Abstract: A first data selection circuit selects a data signal among a plurality of data signals from a plurality of circuits, a first direction selection circuit selects a direction control signal of the same circuit among a plurality of direction control signals from these circuits. A data holding circuit and a direction holding circuit respectively hold the selected data signal and direction control signal. A second data selection circuit selects a data signal from the first data selection circuit or the data holding circuit. A second direction selection circuit selects the direction control signal from the first direction selection circuit or the direction holding circuit. An output circuit outputs, to a common input/output terminal, the data signal from the second data selection circuit in accordance with the direction control signal from the second direction selection circuit.

Abstract: In a communication system for transmitting/receiving redundant data between a first communication device and a second communication device, using first and second lines, the first communication device transmits first transmitting data to the first line, and also delays the first transmitting data by a prescribed time and transmits the delayed transmitting data to the second line as second transmitting data. The second communication device delays first receiving data inputted from the first line by the prescribed time and generates the delayed receiving data, and selects one of the second receiving data inputted from the second line and the delayed receiving data.

Abstract: A first data selection circuit selects a data signal among a plurality of data signals from a plurality of circuits, a first direction selection circuit selects a direction control signal of the same circuit among a plurality of direction control signals from these circuits. A data holding circuit and a direction holding circuit respectively hold the selected data signal and direction control signal. A second data selection circuit selects a data signal from the first data selection circuit or the data holding circuit. A second direction selection circuit selects the direction control signal from the first direction selection circuit or the direction holding circuit. An output circuit outputs, to a common input/output terminal, the data signal from the second data selection circuit in accordance with the direction control signal from the second direction selection circuit.