Please help me
Hello
For data communication, RS-232 is a 3-wire interface and it is Full-duplex (transmit and recieve at the same time).
But RS-485 (or RS-422) is 2-wire only. Moreover, RS-485 supports the communication between more than 2 boards (2 or more) on the same data bus. However, RS-485 is half-duplex (transmission and reception are not allowed at the same time).
Both RS232 and RS485 support baud rates (speeds) up to 115,200 Kbit/Second.
All you need to do is to buy the convenient drive MAX232 or MAX485 from Maxim. There is a big number of compatible drivers on the market from other manufacturers.
I guess you should also consider some standard protocols when writing your software drivers such as Modbus, Fielbus , ...
Regards
Ahmed Salah