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Siemens simatic S7-1200. Manual (2015) - page 4

Easy to communicate between devices

7.10 PtP, USS, and Modbus communication protocols

PtP over PROFIBUS or PROFINET

Version V4.1 of the S7-1200 CPU together with STEP 7 V13 SP1 extends the capability of

PtP to use a PROFINET or PROFIBUS distributed I/O rack to communicate to various

devices (RFID readers, GPS device, and others):

● PROFINET (Page 147): You connect the Ethernet interface of the S7-1200 CPU to a

PROFINET interface module. PtP communication modules in the rack with the interface

module can then provide serial communications to the PtP devices.

● PROFIBUS (Page 157): You insert a PROFIBUS communication module in the left side

of the rack with the S7-1200 CPU. You connect the PROFIBUS communication module

to a rack containing a PROFIBUS interface module. PtP communication modules in the

rack with the interface module can then provide serial communications to the PtP

devices.

For this reason, the S7-1200 supports two sets of PtP instructions:

● Legacy point-to-point instructions: These instructions existed prior to version V4.0 of the

S7-1200 and only work with serial communications using a CM 1241 communication

module or CB 1241 communication board.

● Point-to-point instructions (Page 185): These instructions provide all of the functionaity of

the legacy instructions, plus the ability to connect to PROFINET and PROFIBUS

distributed I/O. The point-to-point instructions allow you to configure the communications

between the PtP communication modules in the distributed I/O rack and the PtP devices.

Note

With version V4.1 of the S7-1200, you can use the point-to-point instructions for all types of

point-to-point communication: serial, serial over PROFINET, and serial over PROFIBUS.

STEP 7 provides the legacy point-to-point instructions only to support existing programs. The

legacy instructions still function, however, with V4.1 CPUs as well as V4.0 and earlier CPUs.

You do not have to convert prior programs from one set of instructions to the other.

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7.10 PtP, USS, and Modbus communication protocols

Calculating the time required for communicating with the drive

Communications with the drive are asynchronous to the CPU scan. The CPU typically

completes several scans before one drive communications transaction is completed.

The USS_Port_Scan interval is the time required for one drive transaction. The table below

shows the minimum USS_Port_Scan interval for each communication baud rate. Calling the

USS_Port_Scan function more frequently than the USS_Port_Scan interval will not increase

the number of transactions. The drive timeout interval is the amount of time that might be

taken for a transaction, if communications errors caused 3 tries to complete the transaction.

By default, the USS protocol library automatically does up to 2 retries on each transaction.

Table 7- 14 Calculating the time requirements

Baud rate

Calculated minimum USS_Port_Scan call

Drive message interval timeout per

Interval (milliseconds)

drive (milliseconds)

1200

790

2370

2400

405

1215

4800

212.5

638

9600

116.3

349

19200

68.2

205

38400

44.1

133

57600

36.1

109

115200

28.1

85

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7.10 PtP, USS, and Modbus communication protocols

7.10.5

Modbus instructions

The CPU supports Modbus communication over different networks:

●

Modbus RTU (Remote Terminal Unit) is a standard network communication protocol that

uses the RS232 or RS485 electrical connection for serial data transfer between Modbus

network devices. You can add PtP (Point to Point) network ports to a CPU with a RS232

or RS485 CM or a RS485 CB.

Modbus RTU uses a master/slave network where all communications are initiated by a

single Master device and slaves can only respond to a master’s request. The master

sends a request to one slave address and only that slave address responds to the

command.

●

Modbus TCP (Transmission Control Protocol) is a standard network communication

protocol that uses the PROFINET connector on the CPU for TCP/IP communication. No

additional communication hardware module is required.

Modbus TCP uses client-server connections as a Modbus communication path. Multiple

client-server connections may exist, in addition to the connection between STEP 7 and

the CPU. Mixed client and server connections are supported up to the maximum number

of connections allowed by the CPU. Each MB_SERVER connection must use a unique

instance DB and IP port number. Only 1 connection per IP port is supported. Each

MB_SERVER (with its unique instance DB and IP port) must be executed individually for

each connection.

WARNING

If an attacker can physically access your networks, the attacker can possibly read and

write data.

The TIA Portal, the CPU, and HMIs (except HMIs using GET/PUT) use secure

communication that protects against replay and "man-in-the-middle" attacks. Once

communication is enabled, the exchange of signed messages takes place in clear text

which allows an attacker to read data, but protects against unauthorized writing of data.

The TIA Portal, not the communication process, encrypts the data of know-how

protected blocks.

All other forms of communication (I/O exchange through PROFIBUS, PROFINET, AS-i,

or other I/O bus, GET/PUT, T-Block, and communication modules (CM)) have no

security features. You must protect these forms of communication by limiting physical

access. If an attacker can physically access your networks utilizing these forms of

communication, the attacker can possibly read and write data.

For security information and recommendations, please see our "Operational Guidelines

for Industrial Security" on the Service and Support site:

www.industry.siemens.com/topics/global/en/industrial-

security/Documents/operational_guidelines_industrial_security_en.pdf

(http://www.industry.siemens.com/topics/global/en/industrial-

security/Documents/operational_guidelines_industrial_security_en.pdf)

Note

Modbus TCP will only operate correctly with CPU firmware release V1.02 or later. An

attempt to execute the Modbus instructions on an earlier firmware version will result in an

error.

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7.10 PtP, USS, and Modbus communication protocols

Table 7- 15 Modbus instructions

Type of communication

Instruction

Modbus RTU (RS232 or RS485)

Modbus_Comm_Load: One execution of Modbus_Comm_Load is used to set up PtP

port parameters like baud rate, parity, and flow control. After the CPU port is config-

ured for the Modbus RTU protocol, it can only be used by either the Modbus_Master

or Modbus_Slave instructions.

Modbus_Master: The Modbus master instruction enables the CPU to act as a Mod-

bus RTU master device and communicate with one or more Modbus slave devices.

Modbus_Slave: The Modbus slave instruction enables the CPU to act as a Modbus

RTU slave device and communicate with a Modbus master device.

Modbus TCP (PROFINET)

MB_CLIENT: Make client-server TCP connection, send command message, receive

response, and control the disconnection from the server.

MB_SERVER: Connect to a Modbus TCP client upon request, receive Modbus mes-

sage, and send response.

The Modbus instructions do not use communication interrupt events to control the

communication process. Your program must poll the Modbus_Master / Modbus_Slave or

MB_CLIENT/ MB_SERVER instructions for transmit and receive complete conditions.

A Modbus TCP client (master) must control the client-server connection with the

DISCONNECT parameter. The basic Modbus client actions are shown below.

1. Initiate a connection to a particular server (slave) IP address and IP port number

2. Initiate client transmission of Modbus messages and receive the server responses

3. When required, initiate the disconnection of client and server to enable connection with a

different server.

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8

STEP 7 provides the following PID instructions for the S7-1200 CPU:

● The PID_Compact instruction is used to control technical processes with continuous

input- and output variables.

● The PID_3Step instruction is used to control motor-actuated devices, such as valves that

require discrete signals for open- and close actuation.

● The PID_Temp instruction provides a universal PID controller that allows handling of the

specific requirements of temperature control.

Note

Changes that you make to the PID configuration and download in RUN do not take effect

until the CPU transitions from STOP to RUN mode. Changes that you make in the "PID

parameters" dialog using the "Start value control" take effect immediately.

All three PID instructions (PID_Compact, PID_3Step, and PID_Temp) can calculate the P-, I-

, and D-components during startup (if configured for "pre-tuning"). You can also configure

the instruction for "fine tuning" to allow you to optimize the parameters. You do not need to

manually determine the parameters.

Note

Execute the PID instruction at constant intervals of the sampling time (preferably in a cyclic

OB).

Because the PID loop needs a certain time to respond to changes of the control value, do

not calculate the output value in every cycle. Do not execute the PID instruction in the main

program cycle OB (such as OB 1).

The sampling time of the PID algorithm represents the time between two calculations of the

output value (control value). The output value is calculated during self-tuning and rounded to

a multiple of the cycle time. All other functions of PID instruction are executed at every call.

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PID algorithm

The PID (Proportional/Integral/Derivative) controller measures the time interval between two

calls and then evaluates the results for monitoring the sampling time. A mean value of the

sampling time is generated at each mode changeover and during initial startup. This value is

used as reference for the monitoring function and is used for calculation. Monitoring includes

the current measuring time between two calls and the mean value of the defined controller

sampling time.

The output value for the PID controller consists of three components:

● P (proportional): When calculated with the "P" component, the output value is proportional

to the difference between the setpoint and the process value (input value).

● I (integral): When calculated with the "I" component, the output value increases in

proportion to the duration of the difference between the setpoint and the process value

(input value) to finally correct the difference.

● D (derivative): When calculated with the "D" component, the output value increases as a

function of the increasing rate of change of the difference between the setpoint and the

process value (input value). The output value is corrected to the setpoint as quickly as

possible.

