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Hi, guys. I have a question regarding CAN error counter. CAN specifications 2.0 says for the error active flag: The ACTIVE ERROR FLAG consists of six consecutive 'dominant' bits. An ’error active’ station detecting an error condition
signals this by transmission of an ACTIVE ERROR FLAG. The ERROR FLAG’s
form violates the law of bit stuffing (see CODING) applied to all fields from START OF FRAME to CRC DELIMITER or
destroys the fixed form ACK FIELD or END OF FRAME field. As a consequence, all
other stations detect an error condition and on their part start transmission
of an ERROR FLAG. So the sequence of ’dominant’ bits which actually can
be monitored on the bus results from a superposition of different ERROR FLAGs
transmitted by individual stations. The total length of this sequence varies between a minimum of
six and a maximum of twelve bits. Further it says for error delimiter: The ERROR DELIMITER consists of eight 'recessive' bits. After transmission of an ERROR FLAG each station sends 'recessive' bits
and monitors the bus until it detects a 'recessive' bit. Afterwards it
starts transmitting seven more 'recessive' bits. Now my question is regarding receive error counters. It says in the
spec: When a RECEIVER detects a 'dominant' bit as the first bit after sending
an ERROR FLAG the RECEIVE ERROR COUNT will be increased by 8. What is now "the first bit after sending an ERROR FLAG" ? Is it the 7th bit? The spec says that the error flag can be 6-12 bit
long. Is it the 13th bit? or 1st bit after the error delimiter? Thanks for the help. Best regards, Igor |