Patent ID: 7522662

Claim:
An electronic device having a main-processing portion and a plurality of sub-processing portions, the electronic device comprising: a one-way data bus configured to connect the main-processing portion and the plurality of sub-processing portions in a loop for transmitting packet data; a plurality of signal lines configured to connect each of the plurality of sub-processing portions to the main-processing portion for transmitting a test signal; a generating unit configured to generate predetermined packet data that is transmitted and received by the main-processing portion via the one-way data bus in a case where an abnormality does not exist at any one of the plurality of sub-processing portions; a first transmitting unit configured to transmit the predetermined packet data from the main-processing portion to the plurality of sub-processing portions via the one-way data bus, wherein each of the plurality of sub-processing portions includes a unit configured to receive the predetermined packet data and to transmit the predetermined packet data; a determining unit configured to determine whether the abnormality exists at any one of the plurality of sub-processing portions or a part of the one-way data bus in accordance with whether the main-processing portion normally receives the predetermined packet data transmitted from the main-processing portion to the plurality of sub-processing portions via the one-way data bus; an abnormal portion specifying unit configured to specify the sub-processing portion or the part of the one-way data bus in which the abnormality exists by using the plurality of signal lines in case that the determining unit determines that the abnormality exists; and a second transmitting unit configured to transmit the test signal from the main-processing portion to one of the plurality of sub-processing portions via one of the plurality of signal lines, wherein each of the plurality of sub-processing portions creates a test packet including identification information for identifying the sub-processing portion and transfers the test packet to the main-processing portion via the one-way data bus in case that the sub-processing portion receives the test signal transmitted by the second transmitting unit, and wherein the abnormal portion specifying unit specifies the sub-processing portion or the part of the one-way data bus in which the abnormality exists based on whether the test packet including the identification information transferred from the sub-processing portion via the one-way data bus is normally received by the main-processing portion.