View Full Version : Problem FB41 PID

rikita

April 12th, 2015, 04:19 PM

hi , I'm trying to implement PID in step 7 using FB41.the FB41 is implemented in OB35. I know how to set parameters of PID also I know the inputs type, outputs type . the problem I get always max value at the output of the FB41 I dn't know why !

knowing that I set Kp=2 , Ti= 2s , Td= 500ms

taking SP = 2 and PV=1 I get at the output max value (LMN_PER=27648) where is the problem :(

JRW

April 12th, 2015, 04:57 PM

Show a screenshot of your call

rikita

April 12th, 2015, 05:00 PM

the FB41 is in OB35 , thnx for ur help

36325

36326

JRW

April 12th, 2015, 05:11 PM

Are you using PV real or PV Per?

Are you sure this is set correctly ?

PV PER ON

rikita

April 12th, 2015, 05:20 PM

Are you using PV real or PV Per?

Are you sure this is set correctly ?

PV PER ON

yes using PV_IN or PV_PER I get always the max value 36327

JRW

April 12th, 2015, 05:26 PM

With PV per off and a 50.0 SP

And a 45.0 to 55.0 PV - does your LMN still stay at 27648?

rikita

April 12th, 2015, 05:30 PM

at 45° I get 27648

at 55 I get 0

with SP = 50

JRW

April 12th, 2015, 05:34 PM

Ob35 at 100ms?

rikita

April 12th, 2015, 05:36 PM

yes it is at 100 ms :( I can't see where is the problm

JRW

April 12th, 2015, 05:45 PM

Im putting together some screen shots

Wait a minute

rikita

April 12th, 2015, 05:46 PM

ok thank you very much for your help

JRW

April 12th, 2015, 05:52 PM

Heres a simple set up with the PID at defaults except for the inputs as shown

rikita

April 12th, 2015, 05:55 PM

ok I'll try it now thanx a lot for your help :) can u reupload in good quality lol I can't see all parametres sorry

JRW

April 12th, 2015, 05:58 PM

another

rikita

April 12th, 2015, 06:01 PM

how do you use PID control (the other window)?

JRW

April 12th, 2015, 06:40 PM

Go here

Then open your project> open the instance DB for your PID in the ONLINE button

JRW

April 12th, 2015, 06:45 PM

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