A bus device (10) the communicates with other bus devices (12, 13) on a communication channel (14) that includes a plurality of duplicated information buses (16, 17) selectively assumes bus-selection states in which it uses information from one or the other of the buses (16, 17). It also monitors the buses (16, 17) for errors in the information that the buses (16, 17) carry, and it broadcasts an error signal over other lines (18) of the communications channel (14) in response to detection of such an error, but only if an error occurs in information on the bus that its current bus-selection state designates. On the other hand, when an error-broadcast signal indicating an error on either bus in the information transmitted by that device (10) appears on the bus, that bus device (10) retransmits the information, regardless of that device's current bus-selection state. Inconsistent operation phasing among bus devices that have assumed different bus-selection states is thereby avoided.