S12ZVC CAN

[xiaohui200808]

Hello

        Now I am testing the CAN  PHYSICAL of S12ZVC .The dominant bit  voltage of CANH is 4.5V,sometimes 4.7V . when I connect CANH and CANL，MSCAN will enter Busoff ，when I unconnect CANH and CANL ，MSCAN will leave Busoff.  But when I connect CAN L and Ground .MSCAN never enter busoff ，when connect CAN H and Battery (12V), MSCAN never enter busoff. Is there any problems

[RadekS]

Hi Xiaohui,

The CAN bus used in automotive mainly for their robustness.

The CANH and CANL are differential signals. Therefore, when you make short between CANH and CANL line, you fully damage the bus communication. However, when you damage only one of CANH or CANL lines by short to power supply lines (or 12V), the PHYs still may reconstruct information from remaining CANH/CANL line and continue in operation.

I hope it helps you.

Have a great day,
Radek

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