hi realpars lovers
am working withe the FB41 pid block in (ob35) and here is the parameters am using
COM_RST=MAN_on=PVPER_on=(P ,I,D)SEL=BOOL
CYCLE=2MS / SP_INT is changeble PV_PER=PIW256 LMN_PER=pqw256 and i give values to the gain,Ti Td
the problem i have is that the LMN_per is either 0 or 27648 even if i make changes in PIW256
can any one help (sur there is) :)

LMN_PER = Manipulated Value Peripheral.

LMN_PER is calculated by the formula: LMN_PER= LMN* 27648/100 and is written to the PQW table in the memory location pointed to by the output tag.

The value of LMN_PER (PQW value) is not affected by any changes to the scaling of the input (PIW).

If your output is either 0% or 100% (27648), it is likely your gain or Ti parameter is too high, especially if it is oscillating between the two values. Set your SP to within 1% of the PV, set your gain, Ti and Td to zero, and set your PID to automatic mode. Slowly raise your gain (0.2 or so) and see what output you get.