/lag function. The values for the lead and lag time constants are contained in words W35(W55) and W36(W56), respectively. Refer to section titled Lead/Lag Filter for additional information about the lead/lag filter.

331

Chapter 3

Programming

W30(W50)B04 Minimum Scaling Sign. (XF) Reset to 0 the sign for SMIN in word W32(W51) is positive. Set to 1 the sign is negative.

W30(W50)B03 Maximum Scaling Sign. (XF) Reset to 0 the sign for SMAX in word W32(W52) is positive. Set to 1 the sign is negative.

W30(W50)B02 Source of Bias. (XF) Reset to 0 the feedforward value is the loop bias. Set to 1 the bias value in word W08(W15) is the loop bias.

W30(W50)B01 Bias (FFV) Sign. (XF) Reset to 0 the sign of the feedforward/bias term remains the same. Set to 1 the sign is reversed.

W30(W50)B00 Cascade. (XF) Reset to 0 inhibits the cascade feature. Set to 1 cascades the calculated output of loop 1 into the set point of loop 2. (W50 B00 for loop 2 must be reset to 0). Refer to section titled Closed Loop Control for additional information about cascading.

W31(W51) Minimum Scaling Value SMIN. (XF) This word contains the minimum (or bottom) scale value of the loop scaling algorithm. This value is in engineering units. Data format is 4-digit BCD (9999 maximum). The sign bit B04 in word W30(W50) and the x10 multiplier bit B06 in word W19(W39) must be considered to determine the value. The range can be +

99990. Refer to section titled Scaling for additional

information about scaling.

W32(W52) Maximum Scaling Value, SMAX. (XF) This word contains the maximum (or top) scale value of the loop scaling algorithm. This value is in engineering units. Data format is 4-digit BCD (9999 maximum). The sign bit B03 in word W30(W50) and the x10 multiplier bit B06 in word W19(W39) must be considered to determine the value. The range can be +

99990. refer to section titled Scaling for additional

information about scaling.

332

W33(W53) Feedforward Offset, FFO. (XF) This word contains the feedforward offset of the loop. It is added to the feedforward input. Data format is 4-digit BCD (9999 maximum).

Chapter 3

Programming

W34(W54) Feedforward Gain, K F. (XF) This word contains the feedforward gain constant for the loop. Data format is 4-digit BCD (99.99 dimensionless with implied decimal point. Multiplier bits B07, B06 in word W30(W50) can be selected for x1, divided by 10, x10, 1100 (Table 3.F). The range can be 0.000 to 9999 when using the multipliers.

W35(W55) Lead Time Constant, TB. (XF) This word contains the lead time constant for the loop. The lead/lag feature is selected by bit B05 in word W30(W50). To disable the lead portion of the filter, reset TB to zero. Data format is 4-digit BCD (99.99 in units of seconds) with implied decimal point. By using the x10 multiplier bit B11 in word W19(W39), the range can be 00.00 to 999.9.

W36(W56) Lag Time Constant, TC. (XF) This word contains the lag time constant for the loop. The lead/lag feature is selected by bit B05 in word W30(W50). To disable the lag portion of the algorithm, reset TC to zero. Data format is 4-digit BCD (99.99 in units of seconds) with implied decimal point. By using the x10 multiplier bit B10 in word W19(W39), the range can be 00.00 to 999.9.

NOTE: There is no word number 37 to program. By omitting W37, the storage words for loop 1 and loop 2 parameters are exactly 20 counts apart.

Example: W20 Integral Gain 1 (W40 Integral Gain 2)

Status Block: W57W74

The status block is a read block transfer file of up to 18 words which is used to report loop status, alarm and diagnostic information and to prompt the proper block transfer sequences.

Only words W57 through W67 will be read if the module is selected for loop 1 operation. The entire block (words W57 through W74) is read if the module is selected for two-loop operation.

The 18 words that comprise the status block are defined in the paragraphs that follow. Table 3.G lists the status block words. All the words of the dynamic block, loop block and status block are listed in Table 3.J, in Figure 3.13 and Figure 3.14 found at the end of section titled Word and Bit Definitions.

333

Chapter 3

Programming

Table 3.G

Block W

Status

ords

Both Loops W57 W58 W59 W60

Loop 1 W61 W62 W63 W64 W65 W66 W67

Loop 2 W68 W69 W70 W71 W72 W73 W74

Word

Title Abbreviation

For future use Alarm Next Block Start Address

ime/Diagnostic

Loop T

Loop 1 Status Loop 1 Error Read Loop 1 Output Read Analog Input 1 Read Process V Read T

ieback Input 1

Read Feedforward V

Loop 2 Status Loop 2 Error Read Loop 2 Output Read Analog Input 2 Read Process V Read T

ieback Input 2

Read Feedforward V

ariable 1

alue 1

ariable 2

alue 2

ERROR1

READ V1

READ IN1

READ PV1

READ TIE1

READ FFV1

ERROR2

READ V2

READ IN2

READ PV2

READ TIE2

READ FFV2

W57 This word is reserved for future use. It will contain 0000.

W58 Alarm Word. This word contains alarm information for both

loops. It contains information concerning possible programming errors and operating faults. Specific loop faults are found in the status word W61 for loop 1 (W68 for loop 2). Bits 17 through 00 of alarm word W58 are defined below and summarized in Figure 3.9.

W58 B17, B16 Block Identifiers. These two bits identify the status block. Both bits will be read as 0 by the PC processor.

W58 B15 Dynamic Block Error. Set to 1 the previously transferred dynamic block contained a programming error. To identify the error, W01 B07 must be set to 1 so that the loop time/diagnostic word W60 can report diagnostic information. The upper byte of W60 will contain the dynamic block error code. See word W60 below for additional information.

W58 B14 Loop Block Error. Set to 1 the previously transferred loop 1 or loop 2 block contained a programming error. To identify

334

Chapter 3

Programming

the error, W01 B07 must be set to 1 so that the loop time/diagnostic word W60 can report diagnostic information. The lower byte of W60 will contain the error code. See word W60 below for additional information.

W58 B13 Power-Up. After the PID module has received the first valid dynamic block with the load bit W01 B06 =1, this bit will be reset to 0. Note that this does not mean that the PID module is programmed, only that the first dynamic block has been processed.

