Siemens SIMATIC S7-1200 Function Manual page 118

Using PID_3Step
5.2 PID_3Step V2
Setpoint V2
Procedure
Proceed as follows to define a fixed setpoint:
1. Select "Instance DB".
2. Enter a setpoint, e.g. 80° C.
3. Delete any entry in the instruction.
Proceed as follows to define a variable setpoint:
1. Select "Instruction".
2. Enter the name of the REAL variable in which the setpoint is saved.
Program-controlled assignment of various values to the REAL variable is possible, for
example for the time controlled change of the setpoint.
Process value V2
PID_3Step will scale the value of the analog input to the physical quantity if you use the
analog input value directly.
You will need to write a program for processing if you wish first to process the analog input
value. The process value is, for example, not directly proportional to the value at the analog
input. The processed process value must be in floating point format.
Procedure
Proceed as follows to use the analog input value without processing:
1. Select the entry "Input_PER" in the drop-down list "Input".
2. Select "Instruction" as source.
3. Enter the address of the analog input.
Proceed as follows to use the processed process value in floating point format:
1. Select the entry "Input" in the drop-down list "Input".
2. Select "Instruction" as source.
3. Enter the name of the variable in which the processed process value is saved.
Position feedback V2
Position feedback configuration depends upon the actuator used.
● Actuator without position feedback
● Actuator with digital endstop signals
● Actuator with analog position feedback
● Actuator with analog position feedback and endstop signals
118
Function Manual, 03/2017, A5E35300227-AC
PID control