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Asked: 2026-05-16T23:20:10+00:00

I am trying to read data from a scale RS232 interface. It sends a

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I am trying to read data from a scale RS232 interface. It sends a continuous ASCII string stream through the Serial Port which I am having trouble getting. I just want to get one line of the data that it is sending out. I guess I assumed that I would use Readline to get the data, but it just locks up the PC when I run it. I think it is trying to get all of the data and won’t stop until the data stops? Here is the code I’m using:

private void button1_Click(object sender, EventArgs e)
    {
        serialPort1.PortName = "COM4";
        serialPort1.BaudRate = 9600;
        serialPort1.DataBits = 8;
        serialPort1.Parity = Parity.None;
        serialPort1.StopBits = StopBits.One;

        //opening the serial port
        serialPort1.Open();

        string str = serialPort1.ReadLine();

        MessageBox.Show(str);

        serialPort1.Close();

    }

Can you help me to determine how to get just one line of the output data and close the connection?

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1 Answer

  1. Editorial Team

    SerialPort.ReadLine is defined to block “up to the first occurrence of a NewLine value”, where NewLine defaults to a line feed. Are you sending a linefeed in your stream? Note that a linefeed character (ASCII 0x0A) is different that a carriage return (ASCII 0x0D) that you might be sending.

    You can redefine the NewLine if needed, or if a line ending doesn’t feel right, you can read up to a given string with SerialPort.ReadTo. You can also set a read timeout.

    You might prefer to read a given number of bytes from the port, rather than a line, with one of the SerialPort.Read overloads.

    If none of this applies, make sure that you’re actually sending data where you think you are – bring up HyperTerminal/TeraTerm/your favorite serial terminal, configure it with the same serial port settings as you’ve used above, and make sure you see the data you expect to see.

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