Models 5843 and 5844 offer single channel RS232 signal extension up to 5km over a single pair of multimode fibre optic cables. The units comprise conformally coated PCBs securely mounted in rugged housings. They are ideal for all applications where the 15m limitation of RS232 needs to be overcome or the noise immunity of fibre is essential. 5941 and 5942 versions offer unique functionality in addition to the general robustness of the series. D1 versions provide full hardware handshaking including RTS-CTS and DTR-DSR control. These hardened units are ideal for operation in truly industrial environments.