I am using 5v 4 channel opto coupler relay to turn on/off lights.The relay is in switch board and the micro controller is somewhere at the other end of the room(7 m distance approx for wires).
I am not sure if any voltage drop would be there.can some one please explain if it will really works without issue for 7 m.
thanks in advance
Yes it will work fine, just like any other LED on the end of 7m of wire - an optocoupled relay module
just looks like an (infra-red) LED load, because it is. The current limiting resistor will be much larger
in resistance than the wires so their resistance won't be critical.
All of this supposes each end of the link has its own local supply.