The PID controller uses the following formula to calculate the output value for the

PID_Compact instruction.

y

Output value

x

Process value

w Setpoint value

s

Laplace operator

Kp

Proportional gain

a

Derivative delay coefficient

(P component)

(D component)

T1

Integral action time

b

Proportional action weighting

(I component)

(P component)

TD

Derivative action time

c

Derivative action weighting

(D component)

(D component)

The PID controller uses the following formula to calculate the output value for the PID_3Step

instruction.

y

Output value

x

Process value

w Setpoint value

s

Laplace operator

Kp

Proportional gain

a

Derivative delay coefficient

(P component)

(D component)

T1

Integral action time

b

Proportional action weighting

(I component)

(P component)

TD

Derivative action time

c

Derivative action weighting

(D component)

(D component)

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8.1 Inserting the PID instruction and technology object

8.1

Inserting the PID instruction and technology object

STEP 7 provides two instructions for PID control:

● The PID_Compact instruction and its associated technology object provide a universal

PID controller with tuning. The technology object contains all of the settings for the control

loop.

● The PID_3Step instruction and its associated technology object provide a PID controller

with specific settings for motor-activated valves. The technology object contains all of the

settings for the control loop. The PID_3Step controller provides two additional Boolean

outputs.

After creating the technology object, you must configure the parameters (Page 222). You

also adjust the autotuning parameters ("pre-tuning" during startup or manual "fine tuning") to

commission the operation of the PID controller (Page 239).

Table 8- 1

Inserting the PID instruction and the technology object

When you insert a PID instruction into your user program,

STEP 7 automatically creates a technology object and an

instance DB for the instruction. The instance DB contains

all of the parameters that are used by the PID instruction.

Each PID instruction must have its own unique instance

DB to operate properly.

After inserting the PID instruction and creating the tech-

nology object and instance DB, you configure the parame-

ters for the technology object (Page 222).

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8.1 Inserting the PID instruction and technology object

Table 8- 2

(Optional) Creating a technology object from the project navigator

You can also create technology objects for your

project before inserting the PID instruction. By

creating the technology object before inserting a

PID instruction into your user program, you can

then select the technology object when you insert

the PID instruction.

To create a technology object, double-click the

"Add new object" icon in the project navigator.

Click the "Control" icon and select the technology

object for the type of PID controller (PID_Compact

or PID_3Step). You can create an optional name

for the technology object.

Click "OK" to create the technology object.

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8.2 PID_Compact instruction

8.2

PID_Compact instruction

The PID_Compact instruction provides a universal PID controller with integrated self-tuning

for automatic and manual mode.

Table 8- 3

PID_Compact instruction

LAD / FBD

SCL

Description

"PID_Compact_1"(

PID_Compact provides a PID controller with

Setpoint:=_real_in_,

self-tuning for automatic and manual mode.

Input:=_real_in_,

PID_Compact is a PID T1 controller with

Input_PER:=_word_in_,

anti-windup and weighting of the P- and D-

component.

Disturbance:=_real_in_,

ManualEnable:=_bool_in_,

ManualValue:=_real_in_,

ErrorAck:=_bool_in_,

Reset:=_bool_in_,

ModeActivate:=_bool_in_,

Mode:=_int_in_,

ScaledInput=>_real_out_,

Output=>_real_out_,

Output_PER=>_word_out_,

Output_PWM=>_bool_out_,

SetpointLimit_H=>_bool_out_,

SetpointLimit_L=>_bool_out_,

InputWarn-

ing_H=>_bool_out_,

InputWarn-

ing_L=>_bool_out_,

State=>_int_out_,

Error=>_bool_out_,

ErrorBits=>_dword_out_);

1

STEP 7 automatically creates the technology object and instance DB when you insert the instruction. The instance DB

contains the parameters of the technology object.

2

In the SCL example, "PID_Compact_1" is the name of the instance DB.

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8.2 PID_Compact instruction

Table 8- 4

Data types for the parameters

Parameter and type

Data type

Description

Setpoint

IN

Real

Setpoint of the PID controller in automatic mode. (Default value: 0.0)

Input

IN

Real

A tag of the user program is used as the source of the process value.

(Default value: 0.0)

If you are using the Input parameter, you must set Con-

fig.InputPerOn = FALSE.

Input_PER

IN

Word

An Analog input is used as the source of the process value. (Default

value: W#16#0)

If you are using the Input_PER parameter, you must set Con-

fig.InputPerOn = TRUE.

Disturbance

IN

Real

Disturbance variable or pre-control value

ManualEnable

IN

Bool

Enables or disables the manual operation mode. (Default value:

FALSE):

• A FALSE to TRUE edge activates "manual mode", while State = 4,

Mode remains unchanged.

As long as ManualEnable = TRUE, you cannot change the operat-

ing mode using a rising edge at ModeActivate or use the commis-

sioning dialog.

• A TRUE to FALSE edge activates the operating mode that is as-

signed by Mode.

Note: We recommend that you change the operating mode using

ModeActivate only.

ManualValue

IN

Real

Output value for manual operation. (Default value: 0.0)

You can use values from Config.OutputLowerLimit to Con-

fig.OutputUpperLimit.

ErrorAck

IN

Bool

Resets the ErrorBits and warning outputs. FALSE to TRUE edge

Reset

IN

Bool

Restarts the controller. (Default value: FALSE):

• FALSE to TRUE edge:

- Switches to "inactive" mode

- Resets the ErrorBits and warning outputs

- Clears Integral action

- Maintains PID parameters

• As long as Reset = TRUE, PID_Compact remains in "Inactive"

mode (State = 0).

• TRUE to FALSE edge:

- PID_Compact switches to the operating mode that is saved in

the Mode parameter.

ModeActivate

IN

Bool

The PID_Compact switches to the operating mode that is saved in the

Mode parameter. FALSE to TRUE edge:

Mode

IN

Int

The desired PID mode; Activated on the leading edge of the Mode

Activate input.

ScaledInput

OUT

Real

Scaled process value. (Default value: 0.0)

Output¹

OUT

Real

Output value in REAL format. (Default value: 0.0)

Output_PER¹

OUT

Word

Analog output value. (Default value: W#16#0)

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8.2 PID_Compact instruction

Parameter and type

Data type

Description

Output_PWM¹

OUT

Bool

Output value for pulse width modulation. (Default value: FALSE)

On and Off times form the output value.

SetpointLimit_H

OUT

Bool

Setpoint high limit. (Default value: FALSE)

If SetpointLimit_H = TRUE, the absolute setpoint upper limit is reached

(Setpoint ≥ Config.SetpointUpperLimit).

The setpoint is limited to Config.SetpointUpperLimit.

SetpointLimit_L

OUT

Bool

Setpoint low limit. (Default value: FALSE)

If SetpointLimit_L = TRUE, the absolute setpoint lower limit is reached

(Setpoint ≤ Config.SetpointLowerLimit).

The setpoint is limited to Config.SetpointLowerLimit.

InputWarning_H

OUT

Bool

If InputWarning_H = TRUE, the process value has reached or exceed-

ed the warning high limit. (Default value: FALSE)

InputWarning_L

OUT

Bool

If InputWarning_L = TRUE, the process value has reached or fallen

below the warning low limit. (Default value: FALSE)

State

OUT

Int

Current operating mode of the PID controller. (Default value: 0)

You can change the operating mode using the Mode input parameter

and a rising edge at ModeActivate:

• State = 0: Inactive

• State = 1: Pre-tuning

• State = 2: Manual fine tuning

• State = 3: Automatic mode

• State = 4: Manual mode

• State = 5: Substitute output value with error monitoring

Error

OUT

Bool

If Error = TRUE, at least one error message is pending in this cycle.

(Default value: FALSE)

Note: The Error parameter in V1.x PID was the ErrorBits field that con-

tained the error codes. It is now a Boolean flag indicating that an error

has occurred.

ErrorBits

OUT

DWord

The PID_Compact instruction ErrorBits parameters table (Page 199)

defines the error messages that are pending. (Default value:

DW#16#0000 (no error)). ErrorBits is retentive and is reset upon a

rising edge at Reset or ErrorAck.

Note: In V1.x, the ErrorBits parameter was defined as the Error param-

eter and did not exist.

1

You can use the outputs of the Output, Output_PER, and Output_PWM parameters in parallel.

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8.2 PID_Compact instruction

Operation of the PID_Compact controller

Figure 8-1

Operation of the PID_Compact controller

Figure 8-2

Operation of the PID_Compact controller as a PIDT1 controller with anti-windup

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8.3 PID_Compact instruction ErrorBit parameters

8.3

PID_Compact instruction ErrorBit parameters

If several errors are pending, the values of the error codes are displayed by means of binary

addition. The display of error code 0003, for example, indicates that the errors 0001 and

0002 are also pending.

Table 8- 5

PID_Compact instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

0000

No error

0001 ^{1, 2}

The Input parameter is outside the process value limits.

Input > Config.InputUpperLimit

Input < Config.InputLowerLimit

0002 ^{2, 3}

Invalid value at the Input_PER parameter. Check whether an error is pend-

ing at the analog input.

0004 ⁴

Error during fine tuning. Oscillation of the process value could not be main-

tained.

0008 ⁴

Error at start of pre-tuning. The process value is too close to the setpoint.

Start fine tuning.

0010 ⁴

The setpoint was changed during tuning.

Note: You can set the permitted fluctuation on the setpoint at the Cancel-

TuningLevel tag.

