My PC tool is VB. I want to receive a data string from FX2n-4AD mitsubishi PLC. I tried MSComm in VB with 9600,n,8,1 settings. Following is the code in form load MSComm1.CommPort = 1 MSComm1.settings = "9600,N,8,1" MSComm1.InputLen = 0 MSComm1.PortOpen = TRUE Text1.Text = MSComm1.Input MSComm1.PortOpen = FALSE Data was easily transfered in DOS mode using PROComm communication software. Mode of communication is RS 232. Can anybody suggest the right way of serial communication using VB for RS 232. MSDN documentation examples were tried. I will be happy if the process of communication at low level is also explained.