Both the prolific converter and the native serial port work just fine in other programs such as puTTY, procomm, or the manufacturer software. The port settings are correct, /None/XonXoff, as per manufacturer and personal experience. I previously used ReadExisting() and ReadByte(), but the result was the same for each, so I went back to ReadLine, because it works best with the data I'm receiving (80 characters followed by EOL) My current method of retrieving data is via DataReceivedHandler event and ReadLine(). Displayed just fine if I strip the bad characters, but that's a cheap hack when something else is clearly wrong.Īn example of expected data, and received data: //Expected:įIRE ALARM MAGNET ELEVATOR SHAFT HOISTWAYĮLEVATOR SHAFT Z111 HEAT(fixed) 09:34:19A FRI L02D041 Using the prolific converter, it 'works' in that I get all the data I expect - with the addition of a 3F/? between every single character. Usually not even the right length of nonsense. And now my data is garbled nonsense (mostly 3F/?.) Occasionally I will see the correct character, but it's mostly nonsense. Then I ported it over to some work laptops, which are Dell's with native com ports. I occasionally got a random 3F/? in the data when connected to one of the two types of FACPs, but I figured that was just the converter acting up, so I just stripped them from the output. I have a program that communicates one-way (receive only) with some equipment (fire alarm control panels to be specific.) When I wrote the program, it was done on PC that doesn't have a native serial port, so I used a prolific serial->usb dongle. I am not entirely sure this if this is a problem with my code, or a hardware problem.

Prolific usb to serial comm port 1