Inverting IO Bool Signals with Automation Builder and AC500


Is there an option in Automation Builder to invert a boolean signal that is connected to an IO module? In Control Builder when using the D810 input card there is a property for each IO variable to invert the signal. This property can be very useful when programming failsafe signals. I am looking for the same option in Automation Builder when using a DI524.

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asked 1 year ago




I can't find a way to Invert a Hardware input with the DI524

My suggestion is to make your first Rung that Input as a NC Contact straight to a Global Bool, then use that same Bool in the rest of your logic.


answered 1 year ago


By MHO on 8/24/2016 | Like (0) | Report

Hello nosttamluap, can you explain 'first Rung'? Do you mean an init step or something else?

By nosttamluap on 8/24/2016 | Like (0) | Report

If you use LD in CodeSys it is the first command line in the Ladder.

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Thats the best solution and most commonly used thing.

That simply read the Field IO as "Normally Open" , later in your Codesys program just press CTRL+N or right Click " NEGATE".

It will invert your desired signal.

But recommended for signals like "EMERGENCY" to make it "NORMALLY CLOSED" on hardware basis.


answered 1 year ago


By MHO on 8/24/2016 | Like (0) | Report

Thank you for that, I totally agree with you that these signals must be inverted on hardware basis. For example our limit switches are NC, but I want to use logical names in my PLC application for this signal. That is why I am looking for a solution to invert the signal again in the PLC.

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