isolated RS485 connection

Hello there,

i want to isolate my 485 IC from controller via opto coupler IC, but i have single power supply for the circuit.
Could i make my circuit opto-isotated from that single power supply?, because in any case the GNDs are common.
Is there any alternative way to isolate it by using single PS?
Please reply!!!!

Thanks in advance

To have a complete isolation barrier you must need two supplies. if you do not have any other source then if you have a transformer in your power supply section (or use one) which will give you two different coils for power supply (isolated in nature). so from input there is single source but on board they are two.