After the PID module has gone through its initial power-up procedure or after the restoration of +5VDC, it will set bit W58 B13 to 1. This occurs when the module has cleared all internal memory and is waiting to be programmed by block transfers to complete the initial load/enter sequence. See section titled Power-Up Load/Enter Sequence for additional power-up load/enter sequence information.

W58 B12 Ready. Set to 1 indicates that the load portion of the load/enter sequence has been successfully completed. The ready bit should be used to initiate the setting of the enter bit to complete the sequence. After the enter bit is received by the PID module, the ready bit will be reset to 0.

Before the enter bit is received by the PID module, a ready bit status of 0 indicates an error was detected in either the dynamic block or a loop block during the load portion of the load/enter sequence. The error must be corrected before the ready bit can be set to 1. See section titled Load/Enter Sequence or additional Load/enter sequence information.

335

Chapter 3

Programming

Figure 3.9

Alarm

ord W58

W58 B17 will be returned as 0

W58 B16 will be returned as 0

W58 B15 1=indicates programming error in the dynamic block

W58 B14 1=indicates programming error in either loop 1 or loop 2 block

W58 B13 1=in powerup mode

W58 B12 1=ready

W58

W58 B11 1=loss of +

15V dc power

W58 B10 1=in soft fault mode

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

DYNAMIC BLOCK

ERROR

LOOP BLOCK ERROR

POWER-UP READY

LOSS OF + 15VDC POWER

SOFT FAULT

00 00 00 00

W58 B07B00 will be returned as 0

11112

336

Chapter 3

Programming

W58 B11 Loss of +15VDC. Reset of 0 indicates that power is present. Set to 1 indicates that the external +15VDC power is not present. When +15VDC power is lost, the PID module generates a manual request by closing the contact output.

W58 B10 Soft Fault Mode. Reset to 0 indicates that module is in the normal operating mode. Set to 1 indicates the PID module is operating in the soft fault mode. The soft fault response is programmed by W19(W39) B15,14,13 (Table 3.E). Soft fault reset is accomplished by setting W01 B10 to 1.

W58 B07 through B00. These bits are reserved for future use and will be reset to 0.

W59 Next Block Start Address. The PID module controls the block transfer programming sequences by determining which block should be transferred next. This word contains the data table address of the first word in the file associated with the next write block transfer. The PID module reports to the PC processor the block start addresses programmed in word W03 for the dynamic block, in word W04 for the loop 1 block, or in word W11 for the loop 2 block. The PID module performs no data manipulation on the next block start address in word W59.

W60 Loop Time/Diagnostic. This is a dual function word. This word can report either the loop update time or diagnostic information. Its function is established by W01 B07. When W01 B07 = 0, W60 reports loop time. When W01 B07 = 1, W60 reports diagnostic information (Figure 3.10).

When reporting loop time, the data format is 0-100 milliseconds. Bit W60 B17 will be set to 1 to indicate when this word is reporting loop time. The loop update time is nominally 100msec. The loop update time is the time between successive module scans of the analog inputs. Only one block transfer will be allowed during a loop update (Figure 3.11).

When reporting diagnostics, two separate error codes can be reported. The error code is a 2-digit BCD value. The upper byte will indicate a dynamic block error code. The lower byte will indicate a loop block error code. If more than one error code exists, the first error code will be displayed until it is corrected. Then the next error code will be displayed. Table 3.H and Table 3.I contain error code definitions.

337

Chapter 3

Programming

W61(W68) Loop Status. This word indicates various alarm conditions for the corresponding loop and contains sign information for certain status block words. Bits 17 through 00 of the loop status word are defined below and summarized in Figure 3.12 for loop 1 word W61 and loop 2 word W68.

Figure 3.10

ime/Diagnostic Word W60

Loop

a) Loop time

Selected by W01 B07=0. XYZ = Loop time in milliseconds

17161514131211100706050403020100

1000

XYZ

Read Input 1

Read Input 2

Calc

Output

b) Diagnostics

Selected by W01 B07=1 AB, CD = Diagnostic error codes

17161514131211100706050403020100

BCDA

Upper byte two digit BCD code indicates which word in the dynamic block is in error.

Lower byte two digit BCD code indicates which word in the loop 1 or loop 2 block is in error

Figure 3.11 Loop

Calc

Output

Update T

Output

Set

ime

Set

Output

11113

100 msec

338

PID Algorithm Internal Housekeeping

Nominal Loop Update Time 100 msec

11114

Table 3.H

Upper Byte Programming Error Codes

W60

Chapter 3

Programming

BCD Code

02 03 04 05 06 07 08 09 10

11 12 13 14 15 16 17

BCD Code

60 61 62

65 66 67 68

Dynamic Block W

Incorrect number of words for the dynamic block (1loop or 2loop configuration) Not currently used as error code. Not currently used as error code. Not currently used as error code. W05 is above maximum or has illegal BCD value. W06 has illegal BCD value. W07 has illegal BCD value. W08 has illegal BCD value. W09 has illegal BCD value. W10 has illegal BCD value. Not currently used as error code. W12 is above maximum or has illegal BCD value. W13 has illegal BCD value. W14 has illegal BCD value. W15 has illegal BCD value. W16 has illegal BCD value. W17 has illegal BCD value.

Dynamic Block W

Less than 10 words transferred (1loop configuration) Less than 17 words transferred (2loop configuration). Dynamic block identifier bits B17, B16 are not set correctly in W01, and/or W18, and/or W38. Less than 13 words transferred (1 loop configured with SET OUT value of loop 2 requested). Read and write block transfers are out of sequence. Status block must be transferred first. The load bit and enter bit must be set concurrently The enter bit must not be set before the ready bit is returned The verify and load bits must not be set concurrently During the powerup load/enter sequence, the enter bit must be set to complete the sequence. During the load portion of the powerup load/enter sequence, the dynamic block can be transferred only once.

ord Errors

339

Chapter 3

Programming

Table 3.I W60 Lower Byte Programming Error Codes

BCD Code

19 20 21 22 23 24 25 26 27 28 29

31 32

33 34 35 36

Dynamic Block W

Loop 1 constants block was not transferred in the load/enter sequence. W19 has illegal soft fault code 01 W20 has illegal BCD value. W21 is above maximum or has illegal BCD value. W22 is above maximum or has illegal BCD value. W23 is above maximum or has illegal BCD value. W24 has illegal BCD value. W25 has illegal BCD value. W26 has illegal BCD value W27 has illegal BCD value. W28 is above maximum or has illegal BCD value. W29 is above maximum, has illegal BCD value, or is less than W28. W30 has cascade or decouple selected when only loop 1 is selected. W31 has illegal BCD value. W32 has illegal BCD value or is less than or equal to W31 value.. W33 has illegal BCD value. W34 has illegal BCD value. W35 has illegal BCD value. W36 has illegal BCD value.

ord Errors

1, 101, or 1

10.

