CAN/TWAI bus arbitration lost

[cziter15]

Hello,

I am using a custom ESP32 board with a SN65HVD230 CAN/TWAI transceiver. The bus is terminated at both ends, and the module acts as unterminated stub, with cable length of around 30cm. The bus speed is 125kbps and I am sending around ten frames every 15 seconds. Most of these frames result in arbitration loss, but the message is eventually transmitted and the other side responds. Under normal operation, there is not so much traffic on the bus (around 50 messages per second).

After a few hours, the bus error count on my module suddenly changes from 0 to ~15 or so and few requests are marked as timed out (not receiving response). Then, everything returns to normal. However, after a few more hours, there is a bus off, and the code initiates bus recovery. This cycle repeats.

While the device functions properly from a functional perspective, I am concerned about the high rate of arbitration loss and bus errors. There is also another thing - ESP32 TWAI errata, which says that "some frames might be dropped", but it is very unclear.

My question therefore is - where can I look for the reason of a high rate of Arbitration Lost? Or is this completely normal?