Using Pid_3Step; Technology Object Pid_3Step - Siemens SIMATIC S7-1200 Function Manual

Using PID_3Step

5.1

Technology object PID_3Step

The technology object PID_3Step provides a PID controller with tuning for valves or
actuators with integral response.
You can configure the following controllers:
● Three-point step controller with position feedback
● Three-point step controller without position feedback
● Valve controller with analog output value
PID_3Step continuously acquires the measured process value within a control loop and
compares it with the setpoint. From the resulting control deviation, PID_3Step calculates an
output value through which the process value reaches the setpoint as quickly and steadily as
possible. The output value for the PID controller consists of three actions:
● Proportional action
The proportional action of the output value increases in proportion to the control
deviation.
● I action
The integral action of the output value increases until the control deviation has been
balanced.
● D action
The derivative action increases with the rate of change of control deviation. The process
value is corrected to the setpoint as quickly as possible. The derivative action will be
reduced again if the rate of change of control deviation drops.
The instruction PID_3Step calculates the proportional, integral and derivative parameters for
your controlled system during pretuning. Fine tuning can be used to tune the parameters
further. You do not need to manually determine the parameters.
Additional information
● Overview of software controller (Page 38)
● Add technology objects (Page 40)
● Configure technology objects (Page 42)
● Configuring PID_3Step V2 (Page 116)
● Configuring PID_3Step V1 (Page 138)
Principle
For more information, see the following FAQs in the Siemens Industry Online Support:
● Entry ID 68011827 (https://support.industry.siemens.com/cs/ww/en/view/68011827)
PID control
Function Manual, 03/2017, A5E35300227-AC
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