A fieldbus system normally provides very efficient and fast communication when you have all the connected equipment in a single building of limited size. As soon as your system is spread over a wide area and maybe also in a harsh environment you need to use communication equipment for extension and protection. A 4-wire modem with different serial interfaces (RS-232/V.24 and RS-422/485) and a balanced current loop interface makes it possible to extend the lines and build very complex bus-systems. The LD-01/02 enables 9 600 bit/s at distances of up to 2.5 km and the possibility to connect either RS-232/V.24 or RS-422/485 interfaces to the network. The modem/line sharing unit gives your system complete galvanic isolation and ensures that connected equipment will not be disrupted.