The system DL232-MUX is a multiplexer for 4xRS232 signals, working bidirectionally via fiber optics. Thus, in addition to the RxD and TxD signals, hardware-handshake signals as RTS, CTS, DCD, DSR and DTR can be transferred, too.

RS232-multiplexers have a similar pin assignment as modems. Two multiplexers, connected by fiber optics, cross the wires and operate like a null modem cable.

Hence, connecting two data processing terminals (with PC pin assignment) requires two 1:1 cables to be able to link the terminals to the multiplexers. Terminals with a DCE- pin assignment have to be connected to the multiplexer via a null modem cable.

LEDs and potential-free contacts (optional) of a fault detector relay are able to signal defective states.