T7-US Thermal Printer with RS232 Interface on Raspberry Pi 4

T7-US Thermal Printer with RS232 Interface on Raspberry Pi 4

Overview

The T7-US thermal printer i bought has an USB and RS232 serial interface. This guide provides step-by-step instructions to set up and use the T7-US printer with a Raspberry Pi 4 Model B via a MAX3232 RS232-to-TTL converter.

Note: This documentation is part of my thesis research. I initially purchased the T7-US RS232 version due to a lack of research, thinking it would work directly with the Raspberry Pi 4. However, I later realized that the TTL version would have been a better choice… lesson learned!

Hardware I Used

• T7-US Thermal Printer (RS232 version)
• Raspberry Pi 4 Model B
• MAX3232 RS232-to-TTL Converter
• 9V 3A Power Adapter for the printer
• 12V DC Female Connector (used to expose 9V VCC and GND)
• Jumper Wires

T7-US Thermal Printer (RS232+USB)

MAX3232 (RS232) DB9 Female Pin

Wiring Diagram

1️⃣ Raspberry Pi 4 ↔ MAX3232 (TTL Side)

Raspberry Pi GPIO	MAX3232 Pin (TTL Side)	Description
GPIO 14 (TXD, Pin 8)	TXD	Pi TX → MAX3232 TX
GPIO 15 (RXD, Pin 10)	RXD	Pi RX ← MAX3232 RX
5V	VCC (5V)	Power MAX3232
GND	GND	Common Ground

2️⃣ MAX3232 DB9 (RS232 Side) ↔ T7-US Printer

MAX3232 Pin [DB9 Female] (RS232 Side)	T7-US Printer Pin	Description
TXD (Pin 3)	RX	MAX3232 TX → Printer RX
RXD (Pin 4)	TX	MAX3232 RX ← Printer TX
GND (Pin 1)	GND	Common Ground

3️⃣ Powering the Printer

T7-US Printer Pin	Power Source
VIN (9V)	9V 3A Power Adapter
GND	Common Ground

Thesis Project

This setup is part of my thesis project, documenting the integration of the T7-US Thermal Printer with the Raspberry Pi 4 using an RS232 interface and MAX3232 converter.