Thanks for the help. I was assuming there was a way to stop a read operation before it times out, but since that function apparently does not exist, I wrote the program a little differently. I wanted to be able to end the program with a stop button but that read opertation hung everything up. The way I fixed it was to wire the read operation in a while loop and configure the serial port with a 250 ms timeout. In the loop, I read the error cluster and tested for the timeout code. If the code was there and the stop button was not pressed, the loop tried to read again. If the stop button was pressed, it would clear the error and exit. If that loop was a successful read and there was no error, the loop would exit and the program could continue. Th
anks for the input.