Final Controlling Element Settings V2 - Siemens SIMATIC S7-1200 Function Manual

Using PID_3Step
5.2 PID_3Step V2
5.2.1.3

Final controlling element settings V2

Final controlling element V2
Actuator-specific times
Configure the motor transition time and the minimum ON and OFF times to prevent damage
to the actuator. You can find the specifications in the actuator data sheet.
The motor transition time is the time in seconds the motor requires to move the actuator from
the closed to the opened state. You can measure the motor transition time during
commissioning.
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.
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.
The motor transition time is retentive. If you enter the motor transition time manually, you
must completely download PID_3Step.
Downloading technology objects to device (Page 44)
If you are using "Output_UP" or "Output_DN", you can reduce the switching frequency with
the minimum on and minimum OFF time.
The on or off times calculated are totaled in automatic mode and only become effective
when the sum is greater than or equal to the minimum on or OFF time.
Manual_UP = TRUE or Manual_DN = TRUE in manual mode operates the actuator for at
least the minimum ON or OFF time.
If you have selected the analog output value Output_PER, the minimum ON time and the
minimum OFF time are not evaluated and cannot be changed.
Reaction to error
PID_3Step is preset so that the controller stays active in most cases in the event of an error.
If errors occur frequently in controller mode, this default reaction has a negative effect on the
control response. In this case, check the Errorbits parameter and eliminate the cause of the
error.
NOTICE
Your system may be damaged.
If you output "Current value while error pending" or "Substitute output value while error
pending" in the event of an error, PID_3Step remains in automatic mode even if the
process value limits are violated. This may damage your system.
It is essential to configure how your controlled system reacts in the event of an error to
protect your system from damage.
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Function Manual, 03/2017, A5E35300227-AC
PID control