The MD-12 is a short haul modem allowing RS-232 systems to be connected over long distance. The serial interface is a standard RS-232 interface with five control signals. The connection between the modems is a balanced current loop allowing distances up to 18 km. (11.18 mi).

Since the communication is totally transparent no communication settings are necessary. The RS-232 serial interface is connected through a standard 9 pole D-sub or alternately through a terminal block with screw connectors.

The MD-12 is designed for use in heavy duty industrial applications. The different power options, galvanic isolation, transient protection guarantees communication in the worst environments. The MD-12 has been tested to meet many EMC, isolation, vibration and shock standards, all to the highest levels suitable for heavy industrial environments.

The design of the short haul modem makes the MD-12 suitable for a variety of applications with various speed and data bit options. DIP switches are used for configuration options of the control signals. One control signal can be transmitted in both directions.