MB5904D-G - 4-Port Industrial Modbus Serial Gigabit Fiber Modbus TCP Gateway: DB9


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MPN: 1P1MB5904DG001G

Manufacturer: Atop Technologies Inc.

Delivery: Ships within 6-7 weeks
Qualifies for Free shipping to the US

Serial Connector & Isolation Options

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Product Information

Product Description

Diverse Hardware Infrastructure
Modbus Gateway supports the four most commonly used communication standards, RS-232/485/422, and Ethernet. The ease-of use configuration utility provided with Modbus Gateway can quickly select the hardware  interface , and easily switch to the existing communication infrastructure. Industrial EMC protection and wide temperature operation capability make MB5904D ready for every mission. And if cabling is an issue, the PoE-powered version can allow MB5904D to be powered through PoE.

Advanced embedded security and advanced features
MB5904D Modbus Gateway supports OpenVPN and IPsec VPN encryption, allowing you to safely use the device over the internet without worrying about malicious attacks, data sniffing or unintentional remote control of your Modbus slaves. On your LAN, RSTP protocol will provide an additional layer of security in case of link losses.

Switching between Modbus Protocols
Modbus Gateway supports the standard Modbus protocol and is capable of converting any Modbus protocols between Modbus TCP, Modbus RTU, and Modbus ASCII for all supported hardware interfaces. All of this, in bidirectional mode: Ethernet and Serial ends can be selected for either master or slave Modbus ID Routing. Modbus Gateway supports various types of hardware communication interfaces, Modbus protocol conversion, and Modbus ID routing. Therefore the Modbus Gateway can integrate your existing and complex Modbus hardware configuration into a simple network that can be easily managed.



Order Summary

 SKU Serial Connector Isolation Manufacturer Part # (MPN)
GC_ATOP-MB5904D-4P-G-TB-SFP TB5 No 1P1MB5904DG002G
GC-ATOP-MB5904D-4P-G-SIS-SFP TB5 Isolation 1P1MB5904DG003G


  • Industrial EMC protection, wide temperature operation, -40°C ~ 85°C (-40°F ~ 185°F)
  • 2 Fast-Ethernet ports or 100/1000 SFP slots
  • 4 Software-selectable RS-232/RS-485/RS-422 serial ports, up to 921kbps
  • Bi-Directional Modbus TCP/RTU/ASCII conversion from Serial to Ethernet and vice-versa, VirtualCOM support, advanced Modbus Options available
  • Isolated Redundant 12~48 VDC Power Inputs
  • Embedded security with PPTP, IPsec or OpenVPN (client/server)
  • Configuration via Web Browser/ Serial Console/ Telnet Console/ Utility
  • Rugged metal case with wall or DIN-Rail mount

Documents and Drivers


MB5904D Series Datasheet

MB5904D Series User Manual

MB5904D Series Hardware Installation Guide

MB5904D UKCA-Declaration of Conformity


Network Interface


  • IEEE 802.3u for 100Base-X 
  • IEEE 802.3z for 1000Base-X 

LAN Mode:  Dual Subnets or Network Redundancy

Connector Ports:  2x 100/1000 Base-X SFP Slots 

Serial Connector

1x2 5 pin 3.81mm Terminal Block, or D-sub9 connector

Serial Ports


Serial Mode

RS-232/422/485, software selectable

Serial Baud Rate

1,200~921,600 bps

Serial Parity

None, Odd, Even

Serial Data Bits


Serial Stop Bits


Serial Isolation

2 KV

USB Ports


USB Speed

USB 2.0

USB Connector

USB A Type


IPv4, ICMP, TCP, UDP, DHCP Client, SNMPv1,v2c,v3, HTTP, HTTPS, Telnet, RFC2217, RSTP, Security via PPTP, OpenVPN Client/Server or IPsec (peer-to-peer or peer-to-side) with up to 37.9Mbps VPN throughput,SMTP/TLS


Atop Management Utility, Web UI, Telnet


Windows/Linux redirection software

Modbus Gateway Supported Modes

Ethernet: Modbus TCP Server/Client(or VCOM)
Serial: Modbus RTU/ASCII (master/slave)

Maximum number of Modbus clients/slaves

Modbus TCP: Maximum 16 clients; Maximum 32 slave connections

Power Input Voltage

Dual 12 - 48VDC

Power Input Current

0.65 A @ 12 VDC

Power Consumption

Approximately 8 W (Max)

Power Connector

7-Pin 5.08mm Lockable Terminal Block

Power Redundancy


Reverse Polarity Protection


Power Relay Ourput

1A @ 30 VDC (normal open)


IP30 SPCC housing


54 x 145 x 113 mm  (2.1 x 5.1 x 4.4 in)


1000g (2.2 lbs)



Reset Button



Operating:  -40°C ~ 85°C (-40°F ~ 185°F)

Storage:  -40°C ~ 85°C (-40°F ~ 185°F)

Ambient Relative Humidity: 5%~95%, 55°C (Non-condensing)

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