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Anhe
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Join Date: Dec 2010
Posts: 2

PLC SR-Function Question

01/29/2011 10:14 AM

Hi

Imagine i creat two SR blocks.

SR block 1: S=I0.0 and R=I0.1 and Q=Q0.0

Now for the question. Can i place a &-function to the S of the SR block number 2, and set the inputs of the &-function to I0.1 and Q0.0.

Will i be able to set the SR block number two this way? Or will I0.1 and Q0.0 never be aktiv at the same time, or not for a time long egnoufh to set the SR block number 2.

Thanks
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JohnDG
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#1

Re: PLC SR-function question

01/29/2011 10:22 AM

This is a "race condition" - the outcome will depend on exactly how your particular PLC operates. I suggest you try a simulation with e.g. Picosoft, Logo!soft or Millenium 3 software.

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Anhe
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Join Date: Dec 2010
Posts: 2
#2

Re: PLC SR-function question

01/29/2011 10:29 AM

Thanks alot. I guess its a solution to be avoided then. Thanks for simulation software tips.
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Bolton_Alan
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#3
In reply to #2

Re: PLC SR-function question

02/04/2011 5:12 AM

Don't know which plc you're using but if you use Q0.0 to energise an off delay timer that that lasts slightly longer than your longest PLC scan time then the timer will still be true for any length of time you want after I0.1 goes true. Example using Siemens

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