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For general optocouplers like 4N35, 4N25, PC817, etc where the optocoupler is designed to be driven by DC, you need to rectify the 230VAC to ensure that the optocoupler gets a DC voltage. You also need to limit the current to the optocoupler using a series resistor. Calculate the series resistance as R = (Vin - Vf)/If
Remember that if you do not rectify the input using a full-wave rectifier, the opto-coupler will be off for half the cycle.
There are optocouplers that can be fed with AC input (current must obviously be limited). One such common optocoupler is TLP620.
i am going to develope my own protocol for sending 24 bit at a time yesterday i tried for its starting that through usin simulation in proteus and programmed in pic therse a lot of timming problem happening
an iam going to develope it on single wire communication