I have a piece of calibration equipment that I'm attempting to write a desktop application to read from its Com port. The calibration equipment will either send its datastream when a button is pressed on its front panel, or when RTS is asserted. The manual states it may service up to 5 requests per second. If RTS is asserted (and remains so), it will only send one reading, it has to be cancelled and reasserted again for the next one. Fairly regularly I get gobbledegook in the textbox - but I'm sure its because I'm not reading the incomming stream properly. I have to use an 'OnComm' event for the times the front panel button is pressed. I've never quite understood the triggering of OnComm: instuctions in the OnComm may be being executed as more data is arriving in the buffer(?) Parameters are fixed at 1200,8,N,1 'TWA1000Sim' is a simulator of the calibration equipment and behaves exactly the same. (The big 'O' button simulates the on/off switch ) I compile this for the Device and run it on my TDS Recon connected via RS232 to the desktop. It will compile for the desktop too.