BCD Code

39 40 41 42 43 44 45 46 47 48 49

50 51 52 53 54 55 56

Loop 2 Word Errors

Loop 2 constants block was not transferred in the load/enter sequence. W39 has illegal soft fault code o1 W40 has illegal BCD value. W41 is above maximum or has illegal BCD value. W42 is above maximum or has illegal BCD value. W43 is above maximum or has illegal BCD value. W44 has illegal BCD value. W45 has illegal BCD value. W46 has illegal BCD value. W47 has illegal BCD value. W48 is above maximum or has illegal BCD value. W49 is above maximum, has illegal BCD value, or is less than W48. Not used W51 has illegal BCD value. W52 has illegal BCD value or is less than or equal to W51. W53 has illegal BCD value. W54 has illegal BCD value. W55 has illegal BCD value. W56 has illegal BCD value

1, 101, or 1

10.

340

Chapter 3

Programming

BCD Code

Block T

ransfer Errors

Communication Fault. The number of block transfer words exceeds the number expected by PID module. Less than 12 words transferred in the standard loop constant block. Less than 19 words transferred in the expanded loop constants block. Loop 1 or loop 2 constants block can be transferred only in a load/enter sequence.

341

Chapter 3

Programming

Figure 3.12 Loop Status W

ord, Loop 1 W61 and Loop 2 W68

W61(W68) B17 1=ERROR W62(W68) has negative value

0=ERROR has positive value

W61(W68) B16 1=Scaled PV W65(W72) has negative value

0= positive value

W61(W68) B15 1=Error < EMN W21(W41)

W61(W68) B14 1=Error > EMP W22(W42)

W61(W68) B13 1=FFV has a negative value

0=FFV has a positive value

W61 B12 1=Load/enter sequence is complete, in W61 only.

W61(W68) B11 1=Error is within the dead band (W23)

0=Error is outside the dead band

W61(W68) B10 1=Integral term > V

MAX W26(W46)

Loop 1 W61

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

LOAD/

NEG. ERROR1 POS.

NEG. ERROR2 POS.

NEG. SCALED PV POS.

NEG.

SCALED PV

POS.

E<EMN1

E<EMN2

E>EMP1

E>EMP2

NEG. FFV1

POS.

NEG. FFV2

POS.

ENTER

COMPLETE

WITHIN EROR DEAD BAND

OUTSIDE

WITHIN EROR

DEAD BAND

OUTSIDE

V > V

MAX

V > V

MAX

LOSS OF ANALOG INPUT 1

LOSS OF ANALOG INPUT 2

LOSS OF TIEBACK INPUT 1

LOSS OF TIEBACK INPUT 2

MANUAL MODE

AUTOMATIC

MANUAL MODE

AUTOMATIC

COMPLETE POWER-UP IN PROCESS

V >4095

V > V

MAX

V > V

MAX

Loop 2 W68

W61(W68) B07 1=Loss of analog input

W61(W68) B06 1=Loss of tieback input

W61(W68) B05 1=Auto/manual station in the manual mode

0=Loop is in the automatic mode under PID module control

W61(W68) B04 1=Powerup sequence is complete, in

W61 only 0=In powerup mode; module is

unprogrammed

V<VMIN

V>VMAX

W61(W68) B03 1=Proportional term > 4095

W61(W68) B02 1=Derivative term > V

MAX W27(W47)

W61(W68) B01 1=Algorithm output < VMIN W28(W48)

W61(W68) B00 1=Algorithm output > VMAX W29(W49)

342

11115

Chapter 3

Programming

W61(W68)B17 Sign of Loop Error. Reset to 0 the sign of the error value in word W62(W69) is positive. Set to 1 the sign is negative.

W61(W68)B16 Sign of Read Process Variable. Reset to 0 the sign of the scaled process variable in word W65(W72) is positive. Set to 1 the sign is negative. This bit has meaning only when process variable scaling has been selected by W30(W50)B17 = 1.

W61(W68)B15 Error <Maximum Negative Error. Reset to 0 the error value is greater than or equal to the maximum negative error EMN in word W21(W41). Set to 1 the loop error is less than the maximum negative error. The bit status is reported whether or not error limiting is selected.

W61(W68)B14 Error>Maximum Positive Error. Reset to 0 the error value is less than or equal to the maximum positive error EMP in word W22(W42). Set to 1 the loop error is greater than the maximum positive error. The bit status is reported whether or not error limiting is selected.

W61(W68)B13 Sign of Feedforward Value. Reset to 0 the sign of the feedforward value in word W67(W74)is positive. Set to 1 the sign is negative.

W61(W68)B12 Load/Enter Complete. Reset to 0 when the module receives a dynamic block transfer with the load bit W01 B06 = 1. Bit B12 will be set to 1 at the completion of the load/enter sequence after the module successfully processes the dynamic block with the enter bit W01 B03 =1. The bit will remain set to 1 until a new load/enter sequence is attempted. (W68 B12 in loop 2 will be returned as 0.) Refer to sections titled Power-Up Load/Enter Sequence and Load/Enter Sequence for additional information.

W61(W68)B11 Error within Dead Band. Reset to 0 the error for the loop is outside the dead band established by the value in word W23(W43). Set to 1 the error is inside the dead band. The bit status is reported whether or not the dead band feature is selected.

NOTE: When the error enters the dead band range, the bit will not be set until the error reaches (crosses) zero. It will be reset when the error exceeds the dead band value.

343

Chapter 3

Programming

W61(W68)B10 Integral Term>Integral Term Limit. Rest to 0 the integral term V I is less than or equal to the integral term limit V I MAX in word W26(W46). Set to 1 the integral term is greater than V I MAX. The bit status is reported whether or not integral term limiting is selected.

W61(W68)B07 Loss of Analog Input. Rest to 0 the analog input signal from an input device is present and can be found in word W64(W71). Set to 1 the hardware analog input is less than the minimum value of +4mA or 1VDC. A loss of hardware analog input will be detected whether or not a PV value is downloaded from the PC processor into word W09(W16).

