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ESCPOS.md

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ESC/POS

Technical notes for implementing ESC/POS commands.

Basics

What is it

General structure

  • Commands are typically sent over a TCP/IP or Serial interface

  • ESC/POS data and commands are simply sent as plain text (ASCII), with line breaks

  • Each line is executed/interpreted as it comes in, in order

  • To print text, you simply send a text line with a line break

  • The ESC or GS characters (ASCII 27 and 29) denote the start of a command

  • Command reference: https://reference.epson-biz.com/modules/ref_escpos/index.php?content_id=72#commands

Weird things

Italics etc

  • The official Epson docs don't have ESC 4 or ESC 5 listed at all (no reference to italics anywhere).

  • The Pyramid ESC/POS docs list ESC 4 as a command with an n parameter for off/on toggle.

  • The node-escpos library I'm testing sends ESC 4 to turn italics on, and ESC 5 to turn italics off, but both with no params

  • The Epson FX commands list also lists ESC 4 as "Select italic mode" and ESC 5 as "Cancel italic mode", but also lists "ESC E" and "ESC F" as emphasised mode on/off which conflicts with modern docs

  • My best guess: Italics are probably not supported in modern ESC/POS. Pyramid's implementation may be vendor specific. Epson FX docs are really old (dot matrix era) and probably not a good reference. node-escpos may have made a mistake. In fact every esc/pos software library seems to reference old and deprecated commands.

  • Conclusion: This is basically hardware specific there is no universal answer