MAX3232 RS232 to TTL Serial Converter Module DB9 3.3V 5V - Image 1
MAX3232 RS232 to TTL Serial Converter Module DB9 3.3V 5V - Image 2
MAX3232 RS232 to TTL Serial Converter Module DB9 3.3V 5V - Image 3
MAX3232 RS232 to TTL Serial Converter Module DB9 3.3V 5V - Image 4
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MAX3232 RS232 to TTL Serial Converter Module DB9 3.3V 5V

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Description

šŸ” MAX3232 RS232 to TTL Serial Converter Module DB9 3.3Vā€“5V | AuscomTech

The MAX3232 RS232 to TTL Serial Converter Module provides reliable, bidirectional serial communication between RS232 devices and TTL-level microcontrollers.

Built around the industry-standard MAX3232 IC, this module supports both 3.3V and 5V logic, making it ideal for interfacing MCUs, PLCs, and embedded systems with legacy RS232 equipment via a secure DB9 connector. Its low power consumption and high data rate ensure stable operation in development, industrial, and field applications.

ā­ Key Features

šŸ§  MAX3232 Level Conversion IC
Trusted RS232 transceiver ensures stable and reliable voltage level shifting.

āš” 3.3V & 5V Logic Compatible
Works seamlessly with modern microcontrollers and mixed-voltage systems.

šŸ“” High-Speed Serial Communication
Supports data rates up to 250 kbit/s for efficient RS232 data transfer.

šŸ”Œ DB9 RS232 Connector
Industry-standard DB9 interface provides a secure and robust connection to RS232 devices.

šŸ”‹ Low Power Operation
Consumes less than 1mA idle current and approximately 6mA during operation.

šŸ› ļø Easy MCU Integration
Clearly labelled TXD, RXD, VCC, and GND pins simplify wiring and setup.

šŸ“Š Technical Specifications

Conversion Type: RS232 ā†” TTL
IC: MAX3232
Logic Voltage: 3.3V / 5V
RS232 Connector: DB9
Max Data Rate: Up to 250 kbit/s
Idle Current: < 1mA
Operating Current: ~6mA
Interfaces: TXD, RXD, VCC, GND
Power Source: External supply via VCC

āš ļø Important Notes

ā€¢ RS232 signal levels differ from TTL ā€” this module is required for safe interfacing
ā€¢ Ensure correct TX/RX crossover when wiring to microcontrollers
ā€¢ Not suitable for USB serial communication (USB ā‰  RS232)

šŸ§© Compatible With

ā€¢ PLC systems
ā€¢ STM32 microcontrollers
ā€¢ ESP32 / ESP8266
ā€¢ Arduino (with 3.3V or 5V logic)
ā€¢ STC, NXP, Renesas, NEC MCUs
ā€¢ Embedded Linux boards with UART
ā€¢ Industrial RS232 devices

āš™ļø Typical Applications

ā€¢ RS232 device interfacing
ā€¢ PLC and industrial automation communication
ā€¢ Embedded system debugging
ā€¢ Legacy equipment integration
ā€¢ Serial data logging
ā€¢ MCU-to-RS232 protocol testing

šŸ“¦ Package Includes

ā€¢ 1 Ɨ MAX3232 RS232 to TTL Serial Converter Module with DB9 Connector

šŸ“Œ Code Examples & Usage ā€“ MAX3232 RS232 to TTL Serial Converter (DB9)

šŸ“‹ Overview

The MAX3232 board converts between:

āœ” RS-232 voltage levels (Ā±12 V, DB9 connector)
and
āœ” TTL logic levels (3.3 V or 5 V) appropriate for microcontrollers

This makes it easy to connect:

  • Old computers/terminals

  • Serial sensors and instruments

  • Modems / barcode scanners

  • PLCs and industrial gear

  • GPS modules (if they use proper RS-232 levels)

You can use it with:

šŸ“Œ Arduino (5 V TTL)
šŸ“Œ ESP32 / 3.3 V microcontrollers
šŸ“Œ Raspberry Pi (3.3 V UART)

šŸ”Œ Wiring ā€“ MAX3232 Module

DB9 RS-232 Side

Connect the external RS-232 device (e.g., PC, PLC, CNC controller) to the DB9 female connector.