The loss of a hardware analog input will cause the corresponding loop output to be held at its last value until the input is restored. However, if the process variable has been downloaded from the PC processor into word W09(W16), loss of a hardware analog input will be detected but will not cause the analog output to be held.

NOTE: When downloading PC values from the PC processor when an input device is not connected, jumper the INPUT (+LEAD) terminal to the +15VDC terminal to prevent the loss of input bit W61(W68)B07 from being set.

NOTE: Loss of input detection when analog inputs are configured in voltage mode requires the use of 10K ohm 1/4 watt resistor. The resistor must be connected between the INPUT (+LEAD) and (-LEAD) terminals to ensure loss of input detection for an open or short circuit in one or both leads of the input device. The module input impedance is thereby reduced to 10k ohms. A resistor is not required for loss of input detection for current mode analog inputs.

If either decoupling or cascading is selected and the hardware analog input to loop 1 is lost, the output for both loops will be held regardless of the status of the loop 2 inputs.

The loss of a hardware analog input is indicated by bit B07 of loop status word W61(W68) and bit B02 of the status monitor byte.

344

W61(W68)B06 Loss of Tieback Input. Reset to 0 indicates that the tieback input signal is present and can be found in word W66(W73). Set to 1 indicates that the input is less than the minimum value of +4mA or +1VDC.

Chapter 3

Programming

The loss tieback input will cause the corresponding loop output to be held at its last value until the input is restored.

If either decoupling or cascading is selected and the tieback input to loop 1 is lost, the output for both loops will be held regardless of the status of the loop 2 inputs.

When the tieback input is used as a hardware analog input, loss of input detection does not require the use of an external resistor.

The loss of a tieback input is indicated by bit B06 or loop status word W61(W68) and bit B02 of the status monitor byte.

W61(W68)B05 Manual Mode. Reset to 0 indicates that the PID module is controlling the analog output signal to the actuator. Set to 1 indicates that the module has relinquished control to the user supplied auto/manual station, placing the station in the manual mode. Manual operation could have been initiated at the auto/manual station by the loss of analog power, or by setting W01 B00 to 1.

W61(W68)B04 Power-Up Complete. Rest to 0 at power-up. After a valid power-up load/enter sequence initializes the module, this bit is set to 1. (W68 B04 for loop 2 will be reset.) Refer to section titled Load/Enter Sequence for additional information.

W61(W68)B03 Proportional Term>4095. Reset to 0 indicates that the proportional term V (full scale). Set to 1 indicates that V

for the loop is less than or equal to 4095

is greater than 4095.

W61(W68)B02 Derivative Term>VD MAX. Reset to 0 indicates that the derivative term VD for the loop is less than V 1 indicates that V

is greater than VD MAX IN W27(W47).

MAX. Set to

W61(W68)B01 ALGORITHM OUTPUT<Minimum Output. Reset to 0 indicates that the analog output is in range and greater than or equal to the minimum output value VMIN in word W28(W48). Set to 1 indicates that the analog output computed by the PID module is less than the VMIN. The bit status is reported whether or not output limiting has been selected. This status bit does not monitor a SET OUT value downloaded from the PC processor into word W05(W12).

345

Chapter 3

Programming

W61(W68)B00 Algorithm Output>Maximum Output. Reset to 0 indicates that the analog output is in range and less than or equal to the maximum output value VMAX in word W29(W49). Set to 1 indicates that the analog output computed by the PID module is greater than VMAX. The bit status is reported whether or not output limiting has been selected. This status bit does not monitor a SET OUT value downloaded from the PC processor into word W05(W12).

W62(W69) Loop Error, ERROR. This word contains the loop error. Data format is 4-digit BCD. The sign bit B17 in word W61(W668) can establish an unscaled range of 0 to +

4095.

When error scaling is selected by W30(W50)B15 = 1, the loop error can be reported in user-selected engineering units. The sign bit B17 in word W61(W68) and the x 10 multiplier bit B06 in word W19(W39) must be examined to determine the value. The scaled range can be +

99990. Refer

to section titled Scaling.

W63(W70) Read Loop Output, READ V. This word contains the final analog output value as determined by the module’s PID algorithm. Data format is 4-digit BCD or 12-bit binary. Format is selected by W01 B12. Range is 0000 to 4095.

NOTE: When a SET OUT value is downloaded from the PC processor into word W05(W12) by setting W01 B01(W01 B02) = 1, the SET OUT value will override the analog output value. However, the value reported in W63(W70) will always be the analog output value as determined by the module’s PID algorithm, not the SET OUT value.

W64(W71) Read Analog Input, READ IN. This is the actual input value read by the analog-to-digital converter in the module. Data format is 4-digit BCD or 12-bit Binary. Format is selected by W01 B12. Range is 0000 to 4095.

W65(W72) Read Process Variable, READ PV. This is the actual process variable used by the PID module. Data format is 4-digit BCD. The unscaled range is 0000 to 4095.

346

When process variable scaling is selected by W30(W50)B17 = 1, READ PV can be reported in user-chosen engineering units. The sign bit B16 in word W61(W68) and the x10 multiplier bit B06 in word W19(W39) must

Chapter 3

Programming

be examined to determine the value. The range can be +99990. Refer to section titled Scaling.

W66(W73) Read Tieback Input, READ TIE. This is the actual value read by the analog-to-digital converter in the module. Data format is 4-digit BCD or 12-bit binary. Format is selected by W01 B12. Range is 0000 to

4095.

W67(W74) Read Feedforward Value, Read FFV. This is the feedforward computation as performed by the PID module. Data format is 4-digit BCD with sign bit B13 in word W61(W68) allowing a range of

9999.

Control and status words are summarized in Figure 3.13, Figure 3.14 and Table 3.J.

347

Chapter 3

Programming

Figure 3.13

Control

Master Control Word W01

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

Loop 1 Control Word A W18

2 LOOPS

PC PV1 PID

LOOP 1

EXPANDED

STANDARD

PV1

CALIB BINARY

PV-SP ERROR1 SP-PV

LIMIT ERROR1

BCD

ord Summary

BINARY

BCD

DEAD BAND

SOFT FAULT RESET

V1 MAX LIMIT

DIAG

LOOP TIME

PROPORTIONAL

ERROR

FUNCTION

LOAD

VERIFY

CODE

INTEGRAL ERROR FUNCTION

ENTER

DERIV. ERR.

