Pulsegen; Description Pulsegen - Siemens SIMATIC S7-1200 Function Manual

Instructions
9.4 PID basic functions
9.4.3

PULSEGEN

9.4.3.1

Description PULSEGEN

The instruction PULSEGEN serves as the structure of a PID controller with impulse output
for proportional actuators. PULSEGEN transforms the input value INV (= LMN of the PID
controller) through modulation of the impulse width in an impulse sequence with a constant
period duration, which corresponds with the cycle time with which the input value is updated.
Application
You can use the PULSEGEN instruction to configure two- or three-step PID controllers with
pulse width modulation. The function is normally used in conjunction with the continuous
controller CONT_C.
Call
The PULSEGEN instruction has an initialization routine that is run through when input
parameter COM_RST = TRUE is set. All the signal outputs are set to zero. COM_RST =
FALSE has to be set after the initialization routine has been completed.
The calculation of the values in the control blocks is only correct if the block is called at
regular intervals. You should therefore call the control blocks in a cyclic interrupt OB (OB 30
to OB 38). Enter the sampling time in the CYCLE parameter.
Responses in the event of an error
The error message word RET_VAL is not evaluated by the block.
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Function Manual, 03/2017, A5E35300227-AC
PID control