User Manual

©
Scania CV AB 2013, Sweden
CAN interface for bodywork
Requirements for CAN communication with the vehicle
11:90-01 Issue 1 en-GB 138 (139)
Fault validation of communication (Time-Out)
Avoid CAN communication when the starter key is in the lock or radio positions.
Also avoid CAN communication when starting up the control units connected to the
external CAN bus.
During normal operation, when the starter key is in the drive position, a message
should not be validated as missed (time-out) until at least 5 times the message period
time. A longer fault validation time is permitted.
During the engine start, when the starter motor is turning, the supply voltage can be
extremely low. Because of this, communication from the bodywork control unit can-
not be guaranteed during this period. For this reason, no fault codes related to CAN
communication with the bodywork control unit are set when the system voltage is
under 18 V.
When the starter key is turned to the drive position, the bodywork control unit starts
sending messages within 1,000 ms. A message sent from the bodywork control unit
cannot be considered missed until after 1,000 ms + 5 x the message period time, e.g.
if a message has a period of 100 ms it cannot be considered missed until after 1,000
+ 5 x 100 = 1,500 ms. Longer fault validation times are permitted.
When the starter key is turned to the radio or locked positions, the CAN messages
cannot expect acknowledgement. No communication from the bodywork control
unit can be expected.