Error

SET

OUTPUT 2

VD MAX

LIMIT

OUTPUT 1

SET

HOLD PID1

MANUAL

REQUEST

HOLD BIAS1

Loop 1 Control Word B W19

LIMIT

OUTPUT1

SOFT FAULT

SELECTION CODE

MULT (X)

BIAS 1 SUM (+)

Expanded Loop 1 Control Word W30

SCALE

PV1

SCALE SP1

SCALE ERROR1

Loop 2 Control Word A W38

PV2 PID

Loop 2 Control Word B W39

MULT (X)

BIAS 2

SUM (+)

LIMIT

OUTPUT2

SELECTION CODE

DECOUPLE0TIEBACK

PV2

SOFT FAULT

FFI1

PV-SP ERROR2 SP-PV

x10 TA1

NEG.

FFI1

POS.

LIMIT ERROR2

x10 TA2

x10 TB1

FFI1

DEAD BAND

x10 TB2

x10 TC1

I X

[FFI+FF0]

V1 MAX LIMIT

x10 TC2

Expanded Loop

(-)

(+)

MULTIPLIER FOR

ERROR

FUNCTION

x10

SCALING

SP SIGN

PROPORTIONAL

Expanded Loop

(-)

SP SIGN

(+)

x10

SCALING

HOLD

BIAS2

MULTIPLIER

LEAD/LAG

FOR

SMIN1

INTEGRAL ERROR FUNCTION

MULTIPLIER

FOR

(-)

(+)

MULTIPLIER

(-)

SMAX1

(+)

DERIV. ERR.

Error

MULTIPLIER

FOR

K 1

FOR

K 1

BIAS1

VD MAX

PID

LIMIT

NEG.

BIAS1

POS.

HOLD PID2

MULTIPLIER

FOR

CASCADE

LP1 TO SP LP2

MULTIPLIER

FOR

Expanded Loop 2 Control Word W50

2 X

SCALE

PV2

SCALE SP2

SCALE ERROR2

TIEBACK

FFI2

NEG.

FFI2 POS.

FFI2

[FFI+FF0]

Note: If you change a loop 1 or loop 2 parameter, you must initiate a load/enter sequence.

348

MULTIPLIER FOR

KFI

LEAD/LAG

(-)

SMIN2

(+)

(-)

SMAX2

(+)

BIAS2

PID

NEG.

BIAS2

POS.

11116

Chapter 3

Programming

Figure 3.14

Status

Alarm Word W58

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

DYNAMIC BLOCK

ERROR

Status Monitor Byte SMB

LOOP BLOCK ERROR

POWER-UP READY

ord Summary

LOSS OF + 15VDC POWER

SOFT FAULT

00 00 00 00

07 06 05 04 03 02 01 00

AARM

00 1

CONDITION

POWERUP LOSS OF

AN INPUT

LOSS OF + 15VDC POWER

SOFT FAULT MODE

Loop 1 Status Word W61

17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00

LOAD/

NEG. ERROR1 POS.

NEG. SCALED PV POS.

E<EMN1

E>EMP1

NEG. FFV1

POS.

ENTER

COMPLETE

WITHIN EROR DEAD BAND

OUTSIDE

V > V

MAX

LOSS OF ANALOG INPUT 1

LOSS OF TIEBACK INPUT 1

MANUAL MODE

AUTOMATIC

COMPLETE

POWER-UP IN PROCESS

V >4095

V > V

MAX

Loop 2 Status Word W68

NEG. ERROR2 POS.

NEG.

SCALED PV

POS.

E<EMN2

E>EMP2

NEG. FFV2

POS.

WITHIN EROR

DEAD BAND

OUTSIDE

V > V

MAX

LOSS OF ANALOG INPUT 2

LOSS OF TIEBACK INPUT 2

MANUAL MODE

AUTOMATIC

V >4095

V > V

MAX

V<VMIN

V>VMAX

11117

349

Chapter 3

Programming

Table 3.J

ord Summary

DYNAMIC BLOCK

W01 W02 W03

Master Control W Control W Dynamic Block Start

Address W04 W05 W06 W07 W09 W09 W10

W11 W12 W13 W14 W15 W16 W17

Loop 1 Block Start Address

Set Analog Output 1

Set Point 1

Proportional Gain 1

Bias 1

Set Process V

Set Feedforward Input 1

Loop 2 Block Start Address

Set Analog Output 2

Set Point 2

Proportional Gain 2

Bias 2

Set Process V

Set Feedforward Input 2

ord

ariable 1

ariable 2

SET OUT1 SP1 K

BIAS 1 SET PV1 SET EFFI1

SET OUT 2 SP2 K

BIAS 2 SET PV2 SET FFI2

STA

TUS BLOCK

W57 W58 W59 W60 W61 W62 W63 W64 W65 W66 W67 W68 W69 W70 W71 W72 W73 W74

For Future Use Alarm (both loops) Next Block Start Address Loop T Loop 1 Status Loop 1 Error Read Loop 1 Output Read Analog Input 1 Read Process V Read T Read Feedforward V Loop 2 Status Loop 2 Error Read Loop 2 Output Read Analog Input 2 Read Process V Read T Read Feedforward V

LOOP 1 BLOCK LOOP 2 BLOCK

W18 W19 W20 W21 W22 W23 W24 W25 W26 W27 W28 W29 W30

W31 W32 W33 W34 W35 W36

Loop 1 Control Word A

Loop 1 Control Word B

Input Filter Time Constant 1

Maximum Negative Error 1

Maximum Positive Error 1

Dead Band 1

Integral Gain 1

Derivative Gain 1

Integral T

Derivative T

erm Limit 1

erm Limit 1 Minimum Output Limit 1 Maximum Output Limit 1 Loop 1 Expanded Control Word Minimum Scaling V Maximum Scaling V Feedforward Of

