Call Without Pulse Generator (Continuous Controller); Call With Pulse Generator (Pulse Controller) - Siemens SIMATIC Manual

2.4.2

Call without Pulse Generator (continuous controller)

Controller Sampling Time CYCLE
You specify the sampling time at the CYCLE parameter. You can also enter the
sampling time using the parameter assignment tool. The sampling time CYCLE
must match the time difference between two calls (cycle time of the cyclic OB
including scan rates).
During controller tuning, the block measures the time between the calls and
compares it with the configured value CYCLE. If there is a difference of >5%, the
optimization will be aborted and STATUS_H = 30005 is set.
Rule of Thumb for the CYCLE Controller Sampling Time
The controller sampling time should not exceed 10 % of the calculated integral time
constant of the controller (TI):
CYCLE ≤ TI/10
2.4.3

Call with Pulse Generator (pulse controller)

Controller Sampling Time CYCLE and Sampling Time of the Pulse Generator
CYCLE_P
If you have activated the pulse generator stage (PULSE_ON = TRUE), you must
enter two sampling times.
•
Enter the sampling time of the pulse generator at the CYCLE_P input. This
must match the clock rate of the calling cyclic interrupt OB. The duration of the
generated pulse is always a whole multiple of this value.
•
At the CYCLE input, you specify the sampling time for the other control
functions of FB 58 "TCONT_CP".
During controller tuning, the block measures the times between the calls and
compares it with the configured value CYCLE. If there is a difference of >5%, the
optimization will be aborted and STATUS_H = 30005 is set.
FB 58 "TCONT_CP" calculates the scan rate and processes the control functions
at the CYCLE sampling rate. Make sure that CYCLE is a whole multiple of
CYCLE_P.
You can select a value for CYCLE that is lower than the pulse repetition period
PER_TM. This can be useful when you require as high a pulse repetition period as
possible to reduce wear on the actuators but when the sampling time needs to be
low due to a fast process.
PID Temperature Control
A5E00125039-02
Continuous Temperature Controller FB 58 "TCONT_CP"
2-15