Industrial Modbus TCP to 4 port Serial (232,422,485) RTU/ASCII Gateway


Antaira Technologies’ STM-604C is an industrial MODBUS gateway that allows legacy MODBUS RTU/ASCII devices to operate on a MODBUS TCP network. It can be configured for either MODBUS serial master or slave to communicate with MODBUS TCP’s slave or master. The STM-604C features two independent Ethernet ports and MAC addresses to provide redundancy and reliability. These devices provide an economical way of connecting MODBUS RTU/ASCII devices to networks accessible anywhere in the world.


Ambient Relative Humidity 5% to 95%, (non-condensing)
Baud Rate 50 bps ~ 921.6 kbps, any baud rate setting
Configuration Windows Utility, Telnet Console, Web Browser
Data Bits 5, 6, 7, 8
Dimensions 55 x 140 x 95 mm (2.17″ x 5.51″ x 3.74″)
EMC CE, FCC Part 15 Subpart B (Class A)
Ethernet Port 2 with independent IP and MAC addresses
Ethernet Port 2*10/100T(X) auto negotiation speed, Full/Half duplex mode, and auto MDI/MDI-X connection
Flow Control XON/XOFF, RTS/CTS
Green RoHS Compliant
Hazardous Location UL/cUL (Class 1, Division 2, Groups A, B, C and D)
Housing Metal with solid mounting hardware
Input Voltage 12 to 48VDC, Redundant Inputs
LED Indicators Link / Act
LED Indicators System: Power, System Status
LAN: Speed, Link/Active
Serial: Tx, Rx
Mounting DIN-Rail Mounting, Wall Mounting
Operating Temperature -10° ~ 60°C
Operation Mode Modbus RTU Master/Slave mode
Modbus ASCII Master/Slave mode
OS Support 32-bit/64-bit Windows XP/Vista/7/8/8.1/10, Windows Server 2003/2008/2008 R2/2012/2012 R2
Overload Current Protection Present
Parity None, Odd, Even, Space, Mark
Port Type RS-232/422/485, software selectable
Power Connection Terminal block
Power Consumption 3.2 W
Processing Type Store and Forward
Protection 15 KV ESD for all signals
Protocols CSMA/CD
Reboot Trigger Built-in WDT (watchdog timer)
Reverse Polarity Protection Present
Serial Ports 4 – DB9 male
Serial Signals RS-232: TxD, RxD, CTS, RTS, DCD, RI, GND
RS-422: TxD+, TxD-, RxD+, RxD-, GND
RS-485: Data+, Data-, GND
Standards IEEE 802.3 10Base-T Ethernet
IEEE 802.3u 100Base-TX Fast Ethernet
Stop Bits 1, 2
Storage Temperature -40 ~ 85°C
Utility Software Antaira Device Configuration Utility
Warranty 5 Years
Weight 1.22 lbs (0.555 kg)



  • 2*10/100 Mbps Ethernet Ports for LAN Redundancy
  • Integrates Modbus TCP and Modbus RTU/ASCII Networks
  • Supports Up to 921.6 kbps and Any Baud Rate Setting
  • Supports Up to 16 Connections per Serial Port Under Modbus Master Mode and 32
  • Sessions Under Modbus Slave Mode
  • Software-selectable RS-232/422/485 Communication
  • Automatic RS-485 Data Flow Control
  • Redundant Power Input: 12~48VDC
  • Power Polarity Reverse Protection
  • Overload Current Protection
  • DIN-Rail or Wall Mountable
  • Standard Temperature Model
  • 5-Year Warranty