alue 1

fset 1 Feedforward Gain 1 Lead Time Constant 1 Lag T

ime Constant 1

TA1 EMN1 EMP1 DB1

MAX1

VMIN1 VMAX1

SMIN1 SMAX1 FFO1

TB1 TC1

W38 W39 W40 W41 W42 W43 W44 W45 W46 W47 W48 W49 W50

W51 W52 W53 W54 W55 W56

Loop 2 Control Word A Loop 2 Control Word B Input Filter Time Constant 2 Maximum Negative Error 2 Maximum Positive Error 2 Dead Ban 2 Integral Gain 2 Derivative Gain 2 Integral T Derivative T Minimum Output Limit 2 Maximum Output Limit 2 Loop 2 Expanded Control Word Minimum Scaling V Maximum Scaling V Feedforward Of Feedforward Gain 2 Lead Time Constant 2 Lag T

ime/Diagnostic

ariable 1

ieback Input 1

ariable 2

ieback Input 2

erm Limit 2

fset 2

ime Constant 2

alue 1

alue 2

ERROR1 READ V1 READ IN1 READ PV1 READ TIE1 READ FFV1

ERROR2 READ V2 READ IN2 READ PV2 READ TIE2 READ FFV2

TA2 EMN2 EMP2 DB2

MAX2

VMIN2 VMAX2

SMIN2 SMAX2 FFO2

TB2 TC2

Note: If you change a loop 1 or loop 2 parameter

350

, you must initiate a load/entry sequence.

Chapter 3

Programming

Algorithm Flow Chart

The algorithm flow chart shows the selectable features of the PID module’s control algorithms and indicates how selected features effect the entire algorithm.

The algorithm flow chart can be used as a road map when programming the PID module. Begin at the analog input. Select the needed features. Record their word and bit values on copies of the worksheet found in appendix A. When all needed features have been selected and the flow chart has been followed to completion, the selections can be entered into appropriate files in the PC processor. Data entry can be done after data table addresses have been assigned to the data block and the ladder diagram program has been entered into memory.

Prior to following the flow chart, there are five decisions concerning module features which must be made. These decisions and their corresponding control bits are not on the chart.

1-loop or 2-loop operation, W01 B15 standard or expanded features, W01 B14 4-digit BCD or 12-bit binary data format for most analog terms, W01

B12 4-digit BCD or 12-bit binary data format for the set point, W01 B11 soft fault response for each loop W38(W59) B15,14,13

Block Transfer Programming

The algorithm flow chart is shown in Figure 3.15. Sheet 1 shows, callouts, abbreviations, and how to interpret the flow chart. See Appendix E for an enlarged fold-out of the flow chart.

This section describes how the PID module is programmed. It also describes how the status of the PID module can be continuously read by the PC processor without performing read block transfers. Programming techniques and strategies are explained in this section. Example program/applications are presented in appendicies B and C. The programming explanations pertain to the PLC-2/30 processor. Programs can be modified for other processors capable of block transfer (refer to chapter 1).

351

Chapter 3

Programming

WORD / BIT CALLOUTS

SMIN ABBREVIATION FOR MINIMUM SCALING VALUE +

9999

W31 (W51)

W19 B06

B/B

YES

RANGE OF VALUES

PID MODULE WORD NUMBER. LOOP 1 (LOOP 2)

BIT NUMBER. (LOOP 2 NUMBERS ARE IN PARENTHESIS.)

PREFIX M MEANS MULTIPLER BIT(S).

PREFIX S MEANS SIGN BIT.

PREFIX B/B REFERS TO BCD/BINARY FORMAT BIT.

LOGIC STATE 0

LOGIC STATE 1

SYMBOLS

Figure 3.15 Algorithm

FUNCTION

DECISION

WRITE BLOCK TRANSFER FROM PC PROCESSOR

READ BLOCK TRANSFER TO PC PROCESSOR

Flow Chart (3 sheets)

THE ALGORITHM FLOW CHART CONSISTS OF TWO PAGES WHICH FOLLOW ON SHEETS 2 AND 3. THEY ARE SHOWN BELOW IN ABBREVIATED FORM TO PRESENT THE GENERAL SIGNAL FLOW AND TO DEFINE THE SYMBOLS AND CALLOUTS USED THROUGHOUT. THE BOX AT THE UPPER LEFT DESCRIBES THE WORD/BIT CALLOUTS. THE BOX JUST BELOW DEFINES THE SYMBOLS.

THERE ARE FIVE FEATURES NOT SHOWN ON THE CHART THAT SHOULD BE SELECTED BEFOREHAND:

1. ONE OR TWO LOOP OPERATION W01 B15

2. STANDARD OR EXPANDED FEATURES W01 B14

3. FOURDIGIT BCD OR 12BIT BINARY FORMAT FOR SETPOINT, W01 B11

4. FOURDIGIT BCD OR 12BIT BINARY FORMAT FOR ANALOG VALUES, W01 B12

5. SOFT FAULT RESPONSE FOR EACH LOOP, W39 (W59) B15, B14, B13

THE ALGORITHM FLOW CHART CAN BE USED AS A ROAD MAP WHEN PROGRAMMING. BEGIN AT THE ANALOG INPUT AND FOLLOW THE CHART TO DETERMINE WHICH FEATURES SHOULD BE IMPLEMENTED.

LEGEND SHEET

DOUBLE LINE SYMBOLS MEAN EXPANDED FEATURES (SINGLE LINE MEANS STANDARD FEATURES)

GO-TO AND RECEIVE-FROM LABELS WITHIN AND BETWEEN PAGES

HARDWARE OUTPUTS AND INPUTS

SMIN +

9999

W31 (W51) MW19 B06 (MW39 B06) SW30 B04 (SW50 B04)

SHEET 2

START EXPANDED FEATURES

SHEET 3

ENTER

MAX/MIN VALUES

START

FEEDFORWARD INPUT W10 (W17) B/B W01 B12

ENTER TIEBACK

PID

ANALOG INPUT

YES

TIEBACK

ERROR

YES

READ PV

SCALE

FFI OR

EXPAND

LOOP

ENTER BIAS

EXPAND

LOOP

BIAS

W08 (W15)

A/D

STANDARD FEATURES

SPV

PID

ANALOG OUTPUT

TIEBACK

INPUT

11118

352

START

HARDWARE ANALOG INPUT

S MAX

9999

W32 (W52)

MW19 B06 (MW39 B06) S W30 B03 (S W50 B03)

A/D

LOSS OF INPUT W61 B07 (W68 B07)

S MIN

9999

W31 (W51)

MW19 B06 (MW39 B06) SW30 B04 (SW50 B04)

ANALOG INPUT 4095 B/B W01 B12 W64 (W71)

ENTER MIN

AND MAX SCALING

VALUES

W18 B15 (W38 B15)