0020

Pre-tuning is not permitted during fine tuning.

Note: If ActivateRecoverMode = TRUE before the error occurred,

PID_Compact remains in fine tuning mode.

0080 ⁴

Error during pre-tuning. Incorrect configuration of output value limits.

Check whether the limits of the output value are configured correctly and

match the control logic.

0100 ⁴

Error during fine tuning resulted in invalid parameters.

0200 ^{2, 3}

Invalid value at the Input parameter: Value has an invalid number format.

0400 ^{2, 3}

Calculation of the output value failed. Check the PID parameters.

0800 ^{1, 2}

Sampling time error: PID_Compact is not called within the sampling time of

the cyclic interrupt OB.

1000 ^{2, 3}

Invalid value at the Setpoint parameter: Value has an invalid number format.

10000

Invalid value at the ManualValue parameter: Value has an invalid number

format.

Note: If ActivateRecoverMode = TRUE before the error occurred,

PID_Compact uses SubstituteOutput as the output value. As soon as you

assign a valid value in the ManualValue parameter, PID_Compact uses it as

the output value.

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8.3 PID_Compact instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

20000

Invalid value at the SubstituteValue tag: Value has an invalid number for-

mat.

PID_Compact uses the output value low limit as the output value.

Note: If automatic mode was active before the error occurred, Acti-

vateRecoverMode = TRUE, and the error is no longer pending,

PID_Compact switches back to automatic mode.

40000

Invalid value at the Disturbance parameter: Value has an invalid number

format.

Note: If automatic mode was active and ActivateRecoverMode = FALSE

before the error occurred, Disturbance is set to zero. PID_Compact remains

in automatic mode.

Note: If pre-tuning or fine tuning mode was active and ActivateRecoverMode

= TRUE before the error occurred, PID_Compact switches to the operating

mode that is saved in the Mode parameter. If Disturbance in the current

phase has no effect on the output value, tuning is not canceled.

1

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,

PID_Compact remains in automatic mode.

2

Note: If pre-tuning or fine tuning mode was active before the error occurred and ActivateRecover-

Mode = TRUE, PID_Compact switches to the operating mode that is saved in the

Mode parameter.

3

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,

PID_Compact outputs the configured substitute output value. As soon as the error is no longer

pending, PID_Compact switches back to automatic mode.

4

Note: If ActivateRecoverMode = TRUE before the error occurred, PID_Compact cancels the tuning

and switches to the operating mode that is saved in the Mode parameter.

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8.4 PID_3Step instruction

8.4

PID_3Step instruction

The PID_3Step instruction configures a PID controller with self-tuning capabilities that has

been optimized for motor-controlled valves and actuators.

Table 8- 6

PID_3Step instruction

LAD / FBD

SCL

Description

"PID_3Step_1"(

PID_3Step configures a PID controller with

SetpoInt:=_real_in_,

self-tuning capabilities that has been opti-

Input:=_real_in_,

mized for motor-controlled valves and

ManualValue:=_real_in_,

actuators. It provides two Boolean outputs.

Feedback:=_real_in_,

PID_3Step is a PID T1controller with anti-

InputPer:=_word_in_,

windup and weighting of the P- and D-

FeedbackPer:=_word_in_,

components.

Disturbance:=_real_in_,

ManualEnable:=_bool_in_,

ManualUP:=_bool_in_,

ManualDN:=_bool_in_,

ActuatorH:=_bool_in_,

ActuatorL:=_bool_in_,

ErrorAck:=_bool_in_,

Reset:=_bool_in_,

ModeActivate:=_bool_in_,

Mode:=_int_in_,

ScaledInput=>_real_out_,

ScaledFeedback=>_real_out_,

ErrorBits=>_dword_out_,

OutputPer=>_word_out_,

State=>_int_out_,

OutputUP=>_bool_out_,

OutputDN=>_bool_out_,

SetpoIntLimitH=>_bool_out_,

SetpoIntLimitL=>_bool_out_,

InputWarningH=>_bool_out_,

InputWarningL=>_bool_out_,

Error=>_bool_out_,

ErrorBits=>_dword_out_);

1

STEP 7 automatically creates the technology object and instance DB when you insert the instruction. The instance DB

contains the parameters of the technology object.

2

In the SCL example, "PID_3Step_1" is the name of the instance DB.

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8.4 PID_3Step instruction

Table 8- 7

Data types for the parameters

Parameter and type

Data type

Description

Setpoint

IN

Real

Setpoint of the PID controller in automatic mode. (Default value: 0.0)

Input

IN

Real

A tag of the user program is used as the source of the process value.

(Default value: 0.0)

If you are using the Input parameter, you must set Con-

fig.InputPerOn = FALSE.

Input_PER

IN

Word

An Analog input is used as the source of the process value. (Default

value: W#16#0)

If you are using the Input_PER parameter, you must set Con-

fig.InputPerOn = TRUE.

Actuator_H

IN

Bool

Digital position feedback of the valve for the high end stop

If Actuator_H = TRUE, the valve is at the high end stop and is no longer

moved in this direction. (Default value: FALSE)

Actuator_L

IN

Bool

Digital position feedback of the valve for the low end stop

If Actuator_L = TRUE, the valve is at the low end stop and is no longer

moved in this direction. (Default value: FALSE)

Feedback

IN

Real

Position feedback of the valve. (Default value: 0.0)

If you are using the Feedback parameter, you must set Con-

fig.FeedbackPerOn = FALSE.

Feedback_PER

IN

Int

Analog feedback of the valve position. (Default value: W#16#0)

If you are using the Feedback_PER parameter, you must set Con-

fig.FeedbackPerOn = TRUE. Feedback_PER is scaled, based upon the

following tags:

• Config.FeedbackScaling.LowerPointIn

• Config.FeedbackScaling.UpperPointIn

• Config.FeedbackScaling.LowerPointOut

• Config.FeedbackScaling.UpperPointOut

Disturbance

IN

Real

Disturbance variable or pre-control value

ManualEnable

IN

Bool

Enables or disables the manual operation mode. (Default value:

FALSE):

• A FALSE to TRUE edge activates "manual mode", while State = 4,

Mode remains unchanged.

As long as ManualEnable = TRUE, you cannot change the operat-

ing mode using a rising edge at ModeActivate or use the commis-

sioning dialog.

• A TRUE to FALSE edge activates the operating mode that is as-

signed by Mode.

Note: We recommend that you change the operating mode using

ModeActivate only.

ManualValue

IN

Real

Process value for manual operation. (Default value: 0.0)

In manual mode, you specify the absolute position of the valve. Manu-

alValue is evaluated only if you are using OutputPer, or if position feed-

back is available.

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8.4 PID_3Step instruction

Parameter and type

Data type

Description

ManualUP

IN

Bool

• Manual_UP = TRUE:

- The valve is opened even if you use Output_PER or a position

feedback. The valve is no longer moved if the high end stop has

been reached.

- See also Config.VirtualActuatorLimit

• Manual_UP = FALSE:

- If you use Output_PER or a position feedback, the valve is

moved to ManualValue. Otherwise, the valve is no longer

moved.

Note: If Manual_UP and Manual_DN are set to TRUE simultaneously,

the valve is not moved.

ManualDN

IN

Bool

• Manual_DN = TRUE:

- The valve is opened even if you use Output_PER or a position

feedback. The valve is no longer moved if the high end stop has

been reached.

- See also Config.VirtualActuatorLimit

• Manual_DN = FALSE:

- If you use Output_PER or a position feedback, the valve is

moved to ManualValue. Otherwise, the valve is no longer

moved.

ErrorAck

IN

Bool

Resets the ErrorBits and warning outputs. FALSE to TRUE edge

Reset

IN

Bool

Restarts the controller. (Default value: FALSE):

• FALSE to TRUE edge:

- Switches to "inactive" mode

- Resets the ErrorBits and warning outputs

- Clears Integral action

- Maintains PID parameters

• As long as Reset = TRUE, PID_3Step remains in "Inactive" mode

(State = 0).

• TRUE to FALSE edge:

- PID_3Step switches to the operating mode that is saved in the

Mode parameter.

ModeActivate

IN

Bool

The PID_3Step switches to the mode that is saved in the Mode param-

eter. FALSE to TRUE edge:

Mode

IN

Int

The desired PID mode; Activated on the leading edge of the Mode

Activate input.

ScaledInput

OUT

Real

Scaled process value

ScaledFeedback

OUT

Real

Scaled valve position feedback

Note: For an actuator without position feedback, the position of the

actuator indicated by ScaledFeedback is very imprecise. ScaledFeed-

back can only be used for rough estimation of the current position in

this case.

Output_UP

OUT

Bool

Digital output value for opening the valve. (Default value: FALSE)

If Config.OutputPerOn = FALSE, the parameter Output_UP is used.

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8.4 PID_3Step instruction

Parameter and type

Data type

Description

Output_DN

OUT

Bool

Digital output value for closing the valve. (Default value: FALSE)

If Config.OutputPerOn = FALSE, the parameter Output_DN is used.

Output_PER

OUT

Word

Analog output value.

If Config.OutputPerOn = TRUE, the parameter Output_PER is used.

