User guide

9 System bus "CAN on board"
9.8 Monitoring
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Lenze · 8400 BaseLine C · Reference manual · DMS 1.6 EN · 01/2014 · TD05
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9.8 Monitoring
9.8.1 Integrated error detection
If a node detects an error, it rejects the CAN telegram bits received so far and transmits an error flag.
The error flag consists of 6 consecutive bits with the same logic value.
The following errors are detected:
Bit error
The sending node follows the transmission on the bus and interrupts the transmission if it receives
a different logic value than the value transmitted. With the next bit, the sending node starts the
transmission of an error flag.
In the arbitration phase, the transmitter only detects a bit error if a dominantly sent bit is received
as recessive bit. In the ACK slot as well, the dominant overwriting of a recessive bit is not indicated
as a bit error.
Stuff-bit error
If more than 5 consecutive bits have the same logic value before the ACK delimiter in the CAN tele-
gram, the previously transmitted telegram will be rejected and an error flag will be sent with the
next bit.
CRC error
If the received CRC checksum does not correspond to the checksum calculated in the CAN chip, the
CAN controller will send an error flag after the ACK delimiter and the previously transmitted tele-
gram will be annulled.
Acknowledgement error
If the sent ACK slot recessively sent by the transmitting node is not dominantly overwritten by a re-
ceiver, the transmitting node will cancel the transmission. The transmitting node will annul the
transmitted telegram and will send an error flags with the next bit.
Format error
If a dominant bit is detected in the CRC delimiter, in the ACK delimiter or in the first 6 bits of the EOF
field, the received telegram will be rejected and an error flag will be sent with the next bit.