11 System bus "CAN on board"
11.10 Monitoring
748
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
11.10 Monitoring
11.10.1 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:
Tip!
The errors mentioned before indicate that a physical error has occurred in the bus system.
Possible causes are:
• Several nodes with identical node address
• Wrong baud rate of one or several nodes
•Too high cable length
• Too many or no terminating resistors
• Too high bus load/too many data telegrams
(e.g. since a node permanently transmits event-controlled due to data changes of an
analog signal/actual value.)
• EMC interferences on the system bus
(e.g. since the CAN bus cable next to the motor cable is unshielded.)
C00364
displays whether such an error is active.
Error Description
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 telegram, 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
bus controller, the bus controller will send an error flag after the ACK delimiter and
the previously transmitted telegram will be annulled.
Acknowledgement error If the sent ACK slot recessively sent by the transmitting node is not dominantly
overwritten by a receiver, 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.
To Next Page
Loading...
Need help?
General
