>>
>>What's the value of the comm port variable?
>
>COM3
>
>>> And does the port exist?
>
>Its what's sending this :-)
>
Hi Harry,

Let me check my code at home. If WriteFile() is returning 1 then it's succeeding. If I understood your previous post correctly, then the problem with opening the port isn't a problem.

BTW, you asked about the #DEFINE statements earlier. These are defined constants. Their purpose is to make the code more readable. GENERIC_READ is a lot easier to understand than 0x80000000.