EM203 Ethernet Module

10/100BaseT Ethernet port

Four LEDs onboard

One CMOS serial port

Compact (30.1x18.1x12.5mm)

Mates with RJ203 jack/magnetics

  • About

  • Hardware

  • Functionality

The EM203 is a miniature serial-to-Ethernet module. In combination with the RJ203 jack/magnetics, the EM203 occupies only 31x19mm of board space. Alternatively, the EM203 can be used with any suitable magnetics and jack.

The EM203 is offered with Tibbo Device Server Toolkit software, which includes Virtual Serial Port Driver for Windows and Linux.

The module can be ordered standalone or in combination with the RJ203.

Not available in the U.S.


  • 10/100BaseT, auto-MDIX Ethernet port (no magnetics):
    • EM203: based on the DM9000B controller IC;
    • EM203A: based on the DM9000EP controller IC.
  • CMOS serial port (TX, RX, RTS, CTS, DTR, and DSR lines).
  • Four status LEDs onboard.
  • Two control lines for green and red status LEDs.
  • Can be used with RJ203 (EM203) and RJ203A (EM203A) modules.
  • Power: 220mA @ 5V.
  • Dimensions: 30.1x18.1x5.5mm.
  • Firmware is upgradeable through the serial port or network.

See also:
RJ203 Jack/Magnetics module

Serial-over-IP firmware:

  • Full- and half-duplex serial port modes.
  • Server, client, and server/client network ("routing") modes.
  • 8KB data buffers (one in each direction).
  • Configuration stored in the EEPROM.
  • Detailed status indication via onboard LEDs.
  • Setup through the serial port or network (UDP, Telnet).
  • Remote control of RTS, CTS, DTR, and DSR lines.
  • "On-the-fly" commands for immediate serial port configuration.
  • Serial-side "modem" commands for network connections control.
  • Direct control of ADSL modems.
  • Supports UDP, TCP, ARP, ICMP (ping), DHCP, PPPoE, LCP.
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This product is a member of the x20x family.