USE PV

FROM PC

PROCESSOR

USE VALUE

FROM PC

YES

PC PV 4095 B/B W01 B12 W09 (W16)

YES

W18 B14 (W38 B14)

PERFORM

(NORMALIZED)

W30 B17 (W50 B17)

SCALING

YES

(EXPANDED)

(EXP)

W01 B14

EXPANDED

LOOP

SELECTED

READ PV W65 (W72) SW61 B16 (SW68 B16)

DIGITAL FILTER

99.99 W20 (W40) MW19 B12 (MW39 B12) TA 0 MEANS OFF

SP +

9999

W06 (W13) MW19 B06 (MW39 B06) SW19 B07 (SW19 B07)

NO (STANDARD)

YES

TO DERIVATIVE

FUNCTION SHEET 2

Chapter 3

Programming

W30 B16 (W50 B16)

YES

(EXPANDED)

SCALING

SP 4095 B/B W01 B11 W06 (W13)

CASCADE

LOOP 2 ONLY ENABLED BY W30 B00

(+)

(-)

E = SP - PV

W01 B14

EXPANDED

LOOP

SELECTED

FROM CASCADE SHEET 3

CASCADE LOOP 1 TO LOOP 2

LOOP VALUE ENTERS HERE

CHANGE

E=PV-SP ?

NO (STANDARD)

E<EMN W61 B15 (W68 B15)

X(-1)

YES

W18 B13 (W38 B13)

E>EMP W61 B14 (W68 B14)

E=PV-SP

E=SP-PV

EMN W21 (W41) 4095

EMP W22 (W42) 4095

IF E<EMN THEN E=EMN

IF E>EMP THEN E=EMP

YES

ERROR

LIMIT

W18 B12 (W38 B12)

W61 B11 (W68 B11)

EXPANDED

LOOP

FEATURES

(STANDARD)

YES

(EXP)

W18 B11 (W38 B11)

IF E

THEN E = 0

ERROR

SCALING

YES

USE FUNCTION

ERROR

9999

W62 (W69) SW61 B17 (SW68 B17)

DEAD BAND

YES

ZERO CROSSING

DEAD BAND 4095 W23 (W43)

W18 B07 B06 (W38 B07 B06)

CHOOSE

ERROR

FUNCTION

CHOOSE

ERROR

FUNCTION

W18 B03 (W38 B03)

CHOOSE

ERROR OR PV

USE PV

FROM PV SHEET 2

YES

99.99 W07 (W14) MW19 B05 B04 (MW39 B05 B04)

DERIVATION

FUNCTION

PROPORTIONAL

FUNCTION

Kp ( )

I V1 1

MAX

W61 B10 (W68 B10)

I VP I > 4095 HOLD LAST W61 B03 (W68 B03)

INTEGRAL FUNCTION

> k1 ( )

IF K1=0 TERM SET TO 0

9.999 W24 (W44) MW19 B03 B02 (MW39 B03 B02)

( )

I VD 1 > VD

MAX

THEN I VD I = VD MAX

W61 B02 (W68 B02)

99.99 W25 (W45) MW19 B01 B00 (MW39 B01 B00)

I V1 1 THEN I V1 I = V1

MAX

BUMPLESS TRANSFER AND HOLDS ARE PERFORMED HERE

LIMIT

VD MAX

YES

I VD I > VD MAX

VD MAX W27 (W47)

V1 MAX W26 (W46)

V1 MAX

LIMIT

VD MAX

YES

NO NO

W18 B10 (W38 B10)

PID = V

+ V

PERFORM BUMPLESS TRANSFER

VALUE

HOLD

PID

+ V

YES

W18 B01 (W38 B01)

SEND LOOP1

VALUE TO LOOP 2

YES

DECOUPLE LOOP 1 TO

LOOP 2

LOOP 1 ONLY. ENABLED

11119

TO SHEET 3 DECOUPLE V

PID

BY W30

B14

PID

SHEET

353

Chapter 3

Programming

START EXPANDED FEATURES

SET FEEDFORWARD INPUT W10 (W17) 4095 B/ B 12

W30 B13 (W50 B13)

PC FFI

TIEBACK

YES

VALUE FROM

TIEBACK

INPUT

FROM SHEET 3

BIAS (FFV)

(FROM PC)

LOOP2

ONLY. ENABLED BY W30

DECOUPLE

YES

IF DECOUPLING WAS SELECTED VALUE IS INPUT HERE

DECOUPLE

PID

FROM SHEET 2

B14

W30 B11 (W50 B11)

FFI

YES YES

PERFORM

SQUARE

ROOT

(NORMALIZED)

W18 B00 (W38 B00)

HOLD LAST

HOLD BIAS (FFV)

YES

BIAS (FFV)

W30 B12 (W50 B12)

CHANGE

SIGN

X(-1)

YES

(EXPANDED)

FFI

FEEDFORWARD OFFSET (FF0) 9999 W33 (W53)

W01 B14

EXPANDED

LOOP

SELECTED

NO (STANDARD)

ENTER

BIAS

(BIAS ENTRY

STANDARD LOOP)

FFI+FF0

99.99 W34 (W54) MW30 B07, 06 (MW50 B07, 06)

W30 B10 (W50 B10)

BIAS 9999 W08 (W15)

X (K )

X K

STANDARD FEATURES

YES

W30 B05 (W50 B05)

K (FF0 + FFI)

PERFORM LEAD-LAG

99.99 W35 (W55) MW19 B11 (MW39 B11)

TCS +1

TB=0 TC=0 MEANS OFF

THE PATH TO THIS POINT HAS MEANING ONLY WHEN EXPANDED FEATURES ARE SELECTED

READ FEEDFORWARD VALUE .9999 W67 (W74) (SW68 B13) SW61B13

YES

99.99 W36 (W66) MW19 B10 (MW39 B10)

W30 B02 (W50 B02)

FFV

PC BIAS

YES

SET THRU

BIAS 9999 W08 (W15) BIAS ENTRY

(EXPANDED LOOP)

W30 B01 (W50 B01)

CHANGE

SIGN

YES

NO (FFV)

X(-1)

FROM SHEET

1: V=(V ) (BIAS)

0: V=V + BIAS

LOOP 2

W19 B16 (W39 B16)

PID

4095

PID

+/X

W19 B17 (W39 B17)

