MAX3485 TTL to RS485 3.3V module with the green three-way bus terminal in the foreground and the four-pin GND, RXD, TXD, VCC header behind

MAX3485 TTL to RS485 Auto Direction Module - 3.3V

$4.49 NZD
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MAX3485 TTL to RS485 3.3V module with the green three-way bus terminal in the foreground and the four-pin GND, RXD, TXD, VCC header behind
  • MAX3485 TTL to RS485 3.3V module with the green three-way bus terminal in the foreground and the four-pin GND, RXD, TXD, VCC header behind
  • Front of the HW-144 RS485 board showing the GND, D-/B, D+/A terminal labels and the VCC, TXD, RXD, GND header labels
  • Underside of the TTL485-V2.0 board with the printed RS485 to TTL pin map and the 120_S termination diagram
  • MAX3485 RS485 module dimensions: PCB approximately 54 mm long and 22 mm wide, excluding header pins
MAX3485 TTL to RS485 Auto Direction Module - 3.3V
SKU: MOD-MAX3485-RS485

MAX3485 TTL to RS485 Auto Direction Module - 3.3V

$4.49 NZD
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Connect a 3.3V microcontroller UART to a two-wire RS485 bus with this MAX3485 module. It runs from 3.3V, so it wires straight to an ESP32, Raspberry Pi Pico or other 3.3V board, and an onboard circuit switches between transmit and receive for you, so no direction-control pin is needed. Using a 5V board such as an Arduino Uno? Choose our MAX13487 5V RS485 module instead.

Specifications

Board markingHW-144
TransceiverMAX3485
Module supply3.3V DC (3.0 to 3.6V)
Logic level3.3V UART
TTL interfaceVCC, TXD, RXD, GND
RS485 interfaceD+/A, D-/B, GND
Bus modeTwo-wire half duplex
Direction controlAutomatic
Bus loading1 unit load, up to 32 nodes
Status LEDsPower, TXD and RXD
Termination120 ohm via 120_S bridge
Board sizeAbout 54 x 22 mm

Datasheets

Full technical datasheet PDF

What's in the box

1×
MAX3485 TTL to RS485 module

Red HW-144 board with a fitted right-angle 4-pin header and a green 3-way screw terminal.

Great for

Reading a Modbus RTU energy meter from an ESP32
Linking two Raspberry Pi Picos over a long cable
Polling RS485 sensors from a 3.3V controller
Talking to a VFD or PLC serial port

Wiring & getting started

  1. Connect power with the circuit off

    Connect a regulated 3.3V supply to VCC and join the controller and module grounds. Do not power it from 5V.

  2. Connect the UART

    Connect controller TX to TXD and controller RX to RXD. The module switches between sending and receiving by itself.

  3. Connect the RS485 bus

    Connect D+/A to the remote A or + terminal and D-/B to the remote B or - terminal. Keep the polarity the same along the whole bus.

  4. Set termination and start slow

    Bridge 120_S only when this module is at a physical end of the cable. Start at 9600 baud and raise the speed once replies are reliable.

Frequently Asked Questions

Answers to the questions buyers ask most.

Can I use this module with a 5V Arduino?
Use our MAX13487 5V RS485 module for a 5V board instead. This module must be powered from 3.3V, and its RXD output is 3.3V logic.
Which boards does it suit?
3.3V boards such as the ESP32, Raspberry Pi Pico, STM32 and Raspberry Pi. Power VCC from the board's 3.3V rail and connect TX, RX and ground.
Do I need a direction-control pin?
No. The board has no DE or RE pin. An onboard circuit switches the transceiver between transmit and receive, so only TXD, RXD, VCC and ground connect to the controller.
What baud rate can it use?
The MAX3485 transceiver is rated to 10 Mbps, but the onboard direction circuit sets the practical limit. Start at 9600 baud, the most common Modbus RTU rate, and raise it only after replies are reliable.
How many devices can share the bus?
Up to 32 devices of one unit load each, including this module. Wire them along one cable and keep A and B polarity the same at every device.
When should I enable the 120 ohm termination?
Bridge 120_S only when this module sits at a physical end of the RS485 cable. Leave it open at modules in the middle of the bus.
Is this module galvanically isolated?
No. The controller side and the RS485 side share ground. Use an isolated RS485 interface where isolation is required.

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