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 MA-29 is used for applications where equipment requires a 20 mA current loop interface: for example with cash register systems and some PLC-systems. The MA-29 converts 20 mA current loop to RS-232/V.24.

The MA-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 MA-21 converts20 mA current loop to RS-232/V.24.