Digital Inputs
At times it may be necessary to use a relay when wiring digital inputs. For example, an existing switch that you want to monitor may allow +24V to pass through it. Because the IG21's digital inputs activate when pulled low to 0V, you need a relay.

Wire the relay following the model above. Terminal labels and voltage of the relay may differ by manufacturer and use case, so make sure to study the circuit diagram accordingly.
Digital Outputs
Digital outputs require a relay when the load requires more voltage or current than the IG21 can provide.

Wire the relay following the model above. Terminal labels on the relay may differ by manufacturer so make sure to study the circuit diagram accordingly.
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