pid factors and offsets in siemens - PLCS.net

ravilal · September 12th, 2006, 12:20 PM

Can you tell me when and where do we use
PV_FAC and PV_OFF used in PV NORM block in PID loop in FB41 of siemsns S7? and similarly LMN_FAC and
LMN_OFF in LMN NORM block.What are practical applications of using
these factors and offsets in these blocks.what are their uses?what are they for?

dchartier · September 12th, 2006, 11:01 PM

Hello ravilal;

It is a scaling function for the PV input; I've had to use it once to work with a PV that only ranged up to 40%; using the factor and offset for the PV I brought the signal to 0-100% (almost). But noise was also increased. If I had to do it again, I would work on the input transducers instead.
Hope this helps,
Daniel Chartier

parky · September 13th, 2006, 02:04 PM

Another good one is if you make pb negative it acts as reverse controller

September 12th, 2006, 12:20 PM	#1
ravilal Member Join Date: Feb 2006 Location: karachi Posts: 6	pid factors and offsets in siemens Can you tell me when and where do we use PV_FAC and PV_OFF used in PV NORM block in PID loop in FB41 of siemsns S7? and similarly LMN_FAC and LMN_OFF in LMN NORM block.What are practical applications of using these factors and offsets in these blocks.what are their uses?what are they for?

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September 12th, 2006, 11:01 PM	#2
dchartier Member Join Date: May 2003 Posts: 1,492	Hello ravilal; It is a scaling function for the PV input; I've had to use it once to work with a PV that only ranged up to 40%; using the factor and offset for the PV I brought the signal to 0-100% (almost). But noise was also increased. If I had to do it again, I would work on the input transducers instead. Hope this helps, Daniel Chartier

September 13th, 2006, 02:04 PM	#3
parky Member Join Date: Oct 2004 Location: Midlands Posts: 926	Another good one is if you make pb negative it acts as reverse controller

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