Hi to everyone, I have done an intense search on the web and this form, also went on to the download section here to try out a simple RS232 program, so far I can't get it work. Long story short, I am working on a PLC CP1E( w/ built in RS232) to communicate with the PC hyper-terminal . PC will send a string of messages to the PLC, then the PLC will convert the message to a pulse parameter, eg. computer will send ( 90, 40) to PLC, then the PLC will take the string 90 to pulses parameter( PLS2) and 40 will be the duration period. I am willing to learn and try out your sample program, let me know! THank you in advance.