> 
> Before you go on and flag my question as a duplicate, believe me, its
>  not. I have gone through virtually every solution provided here and I
>  still can't get to get my app to work, so please will you just be nice
>  and take some time to help me.
> 
> 
> 

Scenario: I have a Zebra RW 420 thermal printer which I would like to use for printing vouchers with a QR Code on them. I am using C# and have followed all the help as given by [Scott Chamberlain here](https://stackoverflow.com/questions/25669403/how-to-send-a-raw-zpl-to-zebra-printer-using-c-sharp-via-usb) and the [code here](http://support.microsoft.com/kb/322091) for sending the commands to the printer. I have the EPL2 manual as well as the CPCL, and ZPL reference manuals with a whole lot of stuff on how to format my commands.

Problem:
All the commands I am sending are either printing as plain text replicas of the commands or the printer just hangs with the small message icon showing on its display. I have tried sending the same commands using the Zebra Utilitis and still getting the same result as with my sample app.
Below is the code snippets I have, please do advise me if there are any reference libraries I may require to get this to work.

```
private void btnPrint_Click(object sender, RoutedEventArgs e)
    {
        string s = "! 0 200 200 500 1\nB QR 10 100 M 2 U 10\nMA,QR code ABC123\nENDQR\nFORM\nPRINT"; 

```

// Have also tried \r\n for the line feeds with the same result.

```
        // Allow the user to select a printer.
        PrintDialog pd = new PrintDialog();

        if ((bool)pd.ShowDialog())
        {
            var bytes = Encoding.ASCII.GetBytes(s);
            // Send a printer-specific to the printer.
            RawPrinterHelper.SendBytesToPrinter(pd.PrintQueue.FullName, bytes, bytes.Length);
        }
    }

```

PrinterHelper class as modified by [Scott here](https://stackoverflow.com/questions/25669403/how-to-send-a-raw-zpl-to-zebra-printer-using-c-sharp-via-usb)

```
public class RawPrinterHelper
{
    // Structure and API declarions:
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    public class DOCINFOA
    {
        [MarshalAs(UnmanagedType.LPStr)] public string pDocName;
        [MarshalAs(UnmanagedType.LPStr)] public string pOutputFile;
        [MarshalAs(UnmanagedType.LPStr)] public string pDataType;
    }

    [DllImport("winspool.Drv", EntryPoint = "OpenPrinterA", SetLastError = true, CharSet = CharSet.Ansi,
        ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter,
        IntPtr pd);

    [DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, ExactSpelling = true,
        CallingConvention = CallingConvention.StdCall)]
    public static extern bool ClosePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "StartDocPrinterA", SetLastError = true, CharSet = CharSet.Ansi,
        ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool StartDocPrinter(IntPtr hPrinter, Int32 level,
        [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

    [DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, ExactSpelling = true,
        CallingConvention = CallingConvention.StdCall)]
    public static extern bool EndDocPrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, ExactSpelling = true,
        CallingConvention = CallingConvention.StdCall)]
    public static extern bool StartPagePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, ExactSpelling = true,
        CallingConvention = CallingConvention.StdCall)]
    public static extern bool EndPagePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, ExactSpelling = true,
        CallingConvention = CallingConvention.StdCall)]
    public static extern bool WritePrinter(IntPtr hPrinter, byte[] pBytes, Int32 dwCount, out Int32 dwWritten);

    // SendBytesToPrinter()
    // When the function is given a printer name and an unmanaged array
    // of bytes, the function sends those bytes to the print queue.
    // Returns true on success, false on failure.
    public static bool SendBytesToPrinter(string szPrinterName, byte[] pBytes, Int32 dwCount)
    {
        Int32 dwError = 0, dwWritten = 0;
        IntPtr hPrinter = new IntPtr(0);
        DOCINFOA di = new DOCINFOA();
        bool bSuccess = false; // Assume failure unless you specifically succeed.

        di.pDocName = "Zebra Label";
        di.pDataType = "RAW";

        // Open the printer.
        if (OpenPrinter(szPrinterName.Normalize(), out hPrinter, IntPtr.Zero))
        {
            // Start a document.
            if (StartDocPrinter(hPrinter, 1, di))
            {
                // Start a page.
                if (StartPagePrinter(hPrinter))
                {
                    // Write your bytes.
                    bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
                    EndPagePrinter(hPrinter);
                }
                EndDocPrinter(hPrinter);
            }
            ClosePrinter(hPrinter);
        }
        // If you did not succeed, GetLastError may give more information
        // about why not.
        if (bSuccess == false)
        {
            dwError = Marshal.GetLastWin32Error();
            throw new Win32Exception(dwError);
        }
        return bSuccess;
    }

```

}