SetpointLimitH

OUT

Bool

Setpoint high limit. (Default value: FALSE)

If SetpointLimitH = TRUE, the absolute upper limit of the setpoint is

reached (Setpoint ≥ Config.SetpointUpperLimit).

Note: The setpoint is limited to (Setpoint ≥ Config.SetpointUpperLimit).

SetpointLimitL

OUT

Bool

Setpoint low limit. (Default value: FALSE)

If SetpointLimitL = TRUE, the absolute lower limit of the setpoint is

reached (Setpoint ≥ Config.SetpointLowerLimit).

Note: The setpoint is limited to (Setpoint ≥ Config.SetpointLowerLimit).

InputWarningH

OUT

Bool

If InputWarningH = TRUE, the input value has reached or exceeded the

warning high limit. (Default value: FALSE)

InputWarningL

OUT

Bool

If InputWarningL = TRUE, the input value has reached or exceeded the

warning low limit. (Default value: FALSE)

State

OUT

Int

Current operating mode of the PID controller. (Default value: 0)

You can change the operating mode using the Mode input parameter

and a rising edge at ModeActivate:

• State = 0: Inactive

• State = 1: Pre-tuning

• State = 2: Manual fine tuning

• State = 3: Automatic mode

• State = 4: Manual mode

• State = 5: Substitute output value approach

• State = 6: Transition time measurement

• State = 7: Error monitoring

• State = 8: Substitute output value approach with error monitoring\

• State = 10: Manual mode without end stop signals

Error

OUT

Bool

If Error = TRUE, at least one error message is pending. (Default value:

FALSE)

Note: The Error parameter in V1.x PID was the ErrorBits field that con-

tained the error codes. It is now a Boolean flag indicating that an error

has occurred.

ErrorBits

OUT

DWord

The PID_3Step instruction ErrorBits parameters table (Page 208) de-

fines the error messages that are pending. (Default value:

DW#16#0000 (no error)). ErrorBits is retentive and is reset upon a

rising edge at Reset or ErrorAck.

Note: In V1.x, the ErrorBits parameter was defined as the Error param-

eter and did not exist.

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8.4 PID_3Step instruction

Operation of the PID_3Step controller

Figure 8-3

Operation of the PID_3Step controller as a PID T1 controller with anti-windup

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8.4 PID_3Step instruction

Figure 8-4

Operation of the PID_3Step controller without position feedback

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8.4 PID_3Step instruction

Figure 8-5

Operation of the PID_3Step controller with position feedback enabled

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8.5 PID_3Step instruction ErrorBit parameters

8.5

PID_3Step instruction ErrorBit parameters

If several errors are pending, the values of the error codes are displayed by means of binary

addition. The display of error code 0003, for example, indicates that the errors 0001 and

0002 are also pending.

Table 8- 8

PID_3STEP instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

0000

No error

0001 ^{1, 2}

The Input parameter is outside the process value limits.

Input > Config.InputUpperLimit

Input < Config.InputLowerLimit

0002 ^{2, 3}

Invalid value at the Input_PER parameter. Check whether an error is pend-

ing at the analog input.

0004 ⁴

Error during fine tuning. Oscillation of the process value could not be main-

tained.

0010 ⁴

The setpoint was changed during tuning.

Note: You can set the permitted fluctuation on the setpoint at the Cancel-

TuningLevel tag.

0020

Pre-tuning is not permitted during fine tuning.

Note: If ActivateRecoverMode = TRUE before the error occurred, PID_3Step

remains in fine tuning mode.

0080 ⁴

Error during pre-tuning. Incorrect configuration of output value limits.

Check whether the limits of the output value are configured correctly and

match the control logic.

0100 ⁴

Error during fine tuning resulted in invalid parameters.

0200 ^{2, 3}

Invalid value at the Input parameter: Value has an invalid number format.

0400 ^{2, 3}

Calculating the output value failed. Check the PID parameters.

0800 ^{1, 2}

Sampling time error: PID_3Step is not called within the sampling time of the

cyclic interrupt OB.

1000 ^{2, 3}

Invalid value at the Setpoint parameter: Value has an invalid number format.

2000 ^{1, 2, 5}

Invalid value at the Feedback_PER parameter.

Check whether an error is pending at the analog input.

4000 ^{1, 2, 5}

Invalid value at the Feedback parameter: Value has an invalid number for-

mat.

8000 ^{1, 2}

Error during digital position feedback. Actuator_H = TRUE and Actuator_L =

TRUE.

The actuator cannot be moved to the substitute output value and remains in

its current position. Manual mode is not possible in this state.

In order to move the actuator from this state, you must deactivate the "Actu-

ator end stop" (Config.ActuatorEndStopOn = FALSE) or switch to manual

mode without end stop signals (Mode = 10).

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8.5 PID_3Step instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

10000

Invalid value at the ManualValue parameter: Value has an invalid number

format.

The actuator cannot be moved to the manual value and remains in its cur-

rent position.

Assign a valid value in ManualValue or move the actuator in manual mode

with Manual_UP and Manual_DN.

20000

Invalid value at the SavePosition tag: Value has an invalid number format.

The actuator cannot be moved to the substitute output value and remains in

its current position.

40000

Invalid value at the Disturbance parameter: Value has an invalid number

format.

Note: If automatic mode was active and ActivateRecoverMode = FALSE

before the error occurred, Disturbance is set to zero. PID_3Step remains in

automatic mode.

Note: If pre-tuning or fine tuning mode was active and ActivateRecoverMode

= TRUE before the error occurred, PID_3Step switches to the operating

mode that is saved in the Mode parameter. If Disturbance in the current

phase has no effect on the output value, tuning is not canceled.

The error has no effect during transition time measurement.

1

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,

PID_3Step remains in automatic mode.

2

Note: If pre-tuning, fine tuning, or transition time measurement mode were active and Acti-

vateRecoverMode = TRUE before the error occurred, PID_3Step switches to the operating mode

that is saved in the Mode parameter.

3

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,

PID_3Step switches to "Approach substitute output value with error monitoring" or "Error monitor-

ing" mode. As soon as the error is no longer pending, PID_3Step switches back to automatic

mode.

4

Note: If ActivateRecoverMode = TRUE before the error occurred, PID_3Step cancels the tuning

and switches to the operating mode that is saved in the Mode parameter.

5

The actuator cannot be moved to the substitute output value and remains in its current position. In

manual mode, you can change the position of the actuator only with Manual_UP and Manual_DN,

and not with ManualValue.

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8.6 PID_Temp instruction

8.6

PID_Temp instruction

8.6.1

Overview

The PID_Temp instruction provides a universal PID controller that allows handling of the

specific requirements of temperature control.

Table 8- 9

PID_Temp instruction

LAD / FBD

SCL

Description

"PID_Temp_1"(

PID_Temp provides these capabilities:

Setpoint:=_real_in_,

•

Heating and cooling of the process with

Input:=_real_in_,

different actuators

Input_PER:=_int_in_,

•

Integrated autotuning to handle temper-

Disturbance:=_real_in_,

ature processes

ManualEnable:=_bool_in_,

ManualValue:=_real_in_,

•

Cascading to process more than one

ErrorAck:=_bool_in_,

temperature that depends on the same

Reset:=_bool_in_,

actuator

ModeActivate:=_bool_in_,

Mode:=_int_in_,

Master:=_dword_in

Save:=_dword_in

ScaledInput=>_real_out_,

OutputHeat=>_real_out_,

OutputCool=>_real_out_,

OutputHeat_PER=>_int_out_,

OutputCool_PER=>_int_out_,

Out-

putHeat_PWM=>_bool_out_,

Out-

putCool_PWM=>_bool_out_,

SetpointLimit_H=>_bool_out_,

SetpointLimit_L=>_bool_out_,

InputWarn-

ing_H=>_bool_out_,

InputWarn-

ing_L=>_bool_out_,

State=>_int_out_,

Error=>_bool_out_,

ErrorBits=>_dword_out_);

1

STEP 7 automatically creates the technology object and instance DB when you insert the instruction. The instance DB

contains the parameters of the technology object.

2

In the SCL example, "PID_Temp_1" is the name of the instance DB.

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8.6 PID_Temp instruction

Table 8- 10 Data types for the parameters

Parameter and type

Data type

Description

Setpoint

IN

Real

Setpoint of the PID controller in automatic mode. (Default value: 0.0)

Input

IN

Real

A tag of the user program is used as the source of the process value.

(Default value: 0.0)

If you are using the Input parameter, you must set Con-

fig.InputPerOn = FALSE.

Input_PER

IN

Int

An Analog input is used as the source of the process value. (Default

value: 0)

If you are using the Input_PER parameter, you must set Con-

fig.InputPerOn = TRUE.

Disturbance

IN

Real

Disturbance variable or pre-control value

ManualEnable

IN

Bool

Enables or disables the manual operation mode. (Default value:

FALSE):

• A FALSE to TRUE edge activates Manual mode, while State = 4,

Mode remains unchanged.

As long as ManualEnable = TRUE, you cannot change the operat-

ing mode using a rising edge at ModeActivate or use the commis-

sioning dialog.

• A TRUE to FALSE edge activates the operating mode that is as-

signed by Mode.

Note: We recommend that you change the operating mode using

ModeActivate only.

