Pid Control - Siemens SIMATIC S7-1500 System Manual

4.3.7

PID control

PID controllers are built into all R/H‑CPUs as standard. PID controllers measure the actual value
of a physical variable, for example, temperature or pressure, and compare the actual value
with the setpoint. Based on the resulting error signal, the controller calculates a manipulated
variable that causes the process value to reach the setpoint as quickly and stably as possible.
You can choose from three different PID technology objects:
PID technology object
PID_Compact
PID_3Step
PID_Temp
NOTE
Restriction
The display of the start value in the CPU and the corresponding comparison result in the
configuration editor of the PID technology object is only possible in the RUN-Solo system
state.
Example closed loop control of a valve in a mixer tap
The automation task is to control the valve of a mixer tap according to a desired temperature
setting. You configure the opening and closing of the valve in the PID_3Step technology
object. For this you need:
• An analog input channel for the actual value
• A digital output for "Control upwards" (e.g. open valve)
• A digital output for "Control downwards" (e.g. close valve)
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Description
The PID_Compact technology object provides a PID controller with integrated tuning for propor­
tional-action final controlling elements. Different operating modes are possible with
PID_Compact, e.g:
• Pretuning
• Fine tuning
• Automatic mode
• Manual mode
The PID_3Step technology object provides a PID controller with tuning for valves or actuators
with integrating behavior. You can configure the following controllers:
• Three-point stepping controller with position feedback
• Three-point stepping controller without position feedback
• Valve controller with analog output value
The PID_Temp technology object provides a continuous PID controller with integrated tuning.
PID_Temp is specially designed for temperature control and is suitable for heating or heat­
ing/cooling applications. Two outputs are available, one for heating and one for cooling. You can
also use PID_Temp for other control tasks. PID_Temp can be cascaded. You can use PID_Temp in
manual or automatic mode.
System overview
4.3 S7-1500 R/H-CPUs
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