As Mohmood implied, I've also found that serial communications in 32-bit version of VisualBasic are less than stellar. I used to have no problems with serial comm in 16-bit, but all the 32-bit version of VB have been quite frustrating in terms of getting serial comm to work as anticipated.

Rob already answered your questions, but I did want to touch on the following...

"The data sent or received by UC is in HEX format. Keeping this in mind, which of the InputMode property(comInputModeText or comInputModeBinary)should be chosen ?"

I'm not sure what you mean by the UC sending/receiving in "hex" format. Anything can be represented as hex.

The general rule is that if your VB app will be expecting data BYTES outside of the range of 32-127 (decimal), use binary mode. I personally ALWAYS use binary mode. It's the closest thing to "complete control" you can get with VB in respect to serial communication.

Craig Steiner