How can I modify DMX signal to pass through one decoder to another (daisy chained DMX decoders) one when power is and is not applied?

I've shorted Pin 2 and Pin 3 from the input to the out put . The signal passes through when there is no power on the first DMX Decoder (the one with the signal) in the chain. But when the first DMX Decoder has power the signal dies. Is there a modification I can do to fix this?