CODEWITHSUNDEEP
c#serial-portzebra-printers
CodeGus
CodeGus

Reputation: 5

Serial communication Zebra GC420t - Not receiving

I'm trying to communicate with the GC420t via serial port in c#.

I need to get the status of the printer.

I want to send the command ~HQES and receive the status.

I'm able to write commands: I've tryied to print succesfully some qrcodes.

But when I write the status info command I don't get any answer.

This is my test code:

//define serial port
static SerialPort _serialPort = new SerialPort("COM7", 9600, Parity.None, 8, StopBits.One);

public Serial()
{
      try
      {
        _serialPort.Open();
        WriteCommand();
        ReadStatus();
      }
      catch (Exception ex)
      {
        _serialPort.Close();
      }
}



public void WriteCommand()
{
      string qrcode = "^XA^FO,20,20^BQ,2,10^FDD03048F,LM,N0123456789,A12AABB,B0006qrcode^FS^XZ";
      string statusInfo = " ~HQES";
      _serialPort.Write(statusInfo);
}

public void ReadStatus()
{
      _serialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
}

private static void DataReceivedHandler(
           object sender,
           SerialDataReceivedEventArgs e)
{
      SerialPort sp = (SerialPort)sender;
      string indata = sp.ReadExisting();
      Console.WriteLine("Data Received:");
      Console.Write(indata);
}

EDIT: It will be fine for me also to be able to get that info on request:

WriteCommand();
int timeout = 3000;
while (timeout > 0)
{
   Thread.Sleep(10);
   timeout--;
   // Timeout
   string status = _serialPort.ReadExisting();
}

Upvotes: 0

Views: 895

Answers (2)

PaulF
PaulF

Reputation: 6773

You should check ifs the printer configured to use any form of handshaking? Particularly XON/XOFF or DTR .

Ref page 24 of User Guide. https://www.uline.com/PDF/IH-7246VND.PDF

In the event the link breaks - the relevant text is

"The printer has a DCE serial communication port for hardware compatibility with legacy 888 printers. The required cable must have a nine-pin "D" type (DB-9P) male connector on one end which plugs into the mating (DB-9S) serial port located on the back of the printer. The other end of this signal interface cable connects to a serial port on the host computer. The cable is a Null-Modem (cross-over signal connections) cable. For pinout information, refer to Appendix A.

The serial port communication settings between the printer and host (typically a PC) must match for reliable communication. The Bits per second (or Baud rate) and Flow control are the most common settings that get changed. The host (typically a Windows PC) needs to have the data Flow control changed to match the printer's default communication method: Hardware and is noted by the Host Handshake setting DTR/Xon/Xoff. This combined hardware (DTR) and software (Xon/Xoff) mode may need to change depending{ upon use with non-Zebra application software or the serial cable variation in use."

Upvotes: 1

Neil
Neil

Reputation: 11889

You need to hook up the DataReceived handler before you make any calls, otherwise it might have answered before you hook it up.

Move ReadStatus up 1 line so that it comes straight after the constructor.

    _serialPort.Open();
    ReadStatus();
    WriteCommand();

Upvotes: 1

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