MRPLC82

Activating PLC Output at the specific time - please help

9 posts in this topic

Evening,

I struggle with simple task...

I need to activate PLC Output at the specific time of a day.

I`m using GSV to obtain PLC time, data is being moved to DIN[7] registers.

Then I have three EQU (Hour / Minute / Second) and at the end of rung there is OTL for output.

Rung below I have two EQU (Hour / Minute) to disable output at different time - OTU.

However every time OTL is energised , OTU on rung below is fired too.

What am I doing wrong here ?

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How long are you wanting to energize for? For that single full minute? If so, why are you using the OTL? The OTE would make it true for that minute only.

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I want to energize it for few hours hence I decided to use OTL. In simple terms when there is 12:00:00 , OTL my output. Output should stay latched until on rung below PLC detects request to unlatch it at 16:00. I hope I explained it well.

Edited by MRPLC82

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Can you do >= and <= and just use the OTE as time suggested?

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I could use OTE, that`s an option, I just though OTL would be more robust solution in case of PLC restart etc.

I have got two conditions on rung 1 , when hour is greater than 11 and less 16 to OTE an output. This should work too.

Going back to my OTL option, what was I doing wrong there, OTL and OTU were active at the same time - condition on rung were not permitting it .

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You need to post your code so we can look at it.

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The OTL and OTU instructions will be highlighted with the current status of the bit. So, once it's OTL'd on, the OTU instruction will be highlighted, even if it's not enabled. To test this, add an XIC at the beginning of the ladder rung and toggle it OFF. That way, you know for sure the OTU isn't active.

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Joe is onto something....:-D

 

the "green" highlight identified value, not that instruction is processed. same would happen if you have contacts (XIC/XIO) in a rung. they get highlighted based on present value of associated variable, even if condition to the left of it is false. color does not indicate "scanned".

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Have you tried just using a limit instruction?

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