ManualValue

IN

Real

Output value for manual operation. (Default value: 0.0)

You can use values from Config.OutputLowerLimit to Con-

fig.OutputUpperLimit.

ErrorAck

IN

Bool

Resets the ErrorBits and warning outputs with a FALSE to TRUE edge.

(Default value: FALSE)

Reset

IN

Bool

Restarts the controller. (Default value: FALSE):

• FALSE to TRUE edge:

- Switches to "inactive" mode

- Resets the ErrorBits and warning outputs

- Clears Integral action

- Maintains PID parameters

• As long as Reset = TRUE, PID_Temp remains in Inactive mode

(State = 0).

• TRUE to FALSE edge:

- PID_Temp switches to the operating mode that is saved in the

Mode parameter.

ModeActivate

IN

Bool

The PID_Temp switches to the operating mode that is saved in the

Mode parameter with a FALSE to TRUE edge. (Default value: FALSE)

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8.6 PID_Temp instruction

Parameter and type

Data type

Description

Mode

IN/OUT

Int

Activated on the leading edge of the Mode Activate input.

Operating mode selection (Default value: 0.0):

• Mode = 0: Inactive

• Mode = 1: Pretuning

• Mode = 2: Fine tuning

• Mode = 3: Automatic mode

• Mode = 4: Manual mode

“Substitute output value with error monitoring” (State = 5). This cannot

be activated by the user; it is only an automatic error reaction.

Master

IN/OUT

DWord

Cascade connection to master (AntiWindUp and tuning conditions).

(Default value: DW#16#0000)

Slave

IN/OUT

DWord

• Bits 0 - 15: Not used in PID_Temp instruction

• Bits 16 - 23: Limit counter: A slave increments this value if it reach-

es its limitation. The number of slaves in limitation is processed for

Anti-Windup-functionality (Refer to the Con-

fig.Cascade.AntiWindUpMode parameter.

• Bit 24: IsAutomatic: This bit is set to "1" if all slaves of this controller

are in Automatic mode and are processed to check conditions for

tuning in a cascade. This bit is identical to the AllSlaveAutomat-

icState parameter.

• Bit 25: "IsReplacement-Setpoint": This bit is set to "1" if a slave of

this controller has the "Replacement Setpoint" activated and is pro-

cessed to check conditions for tuning in a cascade. The inverted

value is stored in the NoSlaveReplacementSetpoint parameter.

ScaledInput

OUT

Real

Scaled process value. (Default value: 0.0)

OutputHeat¹

OUT

Real

Output value for heating in REAL format. (Default value: 0.0)

This output value is calculated, independent from the output selection,

using the Config.Output.Heat.Select parameter.

OutputCool¹

OUT

Real

Output value for cooling in REAL format. (Default value: 0.0)

This output value is calculated, independent from the output selection,

using the Config.Output.Cool.Select parameter.

OutputHeat_PER

1

OUT

Int

Output value for heating in peripheral format (Default value: 0)

This output value is only calculated if selected using the Con-

fig.Output.Heat.Select = 2 parameter. If not selected, this output is

always "0".

OutputCool_PER¹

OUT

Int

Output value for cooling in peripheral format (Default value: 0)

This output value is only calculated if selected using the Con-

fig.Output.Cool.Select = 2 parameter. If not selected, this output is

always "0".

OutputHeat_PWM¹

OUT

Bool

Pulse-width-modulated output value for heating. (Default value: FALSE)

This output value is only calculated if selected using the Con-

fig.Output.Heat.Select = 1 (default value) parameter. If not selected,

this output is always FALSE.

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8.6 PID_Temp instruction

Parameter and type

Data type

Description

OutputCool_PWM¹

OUT

Bool

Pulse-width-modulated output value for cooling. (Default value: FALSE)

This output value is only calculated if selected using the Con-

fig.Output.Cool.Select = 1 (default value) parameter. If not selected, this

output is always FALSE.

SetpointLimit_H

OUT

Bool

Setpoint high limit. (Default value: FALSE)

If SetpointLimit_H = TRUE, the absolute setpoint upper limit is reached

(Setpoint ≥ Config.SetpointUpperLimit).

The setpoint is limited to Config.SetpointUpperLimit.

SetpointLimit_L

OUT

Bool

Setpoint low limit. (Default value: FALSE)

If SetpointLimit_L = TRUE, the absolute setpoint lower limit is reached

(Setpoint ≤ Config.SetpointLowerLimit).

The setpoint is limited to Config.SetpointLowerLimit.

InputWarning_H

OUT

Bool

If InputWarning_H = TRUE, the process value has reached or exceed-

ed the warning high limit. (Default value: FALSE)

InputWarning_L

OUT

Bool

If InputWarning_L = TRUE, the process value has reached or fallen

below the warning low limit. (Default value: FALSE)

State

OUT

Int

Current operating mode of the PID controller. (Default value: 0)

You can change the operating mode using the Mode input parameter

and a rising edge at ModeActivate:

• State = 0: Inactive

• State = 1: Pre-tuning

• State = 2: Fine tuning

• State = 3: Automatic mode

• State = 4: Manual mode

• State = 5: Substitute output value with error monitoring

Error

OUT

Bool

If Error = TRUE, at least one error message is pending in this cycle.

(Default value: FALSE)

Note: The Error parameter in V1.x PID was the ErrorBits field that con-

tained the error codes. It is now a Boolean flag indicating that an error

has occurred.

ErrorBits

OUT

DWord

The PID_Temp instruction, ErrorBits parameters table

(Page 220)defines the error messages that are pending. (Default value:

DW#16#0000 (no error)). ErrorBits is retentive and is reset upon a

rising edge at Reset or ErrorAck.

Note: In V1.x, the ErrorBits parameter was defined as the Error pa-

rameter and did not exist.

Warning

OUT

DWord

The PID_Temp instruction, Warning parameters table defines the user-

relevant warning messages that are pending. (Default value:

DW#16#0000 (no warning)).

WarningInternal

OUT

DWord

The PID_Temp instruction, WarningInternal parameters table defines

the warning internal messages that are pending (includes all warnings).

(Default value: DW#16#0000 (no warning internal)).

1

You can use the outputs of the Output, Output_PER, and Output_PWM parameters in parallel.

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8.6 PID_Temp instruction

PID_Temp controller operations

The following block diagrams illustrate the PID_Temp instruction standard and cascade

operations:

Figure 8-6

PID_Temp_Operation_Block_Diagram

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8.6 PID_Temp instruction

Figure 8-7

PID_Temp_Cascade_Operation_Block_Diagram

8.6.3

Cascading controllers

You can cascade temperature PID controllers to process more than one temperature that

depend on the same actuator.

Call order

You must call cascaded PID controllers in the same OB cycle. First, you must call the

master, then, the next slave(s) in the control signal flow, and finally on to the last slave in the

cascade. The PID_Temp instruction does not make an automatic check of call order.

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8.6 PID_Temp instruction

Communication connections

When cascading controllers, you must connect the master and slave so that they can share

information with each other. You must connect a slave’s “Master” IN/OUT parameter to its

master’s “Slave” IN/OUT parameter in the signal flow direction.

This shows a connection of PID_Temp controllers in a cascade with two sub-cascades:

"PID_Temp1" provides the setpoint. The configuration connects the outputs of "PID_Temp2",

"PID_Temp3", "PID_Temp5", "PID_Temp6", and "PID_Temp8" to the process:

Figure 8-8

PID_Temp_Cascading_communication_connection

Replacement setpoint

The PID_Temp instruction provides a second setpoint input at the “ReplacementSetpoint”

parameter that you can activate by setting the parameter “ReplacementSetpointOn” = TRUE.

You can use “ReplacementSetpoint” as your setpoint input during commissioning or tuning of

a slave controller without having to disconnect the output-to-setpoint connection between

master and slave. This connection is necessary for normal operation of the cascade.

In this way, you do not have to change your program and download it if you want to

temporarily separate a slave from its master. You only have to activate the

"ReplacementSetpoint" and deactivate it again when you finish.The setpoint value is

effective for the PID algorithm when you can see the value at the “CurrentSetpoint”

parameter.

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8.6 PID_Temp instruction

Anti-windup

A slave in a cascade gets its setpoint from the output of his master. If the slave reaches its

own output limits while the master still sees a control deviation (setpoint - input), the master

freezes or reduces its integration contribution to prevent a so-called "WindUp". In case of a

"WindUp", the master increases its integration contribution to a very large value and must

reduce it first, before the controller can again have a normal reaction. Such a "WindUp"

affects the dynamic of the control negatively. The PID_Temp provides ways to prevent this

effect in a cascade by configuring the parameter “Config.Cascade.AntiWindUpMode” of the

master controller:

Value

Description

0

Deactivates Anti-Windup functionality.

1

Reduces the integration contribution of the master controller at the ratio “slaves

in limitation” to “existing slaves” (parameter “CountSlaves”).

2

Freezes the integration contribution of the master as soon as one slave reaches

its limitation. Only relevant if "Config.Cascade.IsMaster" = TRUE.

