excom I/O System. PROFIBUS-DP fiber-optic coupler for zone 1. Ident. no.: 6890427. Device for data transmission between electrical and optical fieldbus circuits. Power supply of max. 31 nodes. OM1 (62.5/125) for transmitting data over distances up to 2500 m. OM2 (50/125) for transmitting data over distances up to 1500 m. Mounting in zone 1 possible. Note: Idle level corresponds to active light!