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valerianlin

OMRON Input Pulse to SET Instruction

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Hi all,

I am fairly new to PLC programming, and just have a simple program regarding an unlatching input. In the picture below, I have STARTCOIL going to the set instruction for a single acting cylinder, LOCATOR_F. My problem is that once the STARTCOIL is actuated, it stays on, and I cannnot use the RSET instruction on LOCATOR_F.

How would I modify the program to make the STARTCOIL pulse once to set the  SET bit, but after that, there is no powerflow through STARTCOIL. In short, I'd like to stimulate a non-latching push button.

I would appreciate any help.

Thank You

Capture.JPG

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I can't quite tell exactly what you're after but.....

If you only want the LOCATOR_F bit to be on for the same amount of time as your input, then change the SET instruction to an output coil. 

If you want the LOCATOR_F bit to be on for a single scan of the program use the UP instruction before the coil you would have put in as above.

If you want it to be on for a certain amount of time (ie 2 seconds) then you should use a timer. I can't recall which pne exactly but the HELP manual should describe each one.

 

If you want I can post a picture showing what any of the above could look like.

 

Are you doing this inside a Function Block, or in a normal ladder section of the main program?

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Right-Click on the STARTCOIL contact and choose Differentiate Up. It will make STARTCOIL to energize the SET instruction only when it transitions from Off to On, so one-shot only.

If you want to re-energize the SET instruction, the said STARTCOIL then should be switched Off first then On again.

 

A keyboard shortcut for the Differentiation is Shift+@ for Differentiate Up, and Shift+% for Differentiate Down.

 

Alternatively you can also use Differentiation on the SET instruction itself. Instead of only SET, change it to @SET. It will then be triggered only when the left-side inputs turning from Off to On.

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