Simon Lee:

In order to make the MSCOMM work correctly you have to configure the port to operate in binary mode. Note also that once you put the port in binary mode that process of receiving characters is just a little different from ASCII mode.

I learned all I needed to know about VB serial communications from a book on RS232 that contains a wealth of information. It is especially valuable to a Visual Basic programmer, particulary if you like to prototype in Visual Basic on your PC before moving the work over to your 8051/52 embedded platform. The book is called Visual Basic: Programmers Guide to Serial Communications. The author is Richard Grier. ISBN 1-890422-25-8. You can look at and order it at www.mabry.com.

Here is code I wrote that you can download that shows using MSCOMM in binary mode. Complete VB Applett with MSCOMM.

Good Luck
Michael Karas