For Downloads

Data Sheet – User Manual – Other Documents – Certificates


Setup Software

Testing Software

For Purchase

Call / WhatsApp / Telegram: +91 8148834200

For Technical Support

Call / WhatsApp / Telegram: +91 8148834211

USR-DR404 is a Din Rail RS485 to WiFi converter which can realizes bidirectional transparent transmission between RS485 and WiFi / Ethernet.
● 1-port RS485 to 802.11 a/b/g/n WLAN Serial Device Server
● Links serial and Ethernet devices to an IEEE 802.11a/b/g/n network
● Supports TCP server/client, UDP server/client,https client, Virtual COM
● Supports Modbus RTU to Modbus TCP
● Supports multiple networking mode with 1 RJ45 ethernet port
● MQTT special firmware (contact sales)



Port Number

1 Ethernet Ports: 1 x WAN/LAN


RX/TX: Max 4K bytes


2KV Electromagnetic isolation for Ethernet port

Speed Rate

10/100Mbps, MDI/MDIX





802.11 b/g/n




802.11b: +19dBm(Max.@11Mbps)

802.11g: +18dBm(Max.@54Mbps)

802.11n: +17dBm(Max.@HT20,MCS7)


User can configure power


802.11b: -89dBm(@11Mbps)

802.11g: -81dBm(@54Mbps)

802.11n: -73dBm(@HT20,MCS7)





485 interface (anti surge, anti thunder, overcurrent protection)

Input Voltage


Operating Temp







Network Mode






Work Mode

Transparent transmission/Serial command/

https Client/Modbus TCP<=>Modbus RTU


AT+ command

Networking Protocol


Max Client Numberin TCP Server Mode



Web server+AT command

Customer application software

Support customize application software


Introduction of DR(Din-Rail)series products

DR(Din-Rail)series products are our newly launched devices which include
serial device server, 4G cellular modem, 4G industrial router and other product
models, Equipped with 35mm din-rail clasp, this products are more suitable for

device connecting internet.
Based on wifi network:USR-DR404

Features of DR404.jpg
Product Detail Of WIFI serial device server USR-DR404

Product Detail

PC + ABS material, light and easy to carry, low cost, high performance,
V0 class flame retardant rating, to ensure the safety

WIFI serial device server USR-DR404 with Din-rail Installation design

Din-rail Installation

Compact size, less space, wide application, Guide buckle, flexible and easy to install,
less management and maintenance, high cost performance.

Fundamental Function of WIFI serial device server USR-DR404

Fundamental Function

Bidirectional Transparent transmission
between RS485 and Wi-Fi / Ethernet

Function Structure introduction of WIFI serial device server USR-DR404,

Function Structure


Work Mode

Transparent Transmission Mode

Data is transmitted transparently between serial port and
Wi-Fi / Ethernet via DR404, enabling data transfer
between serial port device and network device

WIFI serial device server USR-DR404

Serial Command Mode

The user sends data to the server according to the protocol
and can send data to different servers without restarting.

WIFI serial device server USR-DR404

httpsD Client Mode

After the user completes the https header with an AT instruction or
web page setup, DR404 can pass data to or from the https server.

WIFI serial device server USR-DR404

AT Command Mode

Users can query the current status of DR404
or set relevant parameters by sending AT instructions

Features of WIFI serial device server USR-DR404


Modbus Gateways

Mode of transferring data
between Modbus TCP and Modbus RTU.

Socket Distribution

In transparent transmission mode, the serial device
can send data to the specified Socket connection.
Network data for each Socket are sent to
the serial device via the serial port.

Quick Networking Protocol

Mobile phone connect to the AP of DR404,you can directly
set the specified AP to which DR404 connects by querying
surrounding AP’s SSID list through USR-LINK, which is
convenient and fast. You can quickly connect to the Internet
without operating DR404.

Custom Registration Package,
Heartbeat Package

The registry package is used for easy device
identification from the server.

WIFI serial device server USR-DR404 with Hardware Protection function

Hardware Protection

ESD 4 level Electrostatic Discharge Immunity, 3 level Surge Immunity,
EFT 3 level Electrical Fast Transient / Burst Immunity.

WIFI serial device server USR-DR404
WIFI serial device server USR-DR404
WIFI serial device server USR-DR404: Related Production

Packing list

Packing list one serial device server and Wi-Fi antenna, if you need power adapter,
contact our sales.

Application Cases of WIFI serial device server USR-DR404

Application Case

Smart Factory Data Collection and Transmission

Compact wireless device server DR404 is connected to the serial port device in the factory, and the device
operation data is uploaded to the local monitoring platform or USR cloud
platform in real time. Through the monitoring platform, the staff can
dynamically understand the operation of the monitored equipment.

WIFI serial device server USR-DR404

Textile Machinery Factory Data Acquisition and Transmission

Compact size, less space. Equipped with DIN- rail for easy mounted,
The terminal data of the PLC can be quickly uploaded to the monitoring platform,
so that the staff can understand the PLC work in real time.


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Din Rail RS485 to WiFi and Ethernet Converter (DR404)

  • Brand: usr iot
  • Product Code: USR-DR404
  • Availability: Out Of Stock
  • Rs.2,800.00

Tags: din, rail, rs485, wifi, ethernet, converter, DR404