The most common pins youā€™ll use are:

DB9 Pin Signal Notes
Pin 2 RXD Receive data (to MAX3232)
Pin 3 TXD Transmit data (from MAX3232)
Pin 5 GND Common ground

Other pins (RTS/CTS) may be present depending on your DB9 cable/device.

TTL Side (Microcontroller)

MAX3232 Pin Connect To MCU
VCC 3.3 V or 5 V (match MCU logic)
GND MCU GND
TXO MCU RX (UART receive pin)
RXI MCU TX (UART transmit pin)

āš  Note: Do not power with >5V if using a 3.3 V device ā€” check your MCU logic voltage and jumper selection!

šŸ“Œ Arduino Example ā€“ Serial Bridge

This example reads data from the RS-232 device and prints it to the Arduino Serial Monitor.

Wiring:

  • MAX3232 VCC ā†’ 5V

  • MAX3232 GND ā†’ GND

  • MAX3232 TXO ā†’ Pin 0 (RX)

  • MAX3232 RXI ā†’ Pin 1 (TX)

On boards with a USB-to-Serial chip (like Uno), this serial mapping works best with Serial1 or a software serial port so you can still use USB for debug.

void setup() {
Serial.begin(9600); // USB Serial for monitor
Serial1.begin(9600); // Hardware serial for RS-232
Serial.println("MAX3232 Serial Bridge Ready");
}void loop() {
if (Serial1.available()) {
char c = Serial1.read();
Serial.write(c); // Show incoming RS-232 data on Serial Monitor
}
if (Serial.available()) {
char c = Serial.read();
Serial1.write(c); // Send data from Serial Monitor back to RS-232
}
}

This turns your Arduino into a simple serial bridge / monitor.

šŸ”§ ESP32 Example ā€“ RS-232 to USB Logger

ESP32 uses multiple hardware serial ports, so you can connect Serial2 to MAX3232:

Wiring:

  • MAX3232 VCC ā†’ 3.3V

  • MAX3232 GND ā†’ GND

  • MAX3232 TXO ā†’ GPIO16 (RX2)

  • MAX3232 RXI ā†’ GPIO17 (TX2)

void setup() {
Serial.begin(115200); // For USB Monitor
Serial2.begin(9600, SERIAL_8N1, 16, 17); // RX2, TX2
Serial.println("ESP32 RS-232 via MAX3232");
}void loop() {
while (Serial2.available()) {
Serial.write(Serial2.read());
}
while (Serial.available()) {
Serial2.write(Serial.read());
}
}

This setup lets you monitor RS-232 traffic via the Serial Monitor and send commands.

šŸ Raspberry Pi Example ā€“ Read from RS-232 Device

Raspberry Pi UART pins operate at 3.3 V TTL, so this module works well.

Wiring:

  • MAX3232 VCC ā†’ 3.3 V

  • MAX3232 GND ā†’ GND

  • MAX3232 TXO ā†’ Pi RX (GPIO15)

  • MAX3232 RXI ā†’ Pi TX (GPIO14)

Python Example (PySerial)

import serial

ser = serial.Serial(
port=‘/dev/serial0’, # or ‘/dev/ttyAMA0’ depending on Pi model
baudrate=9600,
timeout=1
)

while True:
data = ser.readline()
if data:
print(data.decode(‘utf-8’, errors=‘ignore’))

Use this to read data from serial sensors or industrial gear via RS-232.

šŸ§  Notes & Tips

āœ” Ensure the MAX3232 board is powered at the correct voltage for your MCU ā€” many boards have jumpers for 3.3 V/5 V selection.
āœ” RS-232 ā€œHIGHā€ and ā€œLOWā€ are inverted compared to TTL. The MAX3232 handles this inversion internally.
āœ” DB9 connectors can be wired DTE or DCE ā€” if you get twisted TX/RX behavior, try using a null modem adapter.
āœ” For industrial gear, confirm the handshake pins (CTS/RTS) if hardware flow control is needed ā€” many microcontroller sketches donā€™t use them.

Additional information

Weight 40 g
Dimensions 260 × 160 × 20 mm

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