| 摘要 |
A communications device for a control device is provided which includes a signal line communicating with the control device, and a transmitter that transmits a pulse signal including digital information to the control device through the signal line. The transmitter varies a duty ratio of the pulse signal so that the duty ratio corresponds to the logical value 1/0 of the digital information. The control device reads a binary signal from the signal line at a predetermined frequency based on a first processing program, and processes the binary signal according to the first processing program. The control device detects passage of a leading edge of the pulse signal from a change in the received binary signal, and reproduces the digital information based on the binary signal read at a time when a first predetermined time elapses after the passage of the leading edge of the pulse signal is detected. The first predetermined time is set to be intermediate between the varied duty ratios. The control device detects an abnormality in the communication by detecting that at least one of the rise and fall of the binary signal disappears.
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