What output does your encoder have? My description below is for a simple push/pull or TTL level output, RS422 would need something a bit different though could probably drive four inputs anyway.
It depends on why you think you need to split the signal. Is it because the encoder doesn't give out enough current to drive four inputs or is it because the devices you are sending a signal to are on different power supplies and so you want to have isolation between the signals. Either way the simple answer is to use an opto-coupler/s. If your problem was just power output then one/two will probably be OK as those will give 50mA per channel, if isolation was the issue then you will need four/eight.
Typical isolator RS Components, 533-0019 24Vdc in 0-30Vdc out, see rswww.com, if the issue is just power you can do the same using a transistor and a couple of resistors but I find using a ready made DIN rail mounting package easier.
The push/pull or TTL output on an encoder is nothing special, just think of it a posh proximity sensor that give out lots of pulses.
Bryan