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8.7 PID_Temp instruction ErrorBit parameters

8.7

PID_Temp instruction ErrorBit parameters

If the PID controller has several warnings pending, it displays the values of the error codes

by means of binary addition. The display of error code 0003, for example, indicates that the

errors 0001 and 0002 are pending.

Table 8- 11 PID_Temp instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

0000

No error

0001 ^{1, 2}

The Input parameter is outside the process value limits.

Input > Config.InputUpperLimit

Input < Config.InputLowerLimit

0002 ^{2, 3}

Invalid value at the Input_PER parameter. Check whether an error is pend-

ing at the analog input.

0004 ⁴

Error during fine tuning. Oscillation of the process value could not be main-

tained.

0008 ⁴

Error at start of pre-tuning. The process value is too close to the setpoint.

Start fine tuning.

0010 ⁴

The setpoint was changed during tuning.

Note: You can set the permitted fluctuation on the setpoint at the Cancel-

TuningLevel tag.

0020

Pre-tuning is not permitted during fine tuning.

Note: If ActivateRecoverMode = TRUE before the error occurred,

PID_Temp remains in fine tuning mode.

0040 ⁴

Error during pretuning. The cooling could not reduce the process value.

0080 ⁴

Error during pre-tuning. Incorrect configuration of output value limits.

Check whether the limits of the output value are configured correctly and

match the control logic.

0100 ⁴

Error during fine tuning resulted in invalid parameters.

0200 ^{2, 3}

Invalid value at the Input parameter: Value has an invalid number format.

0400 ^{2, 3}

Calculation of the output value failed. Check the PID parameters.

0800 ^{1, 2}

Sampling time error: PID_Temp is not called within the sampling time of the

cyclic interrupt OB.

1000 ^{2, 3}

Invalid value at the Setpoint parameter: Value has an invalid number format.

10000

Invalid value at the ManualValue parameter: Value has an invalid number

format.

Note: If ActivateRecoverMode = TRUE before the error occurred,

PID_Temp uses SubstituteOutput as the output value. As soon as you as-

sign a valid value in the ManualValue parameter, PID_Temp uses it as the

output value.

20000

Invalid value at the SubstituteValue tag: Value has an invalid number for-

mat.

PID_Temp uses the output value low limit as the output value.

Note: If automatic mode was active before the error occurred, Acti-

vateRecoverMode = TRUE, and the error is no longer pending, PID_Temp

switches back to automatic mode.

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8.7 PID_Temp instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

40000

Invalid value at the Disturbance parameter: Value has an invalid number

format.

Note: If automatic mode was active and ActivateRecoverMode = FALSE

before the error occurred, Disturbance is set to zero. PID_Temp remains in

automatic mode.

Note: If pre-tuning or fine tuning mode was active and ActivateRecover-

Mode = TRUE before the error occurred, PID_Temp switches to the operat-

ing mode that is saved in the Mode parameter. If Disturbance in the current

phase has no effect on the output value, tuning is not canceled.

200000

Error with master in the cascade. Slaves are not in automatic mode or have

a substitute setpoint enabled, preventing tuning of the master.

400000

The PID controller does not permit pretuning for heating while cooling is

active.

800000

The process value must be close to the setpoint in order to start pretuning

for cooling.

1000000

Error starting tuning. “Heat.EnableTuning” and “Cool.EnableTuning” are not

set or do not match the configuration.

2000000

Pretuning for cooling requires successful pretuning for heating.

4000000

Error starting fine tuning. “Heat.EnableTuning” and “Cool.EnableTuning”

cannot be set at the same time.

8000000

Error during PID parameter calculation resulted in invalid parameters (for

example, negative Gain; the current PID parameters remain unchanged and

tuning has no effect).

1

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,

PID_Temp remains in automatic mode.

2

Note: If pre-tuning or fine tuning mode was active before the error occurred and ActivateRecover-

Mode = TRUE, PID_Temp switches to the operating mode that is saved in the Mode parameter.

3

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,

PID_Compact outputs the configured substitute output value. As soon as the error is no longer

pending, PID_Temp switches back to automatic mode.

4

Note: If ActivateRecoverMode = TRUE before the error occurred, PID_Temp cancels the tuning

and switches to the operating mode that is saved in the Mode parameter.

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8.8 Configuring the PID_Compact and PID_3Step controllers

8.8

Configuring the PID_Compact and PID_3Step controllers

The parameters of the technology object determine the operation of the PID control-

ler. Use the icon to open the configuration editor.

Table 8- 12 Example configuration settings for the PID_Compact instruction

Settings

Description

Basic

Controller type

Selects the engineering units.

Invert the control logic

Allows selection of a reverse-acting PID loop.

• If not selected, the PID loop is in direct-acting mode and the output of PID loop

increases if input value < setpoint.

• If selected, the output of the PID loop increases if the input value > setpoint.

Enable last mode after

Restarts the PID loop after it is reset or if an input limit has been exceeded and

CPU restart

returned to the valid range.

Input

Selects either the Input parameter or the Input_PER parameter (for analog) for the

process value. Input_PER can come directly from an analog input module.

Output

Selects either the Output parameter or the Output_PER parameter (for analog) for

the output value. Output_PER can go directly to an analog output module.

Process

Scales both the range and the limits for the process value. If the process value goes below the low limit or

value

above the high limit, the PID loop goes to inactive mode and sets the output value to 0.

To use Input_PER, you must scale the analog process value (input value).

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8.8 Configuring the PID_Compact and PID_3Step controllers

Table 8- 13

Example configuration settings for the PID_3Step instruction

Settings

Description

Basic

Controller type

Selects the engineering units.

Invert the control logic

Allows selection of a reverse-acting PID loop.

• If not selected, the PID loop is in direct-acting mode, and the output of PID loop

increases if the input value < setpoint).

• If selected, the output of the PID loop increases if the input value > setpoint.

Activate mode after

Restarts the PID loop after it is reset or if an input limit has been exceeded and

CPU restart

returned to the valid range.

Set Mode to: Defines the mode that the user wants the PID to go to after restart.

Input

Selects either the Input parameter or the Input_PER parameter (for analog) for the

process value. Input_PER can come directly from an analog input module.

Output

Selects either to use the digital outputs (Output_UP and Output_DN) or to use the

analog output (Output_PER) for the output value.

Feedback

Selects the type of device status returned to the PID loop:

• No feedback (default)

• Feedback

• Feedback_PER

Process

Scales both the range and the limits for the process value. If the process value goes below the low limit or

value

above the high limit, the PID loop goes to inactive mode and sets the output value to 0.

To use Input_PER, you must scale the analog process value (input value).

Actuator

Motor transition

Sets the time from open to close for the valve. (Locate this value on the data sheet or

time

the faceplate of the valve.)

Minimum ON time

Sets the minimum movement time for the valve. (Locate this value on the data sheet or

the faceplate of the valve.)

Minimum OFF

Sets the minimum pause time for the valve. (Locate this value on the data sheet or the

time

faceplate of the valve.)

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8.8 Configuring the PID_Compact and PID_3Step controllers

Settings

Description

Reaction to error

Defines the behavior of the valve when an error is detected or when the PID loop is

reset. If you select to use a substitute position, enter the "Safety position". For analog

feedback or analog output, select a value between the upper or lower limit for the out-

put. For digital outputs, you can choose only 0% (off) or 100% (on).

Scale Position

• "High end stop" and "Lower end stop" define the maximum positive position (full-

Feedback¹

open) and the maximum negative position (full-closed). "High end stop" must be

greater than "Lower end stop".

• "High limit process value" and "Low limit process value" define the upper and lower

positions of the valve during tuning and automatic mode.

• "FeedbackPER" ("Low" and "High") defines the analog feedback of the valve posi-

tion. "FeedbackPER High" must be greater than "FeedbackPER Low".

Advanced

Monitoring process

Sets the warning high and low limits for the process value.

value

PID parameters

If the user wishes, he can enter his own PID tuning parameters in this window. The

“Enable Manual Entry” check box must be checked to allow this.

1

"Scale Position Feedback" is editable only if you enabled "Feedback" in the "Basic" settings.

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8.9 Configuring the PID_Temp controller

8.9

Configuring the PID_Temp controller

The parameters of the technology object determine the operation of the PID control-

ler. Use the icon to open the configuration editor.

Table 8- 14 Example configuration settings for the PID_Temp instruction

Settings

Description

Basic

Controller type

Selects the engineering units.

Activate mode

Restarts the PID loop after it is reset or if an input limit has been

after CPU restart

exceeded and returned to the valid range.

Set Mode to: Defines the mode that the user wants the PID to go to

after restart.

Input

Selects either the Input parameter or the Input_PER parameter (for

analog) for the process value. Input_PER can come directly from an

analog input module.

Output Heat

Selects either to use the digital outputs (OutputHeat and Out-

putHeat_PWM) or to use the analog output (OutputHeat_PER (ana-

log)) for the output value.

Output Cool

Selects either to use the digital outputs (OutputCool and Out-

putCool_PWM) or to use the analog output (OutputCool_PER (ana-

log)) for the output value.

Process

Scales both the range and the limits for the process value. If the process value goes be-

value

low the low limit or above the high limit, the PID loop goes to inactive mode and sets the

output value to 0.

To use Input_PER, you must scale the analog process value (input value).

