Abstract: A coupling controller that performs coupling control of a device with a bus includes a decision circuit configured to decide whether a voltage level of a signal inputted from each of a plurality of signal lines included in the bus is lower than a given threshold value, and a switching controller configured to perform switching control for a switching unit, which is interposed between the bus and the device and switches coupling between each of the plurality of signal lines and the device, such that the signal line with regard to which it is decided by the decision circuit that the voltage level of the signal is lower than the given threshold value is coupled with the device.

Abstract: There is provided a relay apparatus configured to relay data transmitted on a first bus coupled to a bus controller and a second bus coupled to a device, the relay apparatus includes: a memory; and a processor coupled to the memory and the processor configured to: control a switch to couple or separate the first bus and the second bus, and transmit first data for indicating a bus access start to the second bus before coupling the first bus and the second bus.

Abstract: A coupling controller that performs coupling control of a device with a bus includes a decision circuit configured to decide whether a voltage level of a signal inputted from each of a plurality of signal lines included in the bus is lower than a given threshold value, and a switching controller configured to perform switching control for a switching unit, which is interposed between the bus and the device and switches coupling between each of the plurality of signal lines and the device, such that the signal line with regard to which it is decided by the decision circuit that the voltage level of the signal is lower than the given threshold value is coupled with the device.