RawPrinterHelper unable to print Barcode using ESC POS Commands

Question

A relatively simple task is turning into hours of frustration so here goes:

I have various Thermal printers and we print to the using the RawPrinterHelper that Microsoft posted. Usually use a String builder build the string and call the SendStringToPrinter and we have a printed piece of paper.

I'm trying to print a simple barcode via the ESC/POS commands that are supported. WE use these for other functions (cutting, change font sizes) that all works, the barcode refuses to print.

ESC POS Command is : GS k m n d1 d2 … dn m：barcode type e.g. n：barcode length -indicates the number of bar code data bytes d1 the barcode

The question I have is, How do I send the length of the barcode? I believe this where my problem lies.

The code snippet:

StringBuilder print = new StringBuilder();
barcode = "1234567890";
char commandGS = '\x1D';
char linefeed = '\x0A';
char esc = '\x1B';
char commandFontSize = '\x21';
char commandk = '\x6B';
char code128 = '\x69';
print.Append(commandGS);
print.Append(commandk);
print.Append(code128);
print.Append(barcode.Length);
print.Append(barcode);
string printJob = print.ToString();
RawPrinterHelper.SendStringToPrinter(printerName, printJob);

Answer 1

You probably need a byte to represent the length of the barcode rather than the text representation of the length of the barcode.

So instead of

print.Append(barcode.Length);

use

print.Append((char)barcode.Length);

I assume the length does not exceed 255.

Edited to add: You can examine the bytes which you are sending with something like

var bb = Encoding.UTF8.GetBytes(printJob);
bb.ToList().ForEach(x => Console.Write(x.ToString("X2") + " "));

and check that they conform to what you intend to send. You may also want to compare what is sent to something which does work in your current code.