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c#.netserial-porthardware-interface

Receiving Invalid Data from Serial Port using SerialPort.ReadExisting()

I have written a program in .NET that listens to a particular Serial Port and processes the data that is being received. I wrote a test program using com0com (the Null-modem emulator) and my program was working fine. I even tested it with HyperTerminal and that seemed to work fine too.
However when I interfaced the software with the original device (an output received from a control system), the data received was garbled. It contained special characters. The same device when connected with Hyper Terminal produced the desired output. I changed the baud rates, parity etc but the data received was the same set of garbage characters.
I have used the DataReceived event of the SerialPort component and used the following line of code to capture data:

    string data = portRecieve.ReadExisting();

Can somebody tell me where am i missing out? In the current environment, the output from the device is directly connected with a dot matrix printer which prints whatever is received on the port. The printer seems to catch what is being sent but my code couldn't.
If you ever encountered a similar scenario, Please share your findings.
Thanks

Solution

  • I can think of the following reasons why the data might apperar garbled:

    • If there is a bad physical connection, you can sometimes just get garbage (rather than nothing at all). Try unplugging and replugging the leads - and check that you have the correct lead (e.g. do you need a nullmodem?). It looks as though you have this covered by checking in HyperTerminal.

    • If the baud rate, stop bits, parity are not correct - sounds like you have this one covered

    • You are trying to receive the data as a string. If it is not sent as plain text, or if your encoding is wrong, then it could easily appear garbage-like. Try using a binary receive and examine the raw data that you are receiving. This will tell you whether the data is just wrong or the .net conversion is screwing it up - eliminate the middle man!