MS2548 TTL to RS485 5V module with the green three-way bus terminal in the foreground and the four-pin GND, RXD, TXD, VCC header behind

MS2548 TTL to RS485 Auto Direction Module - 5V

$4.49 NZD
Skip to product information
MS2548 TTL to RS485 5V module with the green three-way bus terminal in the foreground and the four-pin GND, RXD, TXD, VCC header behind
  • MS2548 TTL to RS485 5V 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, the MS2548 transceiver 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
  • MS2548 RS485 module dimensions: PCB approximately 54 mm long and 22 mm wide, excluding header pins
MS2548 TTL to RS485 Auto Direction Module - 5V
SKU: MOD-MS2548-RS485

MS2548 TTL to RS485 Auto Direction Module - 5V

$4.49 NZD
Order before 7:30am for same-day dispatch 7-day dispatch, excluding public holidays

NZ Post: 1-2 days urban · 2-4 days rural

Shipping from $5.99 urban / $9.99 rural.

Easy 30-day returns · 12-month warranty

Free Urban delivery on orders over $66
Urban $66 Rural $88

Connect a microcontroller UART to a two-wire RS485 bus with this MS2548 module. It runs from 5V, and the MS2548 transceiver switches between transmit and receive by itself, so no direction-control pin is needed. Its TXD and RXD pins use 5V logic, so it wires straight to an Arduino Uno or other 5V board. With a 3.3V board such as an ESP32, add a level shifter on both lines.

Specifications

Board markingHW-144
TransceiverMS2548
Module supply5V DC (4.5 to 5.5V)
Logic level5V UART
TTL interfaceVCC, TXD, RXD, GND
RS485 interfaceD+/A, D-/B, GND
Bus modeTwo-wire half duplex
Direction controlAutomatic, in the transceiver
Bus loading1/4 unit load, up to 128 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×
MS2548 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 Arduino
Talking to a VFD or PLC serial port
Polling RS485 sensors over a long cable
Linking two microcontrollers across a workshop

Wiring & getting started

  1. Connect power with the circuit off

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

  2. Connect the UART

    Connect controller TX to TXD and controller RX to RXD. On a 3.3V board such as an ESP32 or Pico, run both lines through a bidirectional level shifter.

  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 it with an ESP32 or Raspberry Pi Pico?
Yes, with a level shifter. Power the module from 5V and run TXD and RXD through a bidirectional level shifter, because both pins use 5V logic. A 5V board such as an Arduino Uno connects directly.
Will it run from 3.3V?
No. The MS2548 transceiver is rated for 4.5V to 5.5V. Power VCC from a regulated 5V rail.
Do I need a direction-control pin?
No. The MS2548 switches between transmit and receive by itself, so only VCC, TXD, RXD and ground connect to the controller.
What baud rate can it use?
The transceiver is rated to 20 Mbps, but cable length and the automatic switching set the practical limit. Start at 9600 baud, the common Modbus RTU rate, and raise it once replies are reliable.
How many devices can share the bus?
The transceiver is a 1/4 unit load, so up to 128 devices of the same loading can share one bus. 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.

Have a Question About This Product?

Send it through and we will get back to you by email.

Why Buy from NZN

Useful parts, fair prices and someone local to help.

I'm Lukas, an engineering student and maker based in Te Awamutu. NZN grew out of a CNC build that dragged on for months because every missing cable, bolt or electronic part meant another overseas order. I started the shop so Kiwi makers can spend more time building and less time waiting for the next parcel.

More about NZN Electronics

  • Stocked here in New Zealand

    Orders are picked and packed in Te Awamutu and dispatched within 24 hours every day, excluding public holidays. NZ Post target delivery is 1-2 days urban and 2-4 days rural.

  • Fair prices, clearly shown

    Prices are kept competitive and quantity discounts are shown upfront. Free delivery starts at $66 for urban addresses and $88 for rural addresses.

  • 30-day returns and 12-month warranty

    Get in touch if something is not right and we will help sort it.

  • Practical product support

    Ask a product question and get help from a real person in New Zealand who knows the range.

You may also like