28. March 2016 01:35 by Christian in
CAN Bus Off is an error state of the CAN controller and it can be set only by the Transmitter Node when Transmit Error Counter is above 255. Such critical error is usually the result of a critical hardware issue (e.g. high level of electromagnetic field, bus wiring short-circuit, defective transceiver).
Methods to self-recover from a Node CAN Bus Off state:
1) Automatically after the CAN controller generates an interrupt.
2) Manually upon User request (ISO11898-1 §6.15).
In both the above instances the bus turns back on after 128 occurrences of 11 consecutive Recessive Bits (BOSCH CAN 2.0B §8.12).
Auto-Bus-ON is not required by ISO 11989, therefore the CAN controller makers let the application to decide on its implementation. The automotive industry does not encourage the auto-bus-on feature.
If application's driver reports repeatedly the CAN Bus Off state the application should stop using the CAN.
Christian Rosu