Sending data to USB printer in Delphi

Question

How do I send text commands to a printer connected in the USB port using Delphi?

I have a Zebra TLP2844 printer and want to program a direct communication with it.

Answer 1

You use the WinAPI function Escape, passing it the Printer.Canvas.Handle as the first parameter and PASSTHROUGH as the nEscape parameter.

var
  YourCommand: String;
begin
  YourComamnd := 'Your command here';

  if Escape(Printer.Canvas.Handle, 
                PASSTHROUGH, 
                Length(YourCommand), 
                PChar(YourCommand), 
                nil) <> 0 then
    // Handle return value (listed in docs link above)
  else
    // send next command 

Escape is defined in the Windows unit. Note you have to call Printer.StartPage before using this function in order to prepare the printer driver to receive content.