Communication system

Abstract

This system provides a communication system that can determine the timing of non-communication without monitoring the signal line level, and can perform highly accurate initialization of the communication function. [Solution] The communication system performs serial data communication between multiple electronic control units. A first communication unit 13 in electronic control unit 11 transmits a data signal SD to a second communication unit 14 in electronic control unit 12 in synchronization with a clock signal CLK1. The second communication unit includes an uncommunicated counter 18 that counts the time when no data signal is received from the first communication unit, and a holding unit 19 that holds abnormal information about the data signal. The second communication unit then performs a periodic task that monitors the uncommunicated counter and the holding unit at a frequency shorter than the communication cycle. If the uncommunicated counter is above a predetermined threshold and abnormal information is held in the holding unit, the second communication unit is restarted to initialize the communication function.

Claims

1. A communication system configured to perform serial data communication with a defined communication cycle between a plurality of electronic control units, each having a communication unit, wherein a first communication unit among the plurality of electronic control units transmits a data signal synchronized with a synchronization signal to a second communication unit among the plurality of electronic control units, The second communication unit includes a non-communication counter that counts the time during which the data signal was not received from the first communication unit, regardless of whether the synchronization signal has been received from the first communication unit, based on the synchronization signal of the second communication unit. The system includes a holding unit that holds abnormal information in the event of an abnormality occurring in the aforementioned data signal. The second communication unit performs a periodic task that monitors the uncommunicated counter and the holding unit at a frequency shorter than the communication cycle. A communication system that, when the aforementioned periodic task is executed, restarts the second communication unit to initialize the communication function if the uncommunicated counter is above a predetermined threshold and abnormal information is held in the holding unit.

2. The communication from the first communication unit to the second communication unit involves transmitting a communication frame that can be communicated within a specified time shorter than the communication cycle. The communication system according to claim 1.

3. The communication frame includes a data body and first verification data which is a calculation result obtained by the first communication unit from the value of the data body and is transmitted after the data body. The second communication unit calculates second matching data from the value of the data body of the received communication frame and compares it with the first matching data. The holding unit retains abnormal information if the matching fails multiple times. The communication system according to claim 2.

4. The communication frame includes a data body and a first identification value which is predetermined data transmitted before the data body. The second communication unit pre-stores a second identification value identical to the first identification value, and each time it receives a communication frame, it compares the first identification value with the second identification value. The holding unit retains abnormal information if the matching fails multiple times. The communication system according to claim 2 or 3.

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