Figure 5-6 Can Status Transition - Fujitsu FR Family FR60 Lite User Manual

Transition between the statuses is described below along the example shown in "Figure 5-6 CAN
status transition". The initial status of a node is error active. In this status, occurrence of errors
increases the TEC/REC counters.
If either of the TEC/REC counters comes to 127 or higher, the status of the node changes to error
passive. In this status, the node remains communicable and the values of the counters decrease
whenever a communication session is normally carried out.
When both the TEC/REC counters decrease to 127 or less, the status of the node returns to error
active.
If the TEC counter increases after the node comes to error passive and the count comes to 255 or
higher, the status of the node changes to bus off.
If the status of the node becomes bus off, the node cannot be restored to error active unless the
restoration condition that successive 11-bit recessive is received 128 times is satisfied.
Initial status
and
or
Error passive
Error active
Reception of successive
11-bit recessive 128 times

Figure 5-6 CAN status transition

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Bus off
TEC: Transmit error counter
REC: Receive error counter