hi.
please suggest me the circuit diagram details for desighning a 4 to 20mA simulator from direct 230V ac supply line.

 

Start here.

http://www.bapihvac.com/CatalogPDFs/I_App_Notes/Understanding_Current_Loops.pdf

You will need a power supply and a transmitter. What are you trying to read? Pressure? Temperature? Position?

230volt AC cannot be used directly, It will need to be transformed down to a lower voltage. You CAN use AC for power. Read the pdf. It just can't be 230VAC, more like 24VAC

 

I built a circuit - posted recently by me in this forum - to use a 4-20mA meter I had on hand as a DVM, with which I could then monitor voltage and current in a power supply. The circuit uses a dual op-amp, one amp to provide both an offset to produce 4 mA at zero volts, and the gain. The second amp follows the current in the loop and adjusts to match the signal coming from the first amp.

Is that what you're looking for? I don't understand what you mean by "simulator".