| 摘要 |
PROBLEM TO BE SOLVED: To make the reception side of two control means (microcomputers) for transmitting data through a serial data transmission means detect a data transmission stopping state and the abnormal state of a signal path such as disconnection of a wire on a transmission side as early as possible without increasing a new signal path and carry out corresponding control. SOLUTION: When a host microcomputer 10 is in the data transmission stopping state, a signal level at the signal line 31a of a serial data transmission means 30 is held at an L (low) level. When the signal line 31a is disconnected, the signal level is pulled up to an H (high) level and held. the signal level of the signal line 31a is detected by a voltage level switch 40. A sub microcomputer 20 discriminates a signal transmission state at the serial data transmission means 30 by distinguishing at least the data transmission stopping state from the abnormal state of the signal line 31a on the basis of data stored in a reception buffer and the detected signal level, and controls an apparatus on the basis of the result of discrimination. COPYRIGHT: (C)2007,JPO&INPIT
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