I am using VB programme to communicate to PLC. I am able to communicate using hyper terminal for 'n' no. of cycles (sending and receiving) but thru the VB application using MS COMM, the communication is perfect only for the first cycle. After completion of first cycle, I am receiving completion signals from PLC and the application sends signals for the second cycle. There is no response from the PLC from next cycle onwards. Can anyone help pleas...