V < V MIN W61 B01 (W68 B01)

IF V V MIN, SET

V=V MIN

IF V

V > V MAX W61 B00 (W68 B00)

V MAX, SET V=V MAX

OUTPUT

LIMIT

V MAX

4095 W29

(W49)

YES

V MIN 4095 W28 (W48)

ONLY. ENABLED BY W30 B00

CASCADE

SEND VALUE OF LOOP 1

TO SP OF

LOOP 2

TO CASCADE

SHEET 2

YES

TO FEEDFORWARD LW30 B13 (W50 B13) SHEET 3

ANALOG TIEBACK INPUT

4095 B / B W01 B12 VALUE W66 (W73)

READ V W63 (W70) 4095 B / B W01 B12

W01 B01 (LOOP 1) W01 B02 (LOOP 2)

SET

DIRECT

BUMPLESS

YES

TRANSFER

SET ANALOG

OUTPUT

FROM PC

VALUE

SET ANALOG OUTPUT 4095 B/B W01 B12 W05 (W12)

W61 B05 (LOOP 1) W68 B05 (LOOP 2)

LOSS OF TIEBACK INPUT W61 B06 (W68 B06)

D / A

MANUAL

REQUEST

W01 B00

(ONE SHOT)

HARDWARE

SET BY PID

A / D

FAULT

MODULE

HARDWARE

ANALOG OUTPUT

MAN/AUTO

TIEBACK ANALOG INPUT

MANUAL

REQUEST

SINGLE OUTPUT

AUTO/ MANUAL STATION

(OPTIONAL)

TO CONTROL

DEVICE

11120

354

Chapter 3

Programming

Block Transfer Instruction Overview

All programming data for the PID module must be contained in files residing in the PC processor’s data table. The files are block transferred to the PID module where they are stored and used to perform PID control. Figure 3.16 and Figure 3.17 present a brief summary of block format block transfer instructions and data table locations.

NOTE: For PLC-2 family processors, the address of the file to be transferred in the address of the first word in the file. The file address is stored in BCD in a storage word located 100 8 above the instruction’s data address. The number of words transferred must vary according to the number of words in any of the files. When the block length is set to the default value, the PID module will control the block length for each transfer. Otherwise, if a program is written that allows unequal block length other than default to be enabled in the same scan, incomplete data could be transferred.

Figure 3.16 Block

Format Block T

A block transfer instruction is programmed in the ladder diagram by deptressing the [BLOCK XFER] key followed by [1] (for a READ) or [0] (for a WRITE). The appropriate read or write block, as shown below will appear on the industrial terminal screen.

Numbers shown are default values. Numbers in shaded areas must be replaced by userentered values. The number of default address digits initially displayed, 3, 4, or 5 will depend on the size of the data table. Initially displayed default values are governed by the I/O rack configuration.

Data Address : First, possible address in accumulated value area of data table.

Module Address : Rack, module group, and slot number.

Block Length : Number of words to be transferred. (00 can be entered for default value or for 64 words)

File : Address of first word in the file. Storage location is 100

Enable Bit (EN) : Automatically entered from the module address. Set on when rung containing the

instruction is true.

Done Bit (DN) : Automatically entered from the module address. Remains on for 1 scan following

successful transfer.

ransfer Instructions

BLOCK XFER READ

DATA ADDR:

MODULE ADDR:

BLOCK LENGTH:

FILE:

BLOCK XFER WRITE

DATA ADDR:

MODULE ADDR:

BLOCK LENGTH:

FILE:

above the data address.

030

100

110 110

030

100

110 110

0130

110

010

110

11121

355

Chapter 3

Programming

Data Table

Figure 3.17 Example Data T

BLOCK LENGTHCODE

able Locations for Bidirectional Block T

010

013

Output image table low byte

040

Data Addresses contains the module address 130: rack 1, module group 3, slot 0.

041

Input image table low byte

113

R=Read bit W=Write bit

ransfer

Read Block Transfer

(Input Buffer)

Write Block Transfer

File

140

Storage locations of file addresses

141 233

By setting the block length to default, 00, the module will determine the number of words up to 64 to be read to the PC processor.

256 257

By setting the block length to default, 00, the module will determine the number of words up to 64 to be written from the PC processor to the module.

356

BLOCK TRANSFER READ

DATA ADDR:

MODULE ADDR:

BLOCK LENGTH:

FILE:

BLOCK TRANSFER WRITE

DATA ADDR:

MODULE ADDR:

BLOCK LENGTH:

FILE:

040

130

233 332

041

130

257 356

013

113

11122

356

Chapter 3

Programming

Those unfamiliar with block transfer programming techniques should read the explanation found in the programming and Operation Manual for the PC processor being used. It is important to under block transfer concepts before reading this section.

Block Transfer Sequencing

The PID module is designed to sequence the multiple block transfers required to program the module and actively communicate with the PC processor. The PID module can prompt a block transfer sequence by sending to the PC processor the data table address of the first word in the file to be transferred next in the sequence. A rung in the ladder diagram program is required to manipulate the file address in the write block transfer instruction.

The data table address of each of the three data blocks is written to the PID module in the dynamic block transfer. One word defines the starting address of each block:

W03 dynamic block start address W04 loop 1 block start address W11 loop 2 block start address

The PID module returns to the PC processor the data table address (next block start address) of the next block to be transferred. The address is the value in word W59 in the status block. Two rungs are required to perform the prompting (Figure 3.18). During normal operation rung A gets the value returned by the PID module in word W59 and puts it in the file address storage word of the write block transfer instruction. The user program automatically performs the next block transfer required in the sequence determined in this manner by the PID module.

Rung B is active only at power-up. If the module is in the power-up mode and is unprogrammed, it cannot automatically prompt a block transfer. Instead, the PID module returns the power-up bit W58 B13 = 1 to a data table storage bit such as 350/13. The power-up bit controls rung B. At power-up only, rung B forces the write block transfer instruction to transfer the dynamic block. The dynamic block contains the block start address for each of the three write blocks. After the PID module receives this transfer, it can control the sequencing with rung A.

357

Rockwell Automation 1771-PD User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

General

General

Hardware Description

Manual Control Station Interface

Input Power Supply Requirements

Installation Practices

Chassis Considerations

Internal Fusing

Keying

Module Specifications

General

Operational Overview

Word and Bit Definitions

Algorithm Flow Chart

Block Transfer Programming