Siemens Simatic S7-1500 - Page 483

Instructions
9.4 PID basic functions
PID control
Function Manual, 03/2017, A5E35300227-AC
483
Accuracy of pulse generation
The smaller the pulse generator CYCLE_P is compared to the period duration PER_TM, the
more precise the pulse width modulation is. To achieve sufficiently accurate control, the
following relationship should apply:
CYCLE_P ≤ PER_TM/50
The manipulated value is transformed with a resolution of ≤ 2 % into an impulse.
Note
When calling the controller in the pulse shaper cycle, you must note the following:
Calling the controller in the pulse shaper cycle will cause the process value to be ave
raged.
As a result, at output PV, different values may be at input PV_IN and PV_PER. If you want to
track the setpoint value, you must save the process value at input parameter PV_IN at the
call times for complete controller processing (QC_ACT
= TRUE). For pulse shaper calls
occurring between these times, you must supply the input parameters PV_IN and SP_INT
with the saved process value.
See also
Description TCONT_CP (Page 471)
Mode of operation TCONT_CP (Page 472)
Block diagram TCONT_CP (Page 484)
Input parameters TCONT_CP (Page 486)
Output parameters TCONT_CP (Page 487)
In/out parameters TCONT_CP (Page 488)
Static variables TCONT_CP (Page 489)
Parameter STATUS_H (Page 494)
Parameters STATUS_D (Page 495)