Siemens SIMATIC S7-1200 Function Manual page 79

PWM limits V2
The value at the output parameter Output is transformed into a pulse sequence that is output
at output parameter Output_PWM by means of a pulse width modulation. Output is
calculated in the PID algorithm sampling time, Output_PWM is output in the PID_Compact
sampling time.
The PID algorithm sampling time is determined during pretuning or fine tuning. If manually
setting the PID parameters, you will also need to configure the PID algorithm sampling time.
The PID_Compact sampling time is equivalent to the cycle time of the calling OB.
The pulse duration is proportional to the value at Output and is always an integer multiple of
the PID_Compact sampling time.
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②
③
④
The "Minimum ON time" and the "Minimum OFF time" are rounded to an integer multiple of
the PID_Compact sampling time.
A pulse or a break is never shorter than the minimum ON or OFF time. The inaccuracies this
causes are added up and compensated in the next cycle.
PID control
Function Manual, 03/2017, A5E35300227-AC
PID_Compact sampling time
PID algorithm sampling time
Pulse duration
Break time
Using PID_Compact
4.2 PID_Compact V2
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