* This is a Tibbo BASIC/C-programmable device and its function depends on the loaded app.
We offer many ready-to-use apps, among them a serial-over-IP (SoI) app, Modbus Gateway app, and Sensor Hub app.

EM203 Serial-to-Ethernet Module

The EM203 is a miniature serial-to-Ethernet (a.k.a. "serial-over-IP" or "SoI") module.

In combination with the RJ203 jack/magnetics front-end (shown), the EM203 forms a complete Ethernet node occupying only 31x20mm (1.22x0.79") of the host board's space.

The EM203 is compatible with Tibbo Device Server Toolkit (TDST) for Windows. TDST includes the Virtual Serial Port Driver (VSPD), which enables you to use the serial port of the module as a remote COM port of your PC. The Linux version of the VSPD is available as well.

Key Features

10/100 Base-T Ethernet port

Mates with the RJ203 jack/magnetics front-end

5V power



  • 10/100Base-T Ethernet port (mates with the RJ203).
  • One UART (CMOS):
    • Baudrates of up to 115,200bps;
    • None/even/odd/mark/space parity modes;
    • 7 or 8 bits/character;
    • Full-duplex mode with RTS/CTS flow control;
    • Half-duplex mode with direction control.
  • Four status LEDs onboard:
    • Green and red main status LEDs;
    • Yellow Ethernet link LED;
    • Green 100Mb LED.
  • Two control lines for attaching external green and red main status LEDs.
  • Power: 220mA @ 5V (100BaseT mode).
  • Dimensions (LxWxH): 30.1 x 18.1 x 5.5mm.
  • Dimensions with RJ203 (LxWxH): 31 x 20.0 x 15.5mm.
  • Operating temperature range: -20 ~ +70C.
  • Firmware is upgradeable through the serial port or network.
  • CE- and FCC-certified.

See Also:

  • RJ203 jack/magnetics front end

Files and Documentation:

SoI FirmwareEM_381D.BIN
DocumentationSerial-over-IP Solutions Manual
EM203 Hardware Manual
RJ203 Hardware Manual
CE Certificateds203a-ce.pdf (includes the EM203)
FCC Certificateds203a-fcc.pdf (includes the EM203)

Order the EM203

RJ203+EM203 module combination.
Not available in the U.S.