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Multiple schedules for one output


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  • MVP 2023

I can't tell from your screenshot, but I'm guessing you've assigned the same output to all the schedules.  This is a programming no-no, as the state of the output will be determined by it's last instance in the program.  None of the others will count.

Are all 20 schedules active at the same time?  Not that it matters.

Is there any reason you can't create a different bit for each schedule output and OR them all together for your output?  



I've never tried as many as 20 parallel contacts in one net, as Vision won't let you do it.  So I tried with UniStream, and it did compile without errors:


There are 20 contacts there - trust me.  The minimum zoom out on UniLogic is 70% so I was not able to truly capture the crazy of this network.  But it will work.

Joe T.


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Dear Antal,

the PLC will execute exactly each single command...so if you have 2 or more contiguous "simple coil" command the status of the last win.

to avoid this you have to use the SET and RESET coil; in this way if cois is SET a RESET event has to arise to set it to "0".

however my suggest is have only one place where a coil,  coupled with an output, is SET or RESET...following the relative conditions.

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  • MVP 2023

Antal, it is worth remembering/learning from this one that the same principle applies throughout PLC programming. 

If you have multiple references to any sort of output, the last one in the ladder is the one that is applied.  So if you need to have multiple references, you have to have all those references independently applied to the output in one rung as parallel like Joe says.  Sometimes on complex output involvement, this can even mean the need to "cascade" the individual references.  I do this to break it up into more easily referenced visually  for the human.  In programming, I always try to make it easy to follow the logic to facilitate troubleshooting, which sometimes means more elements seemingly arranged clumsily.  But they are there for a purpose!

All Programmers have their own preferences, but many keep all physical outputs ladder work until the very end of the program.

cheers, Aus

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