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(4) Error statuses
(a) Types of error statuses
The three types of error statuses are listed below.
Error active
Error passive
Bus off
• Error status is controlled by the transmit error counter and receive error counter (see 11.10 (23) CAN1
error count register (C1ERC)).
• The various error statuses are categorized according to their error counter values.
• The error flags used to output error statuses differ between transmit and receive operations.
• When the error counter value reaches 96 or more, the bus status must be tested since the bus may
become seriously damaged.
• During startup, if only one node is active, the error frame and data are repeatedly resent because no
ACK is returned even data has been transmitted.
In such cases, bus off mode cannot be set. Even if the node that is sending the transmit message
repeatedly experiences an error status, bus off mode cannot be set.
Error Status Type
Error active
Error passive
Bus off
542
CHAPTER 11 FCAN CONTROLLER
Table 11-12. Types of Error Statuses
Operation
Error Counter Value
Transmit/
0 to 127
receive
Transmit
128 to 255
Receive
128 or more
Transmit
256 or more
User's Manual U14492EJ3V0UD
Type of Output Error Flag
Active error flag (6 consecutive "dominant
(D)" bits)
Passive error flag (6 consecutive "recessive
(R)" bits)
Transfer is not possible.
When a string of at least 11 consecutive
"recessive (R)" bits occurs 128 times, the
error counter is zero-cleared and the error
active status can be resumed.
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