Siemens SIMATIC S7-1200 Function Manual page 120

Using PID_3Step
5.2 PID_3Step V2
Output value V2
PID_3Step offers an analog output value (Output_PER) and digital output values
(Output_UP, Output_DN). Your actuator will determine which output value you use.
● Output_PER
The actuator has a relevant motor transition time and is triggered via an analog output
and controlled with a continuous signal, e.g. 0...10 V or 4...20 mA. The value at
Output_PER corresponds to the target position of the valve, e.g. Output_PER = 13824,
when the valve is to be opened by 50%.
For auto-tuning and anti windup behavior, for example, PID_3Step takes into
consideration that the analog output value has a delayed effect on the process due to the
motor transition time. If no relevant motor transition time is in effect in your process (e.g.
with solenoid valves), so that the output value has a direct and full effect on the process,
use PID_Compact instead.
● Output_UP, Output_DN
The actuator has a relevant motor transition time and is controlled by two digital outputs.
Output_UP moves the valve in the open state direction.
Output_DN moves the valve in the closed state direction.
The motor transition time is taken into consideration in the calculation of the analog output
value as well as in the calculation of the digital output values. It is mainly required for correct
operation during auto-tuning and the anti-windup behavior. You should therefore configure
the motor transition time under "Actuator settings" with the value that the motor requires to
move the actuator from the closed to the opened state.
Procedure
Proceed as follows to use the analog output value:
1. Select the entry "Output (analog)" in the drop-down list "Output".
2. Select "Instruction".
3. Enter the address of the analog output.
Proceed as follows to use the digital output value:
1. Select the entry "Output (digital)" in the drop-down list "Output".
2. Select "Instruction" for Output_UP and Output_DN.
3. Enter the addresses of the digital outputs.
Proceed as follows to process the output value using the user program:
1. Select the entry corresponding to the actuator in the drop-down list "Output".
2. Select "Instruction".
3. Enter the name of the tag you are using to process the output value.
4. Transfer the processed output value to the actuator by means of an analog or digital CPU
output.
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Function Manual, 03/2017, A5E35300227-AC
PID control