ControlLogix Digital Output to CompactLogix Input

I am looking for information that will provided me with information on how to wire a ControlLogix Digital Output to the CompactLogix Input to turn on a light from the CompactLogix output. Any help would be appreciated. Thanks ahead of time.

You need to know more than you listed. Which model of DO module? Connected to what flavor of DI? The no brainer method would be to use an interposing relay. Depending on voltages, you may need one anyway.

elwittee said:

I am looking for information that will provided me with information on how to wire a ControlLogix Digital Output to the CompactLogix Input to turn on a light from the CompactLogix output. Any help would be appreciated. Thanks ahead of time.

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Check that the voltages match

If the minimum turn-on current for the 120VAC output is less than the minimum turn-on current for the input, that will not require any extra components.

If the minimum turn-on current for the input is lower than the leakage current on the output, you will need a resistor to drop the voltage below the minimum input voltage of the input when the output is off. Then figure out the current to determine what wattage the resistor needs to be.

For example, I have used 2W resistors at 1K in the past for this purpose. I don't remember the specs on the output and the input cards. JHeck, I can't even remember the models of the cards. But they were PLC2 outputs and PLC5 inputs.

ControlLogix 1756-OB16 DC Output module to CompactLogix 1769-L18ER "Input" and turn on "Output" to light. Does that help? I was wanting to use "Produced/Consumed" tags but the CompactLogix is not the correct model to accept "Consumed" tag.

All CompactLogix controllers that have network ports support produced/consumed tags. Take another look at your configurations; a lot of folks don't know how to select a Producer controller that's a lot newer than the Consumer, but it's pretty straightforward.

In general I think you can wire an ordinary 1756-OB16 to an ordinary DC input directly, as long as they share the same DC common. It's the Diagnostic modules that tend to have more "leakage" than the Input modules can ignore.

Even if you can't get the CompactLogix to work with P/C (although I'd take Ken's advice and look at it again) you could write a simple message instruction to move the data. Having said that, if the two controllers are close enough to be hardwired together, why not use the output of the ControlLogix to drive the light?
This isn't homework is it?

Does the ControlLogix have Ethernet ? if they are both on the same network you could just do a MSG between them?

As others have said, either a produced/consumed tag or a MSG instruction would be an extremely simple and straightforward way to move a bit from a ControlLogix to a CompactLogix.