I would like to interface an Entrelec opto coupler to an Allen Bradley SLC 1746-IB16 input module. The module is a sourcing type..ie..must pull up to +24V to turn on input. The output of the opto coupler is an NPN transistor. I as thinking of connecting the emitter pin to the PLC input and tie the collector pin to +24V. When the opto turns on, the transistor should conduct and source 24V to the input. I think this would work. Does anyone see a problem doing this? An NPN transistor would normally be used for sinking an input to common.