| 摘要 |
PROBLEM TO BE SOLVED: To more precisely locate a failure point of causing a communication error and possibly avoid sending unwanted test data during a communication test. SOLUTION: ECU 11a, 11b, 11n constitute a vehicular LAN with a transmission line 15. A test control circuit 39 normally outputs a control signal Sa at a level L. A transmitter circuit 37 sends its output signal to the transmission line 15 through a buffer circuit 40 and a transceiver 13, and a receiver circuit 38 receives the signal once returned to a microcomputer 12. If a communication error occurs, the test control circuit 39 outputs a control signal Sa at a level H and a transmitted signal is directly returned to the receiver circuit 38 through a received signal switching circuit 41 while the buffer circuit 40 blocks the transmitted signal from being sent out to the transmission line 15. COPYRIGHT: (C)2003,JPO
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