Cascade

Controller is mas-

Sets the controller as a master and selects the number of slaves.

ter

Controller is slave

Sets the controller as a slave and selects the number of masters.

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8.9 Configuring the PID_Temp controller

Controller type

Setting

TO-DB parameter

Data

Value range

Description

type

Physical

"PhysicalQuantity"

Int

• General

Pre-selection for physical

quantity

(Enu

unit value

• Temperature

m)

No multi-value control

(=default)

and not editable in online

mode of functional view.

Unit of

"PhysicalUnit

Int

• General: Units =

User unit selection is set

meas-

(Enu

back to “0” if you change

%

urement

m)

the physical quantity.

• Temperature:

Units (possible

selections) =

-

°C (=default)

–

°F

– K

Activate

"RunModeByStartup"

Bool

Checkbox

If set to TRUE (=default),

mode

the controller switches to

after

the state that is stored in

CPU

the “Mode” variable after

restart

a powercycle (Power on -

off - on) or PLC STOP-to-

RUN transition. Other-

wise, the PID_Temp

remains in “Inactive”

mode.

Set

"Mode"

Int

Modes (possible

The engineering station

mode to

(Enu

selections):

(ES) sets the start value

m)

of the“Mode” variable

•

0: Inactive

according to user selec-

•

1: Pretuning

tion.The default value of

•

2: Fine tuning

Mode (stored inTO-DB) is

Manual Mode.

•

3: Automatic

mode

•

4: Manual mode

(=default)

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8.9 Configuring the PID_Temp controller

Input / output parameters

Setting

TO-DB parameter

Data

Value range

Description

type

Setpoint

Setpoint

Real)

Real

Only accessible in Prop-

erty Page.

No multi value control in

online mode of function-

al view.

Selection

"Config.InputPerOn"

Bool

Bool

Selects which kind of

input

(Enu

input to use.

m)

Possible selections:

• FALSE: “Input” (Re-

al)

• TRUE: “Input_PER

(analog)”

Input

Input or Input_PER

Real

Real or Int

Only accessible in Prop-

or Int

erties page.

No multi value control in

online mode of function-

al view.

Selection

"Config.Output.Heat.Select"

Int

2 >= Config.Output.

Selects which kind of

Output

(Enu

Heat.Select

output to use for heating.

(heating)

m)

>= 0

Possible selections:

•

“OutputHeat” (Real)

•

“OutputHeat_PWM”

(Bool) (=default)

•

“OutputHeat_PER

(analog)” (Word)

Is set to “OutputHeat”

once, if “This controller

is a master” checkbox in

the “Cascade” section is

activated by user.

Output

OutputHeat, OutputHeat_PER,

Real

Real, Int, or Bool

Only accessible in Prop-

(heating)

or OutputHeat_PWM

or Int

erties page.

or

No multi value control in

Bool

online mode of function-

al view.

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8.9 Configuring the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Activate

"Config.ActivateCooling"

Bool

Bool

Checking this checkbox:

output

•

Sets the "Con-

(cooling)

fig.Output.

Heat.PidLowerLimit

= 0.0 once.

•

Sets the

"Con-

fig.ActivateCooling"

parameter to TRUE,

instead of FALSE if

unchecked

(=default).

•

Activates all other

“Output (cooling)”

controls (in “Basic

settings” and other

views).

•

Changes the line

from the PID symbol

to the controls from

gray to black.

•

“This controller is a

master” checkbox in

the “Cascade” sec-

tion is disabled.

Note: Only available if

you do not configure the

controller as a master for

a cascade (“This control-

ler is a master”checkbox

in the “Cascade” section

is deactivated;

"Con-

fig.Cascade.IsMaster" =

FALSE).

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8.9 Configuring the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Selection

"Config.Output.Cool.Select"

Int

2 >= Config.Output.

Selects which kind of

Output

(Enu

Heat.Select

output to use for cooling.

(cooling)

m)

>= 0

Possible selections:

•

“OutputCool” (Real)

•

“OutputCool_PWM”

(Bool) (=default)

•

“OutputCool_PER

(analog)” (Word)

Only available if you

check “Activate output

(cooling)”;

(Config.ActivateCooling

= TRUE).

Output

OutputCool, OutputCool_PER,

Real

Real, Int, or Bool

Only accessible in Prop-

(cooling)

or OutputCool_PWM

or Int

erties page.

or

No multi value control in

Bool

online mode of function-

al view.

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8.9 Configuring the PID_Temp controller

Cascade parameters

The following parameters enable you to select controllers as masters or slaves and to

determine the number of slave copntrollers that receive their setpoint directly from the

master controller:

Setting

TO-DB parameter

Data

Value range

Description

type

This

"Config.Cascade.IsMaster"

Bool

Bool

Shows if this controller is

controller

a master in a cascade.

is a

When you check this

master

checkbox, you perform

the following:

• Set the parameter

"Con-

fig.Cascade.IsMaster

" to TRUE, instead of

FALSE if unchecked

(=default).

• Set “Selection Output

(heating)” in “Input /

output parameters”

section to “Out-

putHeat” once (Con-

fig.Output.Heat.Selec

t = 0).

• Enable “Number of

Slaves” input field.

• Disable “Activate

output (cooling)”

checkbox in “Input /

output parameters”

section.

Note: Only available if

cooling output of this

controller is deactivated

(“Activate output (cool-

ing)” checkbox in “Input /

output parameters” sec-

tion deactivated (Con-

fig.ActivateCooling =

FALSE).

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8.9 Configuring the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Number

"Config.Cascade.CountSlaves"

Int

255 >= Con-

Number of slave control-

of slaves

fig.Cascade.

lers that get their set-

CountSlaves

point directly from this

>= 1

master controller. The

PID_Temp instruction

processes this value,

along with others, for

anti-windup-

handling."Number of

slaves is only available if

“This controller is a mas-

ter” checkbox is activat-

ed (Con-

(Con-

fig.Cascade.IsMaster =

TRUE).

This

"Config.Cascade.IsSlave"

Bool

Bool

Shows if this controller is

controller

a slave in a cascade.

is a

When you check this

slave

checkbox, you set the

parameter "Con-

fig.Cascade.IsSlave" to

TRUE, instead of FALSE

if unchecked (=default).

You must check this

checkbox in the property

page to enable the “Se-

lectionMaster” dropdown

list.

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8.9 Configuring the PID_Temp controller

Example: Cascading controllers

In the “Basic settings” dialog below, you see the “Input / output parameters” section and the

“Cascade” section for slave controller "PID_Temp_2" after selecting "PID_Temp_1" as

master. You make the connections between master and slave controller:

Network 1: In these networks, you make the connection between the "PID_Temp_1" master

and the "PID_Temp_2" slave in the programming editor:

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8.9 Configuring the PID_Temp controller

Network 2: You make the connection between the "PID_Temp_1" master’s “OutputHeat” and

"Slave" parameters to the "PID_Temp_2" slave’s “Setpoint” and "Master" parameters,

respectively:

Autotuning of temperature processes

The PID_Temp instruction provides two modes for auto tuning:

●

“Pretuning” (parameter “Mode” = 1)

●

“Finetuning” (parameter “Mode” = 2)

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8.9 Configuring the PID_Temp controller

Depending on the controller configuration, different variants of these tuning methods are

available:

Configuration

Controller with heating

Controller with heating and

Controller with heating and

output

cooling output using cool-

cooling output using two

ing factor

sets of PID parameters

Associated

• Config.ActivateCooling

• Config.ActivateCooling

• Config.ActivateCooling

TO-DB values

= FALSE

= TRUE

= TRUE

• Con-

• Con-

• Con-

fig.AdvancedCooling

fig.AdvancedCooling =

fig.AdvancedCooling =

= irrelevant

FALSE

TRUE

Available tun-

•

“Pretuning heating”

•

“Pretuning heating”

•

“Pretuning heating and

ing methods

cooling”

•

“Fine tuning heating"

•

“Fine tuning heating"

(cooling offset cannot

(cooling offset can be

• "Pretuning heating”

be used)

used)

•

“Pretuning cooling”

•

“Fine tuning heating”

(cooling offset can be

used)

•

“Fine tuning cooling”

(heating offset can be

used)

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8.9 Configuring the PID_Temp controller

Output value limits and scaling

Cooling activation disabled

If you configure the PID_Temp instruction as master for a cascade “Activate output (cooling)”

checkbox in “Basic settings” view is unchecked and disabled, all settings in the “Output

settings” view that depend on cooling activation are disabled, too.

The figure below shows the "Output value limits and scaling” section in the “Output settings”

view with cooling deactivated (OutputHeat_PWM selected in “Input / output parameters” view

and OutputHeat always enabled):

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8.9 Configuring the PID_Temp controller

Cooling activation enabled

The figure below shows the ”Output value limits and scaling” section in “Output settings”

view with cooling activated (OutputCool_PER and OutputHeat_PWM selected in “Input /

output parameters” view; OutputCool and OutputHeat always enabled):

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8.9 Configuring the PID_Temp controller

Operation modes

To change the mode of operation manually, the user needs to set the “Mode” in-out

parameter of the controller and activate it by setting “ModeActivate” from FALSE to TRUE

(rising edge triggered). You must reset “ModeActivate” before the next mode change; it does

not reset automatically.

