MD-21 DIN Rail 20mA Current Loop Converter
The MD-21 is used for applications where equipment requires a 20 mA current loop interface: for example with cash register systems and some PLC-systems. The MD-21 converts 20 mA current loop to RS-232/V.24. The units can be used in point to point applications and also for ring connection with a maximum of 6 nodes. The converter can be switched to active as a current source or to passive, depending upon the configuration of the connected equipment. The maximum transmission rate of the MD-21 is 19 200 bit/s. The MD-21 is designed to fit on a standard 35 mm top hat DIN-rail.


  • Conversion between 20mA and RS-232/V.24 interface
  • Protects connected units from lightning/transients
  • Total galvanic isolation
  • Data transparent
  • Use to connect equipment on different earth potentials
  • Guarantees reliable long-distance communication

MD-21 Diagram