UWP C# UART RS485 Polling Issue RRS feed

  • Question

  • Hi, I have my UART for RS485 using a FTDI USB to 485 cable connected to Raspberry Pi on Windows IoT Core. I set a dispatchertimer at every 1second to transmit polling to respective field devices. I am able to tx and rx the 485 data with no problem. However, after the polling loop to about 20 times it just crash and exited the debug mode. I used try & catch to trap the exception but could not get it. However, i manage to read the error message at the debug output pane - The program [0xBB0] PwD.exe' has exited with code -1073741811 (0xc000000d).

    I am not sure what caused the problem and where did I do wrong?

    Please help. Thanks.

    private void PollTimer_Tick(object sender, object e)
            if (pollCounter <= maxDevice)
                var a = pollCounter | 0x80;
                TxAdr = Convert.ToByte(a);
                TxCmd = TxPoll;
            else pollCounter = 0;
     private async void TxPollCard()
            if (serialPort != null)
                List<byte> data = new List<byte>();
                TxChkSum = 0;
                foreach (byte a in data)
                    TxChkSum += a;
                TxChkSum = (byte)(TxChkSum - 0x80);
                    // Create the DataWriter object and attach to OutputStream
                    dataWriteObject = new DataWriter(serialPort.OutputStream);
                    Task<UInt32> storeAsyncTask;
                    // Launch an async task to complete the write operation
                    storeAsyncTask = dataWriteObject.StoreAsync().AsTask();
                    UInt32 bytesWritten = await storeAsyncTask;
                catch (Exception ex)
                    await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
                        MainStatusDisplay.Text = ex.Message;
                await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
                    MainStatusDisplay.Text = "No UART port found";

    • Edited by mylim Wednesday, November 11, 2020 7:42 AM
    • Moved by CoolDadTx Wednesday, November 11, 2020 2:59 PM Not C# related
    Wednesday, November 11, 2020 7:25 AM

All replies

  • Hi mylim,

    Thank you for posting here.

    Since this thread is related to UWP, so I suggest that you can ask this question in Microsoft Q&A.

    Best Regards,


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    Wednesday, November 11, 2020 8:47 AM
  • Thanks.
    Wednesday, November 11, 2020 9:50 AM