Output parameter “State” shows the current operating mode and is set to the requested

“Mode” if possible. The “State” parameter cannot be changed directly; it is only changed

through the “Mode” parameter or automatic operating mode changes by the controller.

"Mode" /

Name

Description

"State"

0

Inactive

The PID_Temp instruction:

• Deactivates the PID-algorithm and pulse width modulation

• Sets to "0" (FALSE) all controller outputs (OutputHeat, OutputCool, Out-

putHeat_PWM,OutputCool_PWM, OutputHeat_PER, OutputCool_PER), regardless of

configured output limits or offsets. You can reach this mode by setting “Mode” = 0,

“Reset” = TRUE, or by error.

1

Pretuning

This mode determines the parameters during first start up of the controller.

(startup tun-

Unlike the PID_Compact, for the PID_Temp, you must select if you require heating tuning,

ing / SUT)

cooling tuning, or both with the “Heat.EnableTuning” and “Cool.EnableTuning” parame-

ters.

You can activate "Pretuning" from Inactive, Automatic mode, or Manual mode.

If tuning is successful, PID_Temp switches to Automatic mode. If tuning is unsuccessful,

the switchover of the operating mode depends on “ActivateRecoverMode”.

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PID is easy

8.9 Configuring the PID_Temp controller

"Mode" /

Name

Description

"State"

2

Fine tuning

This mode determines the optimum parameterization of the PID controller at the setpoint.

(tuning in run

Unlike the PID_Compact, for the PID_Temp, you must select if you require heating tuning

/ TIR)

or cooling tuning with the “Heat.EnableTuning” and “Cool.EnableTuning” parameters.

You can activate "Finetuning" from Inactive, Automatic mode, or Manual mode.

If tuning is successful, PID_Temp switches to Automatic mode. If tuning is not successful,

the switchover of the operating mode depends on “ActivateRecoverMode”.

3

Automatic

In Automatic mode (the standard PID control mode), the result of the PID-algorithm de-

mode

termines the output values.

PID_Temp switches to Inactive if an error occurs and “ActivateRecoverMode” = FALSE. If

an error occurs and “ActivateRecoverMode” = TRUE, the switchover of the operating

mode depends on the error. Refer to PID_Temp instruction ErrorBit parameters

(Page 220) for further information.

4

Manual mode

In this mode, the PID controller scales, limits, and transfers the value of parameter “Man-

ualValue” to the outputs.

The PID controller assigns “ManualValue” in the scaling of the PID-algorithm

(like“PidOutputSum”), so its value decides if it is effective at the heating or cooling out-

puts.

You can reach this mode by setting “Mode” = 4 or “ManualEnable”= TRUE.

5

Substitute

You can activate this mode by setting "Mode" = 5. The mode is an automatic error reac-

output value

tion of the controller if Automatic mode is active at the moment the error occurs:

with error

• SetSubstituteOutput = FALSE (Last valid output value)

monitoring

(Recover

• SetSubstituteOutput = TRUE (Value stored in parameter "SubstituteOutput")

mode)

When PID_Temp is in “Automatic mode” and the “ActivateRecoverMode” parameter =

TRUE, PID_Temp changes to this

mode in the case of the following errors:

•

“Invalid value at "Input_PER" parameter. Check for an error at the analog input (for

example, wire broken)." (ErrorBits = DW#16#0002)

•

“Invalid value at "Input" parameter. Value is not a number.” (ErrorBits = DW#16#0200)

•

“Calculation of output value failed. Check the PID parameters.” (ErrorBits =

DW#16#0400)

•

“Invalid value at "Setpoint" parameter. Value is not a number.” (ErrorBits =

DW#16#1000)

If the error is no longer pending, PID_Temp will switch back to Automatic mode automati-

cally.

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8.10 Commissioning the PID_Compact and PID_3Step controllers

8.10

Commissioning the PID_Compact and PID_3Step controllers

Use the commissioning editor to configure the PID controller for autotuning at startup

and for autotuning during operation. To open the commissioning editor, click the icon

on either the instruction or the project navigator.

Table 8- 15 Sample commissioning screen (PID_3Step)

• Measurement: To display the setpoint, the pro-

cess value (input value) and the output value in a re-

al-time trend, enter the sample time and click the

"Start" button.

• Tuning mode: To tune the PID loop, select either

"Pre-tuning" or "Fine tuning" (manual) and click the

"Start" button. The PID controller runs through multi-

ple phases to calculate system response and update

times. The appropriate tuning parameters are calcu-

lated from these values.

After the completion of the tuning process, you can

store the new parameters by clicking the "Upload PID

parameters" button in the "PID Parameters" section of

the commissioning editor.

If an error occurs during tuning, the output value of the

PID goes to 0. The PID mode then is set to "inactive"

mode. The status indicates the error.

PID start value control

You can edit the actual values of the PID configuration parameters so that the behavior of

the PID controller can be optimized in online mode.

Open the "Technology objects" for your PID controller and its "Configuration" object. To

access the start value control, click the "eyeglasses icon" in the upper left corner of the

dialog:

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PID is easy

8.10 Commissioning the PID_Compact and PID_3Step controllers

You can now change the value of any of your PID controller configuration parameters as

shown in the figure below.

You can compare the actual value to the project (offline) start value and the PLC (online)

start value of each parameter. This is necessary to compare online/offline differences of the

Technology object data block (TO-DB) and to be informed about the values that will be used

as current values on the next Stop-to-Start transition of the PLC. In addition, a compare icon

gives a visual indication to help easily identify online/offline differences:

The figure above shows the PID parameter screen with compare icons showing which

values are different between online and offline projects. A green icon indicates that the

values are the same; a blue/orange icon indicates that the values are different.

Additionally, click the parameter button with the downward arrow to open a small window

that shows the project (offline) start value and the PLC (online) start value of each

parameter:

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8.11 Commissioning the PID_Temp controller

8.11

Commissioning the PID_Temp controller

Use the commissioning editor to configure the PID controller for autotuning at startup

and for autotuning during operation. To open the commissioning editor, click the icon

on either the instruction or the project navigator.

Table 8- 16 Sample commissioning screen (PID_Temp)

Measurement: To display the setpoint, the process value

(input value) and the output value in a real-time trend,

enter the sample time and click the "Start" button.

Tuning mode: To tune the PID_Temp loop, select either

"Pretuning" or "Finetuning" (manual) and click the "Start"

button. The PID controller runs through multiple phases

to calculate system response and update times. The

appropriate tuning parameters are calculated from these

values.

After the completion of the tuning process, you can store

the new parameters by clicking the "Upload PID parame-

ters" button in the "PID Parameters" section of the com-

missioning editor.

If an error occurs during tuning, the output value of the

PID goes to "0". The PID mode then is set to "inactive"

mode. The status indicates the error.

PWM limits

Actuators that are controlled with the software PWM function of the PID_Temp may need to

be protected from too short pulse durations (for example, a thyristor relay needs to be turned

on for more than 20 ms before it can react at all); you assign a minimum on time. The

actuator can also neglect short impulses and therefore corrupt the control quality. A

minimum off time can be necessary (for example, to prevent overheating).

To show up the PWM limits view, you must open the functional view in the Technology

objects (TO) configuration and select “PWM limits” from the “Advanced settings” node in the

navigation tree.

If you open the “PWM limits” view in the functional view and activate monitoring

(“glasses”button), all controls show the online monitor value from TO-DB with orange

background color and multi-value control, and you can edit the values (if configuration

conditions are fulfilled; refer to the table below).

241

PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Minimum

"Config.Output.Heat.

Real

100000.0

A pulse at Out-

on

MinimumOnTime"

>= "Config.Output.

putHeat_PWM" is

Heat.

never shorter than this

time (heat-

MinimumOnTime

value.

ing) ^1,2

>= 0.0

Minimum

"Config.Output.Heat.

Real

100000.0

A break at Out-

off

MinimumOffTime"

>= "Config.Output.

putHeat_PWM is nev-

Heat.

er shorter than this

time (heat-

MinimumOffTime

value.

ing)

1,2

>= 0.0

Minimum

"Config.Output.Cool.

Real

100000.0

A pulse at Out-

on

MinimumOnTime"

>= Config.Output.

putCool_PWM is nev-

Cool.

er shorter than this

time (cool-

1,3,4

MinimumOnTime

value.

ing)

>= 0.0

Minimum

"Config.Output.Cool.

Real

100000.0

A break at Out-

off

MinimumOffTime"

>= Config.Output.

putCool_PWM is nev-

Cool.

er shorter than this

time (cool-

MinimumOffTime

value.

ing) ^1,3,4

>= 0.0

1

The field displays "s" (seconds) as the time units.

2

If the·selection Output (heating) in “Basic settings” view is not “OutputHeat_PWM” (Con-

fig.Output.Heat.Select = TRUE), you should set this value to "0.0".

3

If selection Output (cooling) in “Basic settings” view is not “OutputCool_PWM” (Con-

fig.Output.Cool.Select = TRUE), you should set this value to "0.0".

4

Only available if you check “Activate output (cooling)” in “Basic settings” view (Con-

fig.ActivateCooling = TRUE).

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