How to Find the Problem Node of the CAN Bus One Minute
The CAN-bus is a bus communication method that connects all nodes through CANH and CANL and realizes information channel sharing. While bringing convenience in wiring and cost savings, it also makes it more difficult for on-site troubleshooting. Because all the nodes are connected together, it is difficult to quickly determine the faulty node once maintenance or communication failure is required. As shown in Figure 1.
CANScope's "Signal Quality" Analysis Plug-in analyzes the waveforms sent from each CAN node automatically to its minimum voltage amplitude, maximum voltage amplitude, signal amplitude, waveform rising edge time, waveform falling edge time, signal time Comprehensive "score", and then through the histogram to visually show the signal quality of each CAN frame ID. Users do not need to know in depth the CAN bus protocol, eye diagram, slope, amplitude, ringing, ground bombs and other expertise. Just use CANScope to collect a period of time, and click the mouse to automate the analysis. as shown in picture 2. The parameters evaluated for six measurements.
The right side of the signal quality evaluation graph is the node with the best signal quality that emits 0x263 frame ID, and its worst quality also reaches 70 points. As shown in Figure 4,
Figure 4 CANScope signal quality analysis diagram (the best quality on the right)
The 0x308 waveform was viewed through the CANScope's waveform filter and it was found that there was a significant reflection of the "ground bounce" phenomenon and that the effective amplitude was relatively small. As shown in Figure 5.
Figure 1 CAN network connection
CANScope Analyzer Guangzhou Zhiyuan Electronics Co., Ltd. developed a comprehensive professional tool for CAN bus development and testing. It integrates mass storage oscilloscopes, network analyzers, bit error rate analyzers, protocol analyzers, and reliability test tools into one. , and organic integration and correlation of various instruments; redefining the CAN bus development test method, can carry out multi-angle comprehensive evaluation of CAN network communication correctness, reliability, and rationality; help users quickly locate the fault node, solve The various problems of CAN bus application are the ultimate tools for CAN bus development and testing. CANScope's "Signal Quality" Analysis Plug-in analyzes the waveforms sent from each CAN node automatically to its minimum voltage amplitude, maximum voltage amplitude, signal amplitude, waveform rising edge time, waveform falling edge time, signal time Comprehensive "score", and then through the histogram to visually show the signal quality of each CAN frame ID. Users do not need to know in depth the CAN bus protocol, eye diagram, slope, amplitude, ringing, ground bombs and other expertise. Just use CANScope to collect a period of time, and click the mouse to automate the analysis. as shown in picture 2. The parameters evaluated for six measurements.
Figure 2 CANScope signal quality analysis parameters
As shown in Figure 3. For the actual test results of a CAN bus on a subway vehicle, the signal quality is sorted in ascending order, and the node with a frame ID of 0x308 can be seen. The average signal quality is only 47 points, and the worst value is even 34 points. Figure 3 CANScope signal quality analysis diagram (the left is the worst quality)
The right side of the signal quality evaluation graph is the node with the best signal quality that emits 0x263 frame ID, and its worst quality also reaches 70 points. As shown in Figure 4,
Figure 4 CANScope signal quality analysis diagram (the best quality on the right)
Figure 5 Waveform with the worst signal quality
The waveform with the best signal quality of 0x263 is shown in Figure 6. There is no obvious reflection and the waveform is very neat. Therefore, the node that issues 0x308 needs to be removed for separate analysis.
Figure 6 The best signal quality
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