APRILIA SHIVER 900 Service Station Manual page 192

Electrical system
of the electric system and consequently its total mass. With this communication line, it was possible to
avoid useless duplications of various sensors on the motorcycle, since the signals coming from them
are divided among the three electronic processing units (instrument panel, control unit and ABS).
•
Cable number reduction: The CAN line travels through a twisted cable to several nodes.
•
These nodes can also isolate the errors without causing a system breakdown (FaultsCon-
fination).
•
Immunity to interference: the signal travels through two cables and the signal reading is
differential (voltage difference between the two signals on both cables). If the two signals
are disturbed by an external factor, their difference remains unaltered.
•
Communication speed: The messages travel at a bit rate of approximately 500 kbps (de-
pending on the sent data package, the information may arrive at the nodes in a time carrying
from 4 ms to 100 ms).
CAN PROTOCOL (CONT. NETWORK AREA)
The communication protocol is CSMA/CD (Carrier Sense Multiple Access w/ Collision Detection).
In order to transmit, every nod must first check that the BUS (the connection among all devices) is free
before attempting to send a message with BUS (Carrier Sense).
If during this period there is no activity on BUS, every nod has the same chance to send a message
(Multiple Access). If two nodes start transmitting simultaneously, the nodes recognise the "colli-
sion" (Collision Detection) and initiate an exchange action based on message priority (messages remain
unaltered during exchange and there is no delay for high priority messages).
CAN protocol is based on messages and not on addresses. The message itself is divided into several
parts (frames), each of which has a meaning: message priority, data contained, error detection, recep-
tion confirmation, etc.
Every network nod receives all the messages sent through the BUS (with reception confirmation or error
messages) and each nod decides if the message is to be processed or rejected. Besides, every nod
can request information from the other nodes (RTR = Remote Transmit Request).
Level in electrical circuit diagram:
CAN Line
Electrical specifications:
•
between PIN 66 and 80 of the control unit: approx. 120 Ohm
•
between PIN 32 and 33 of the instrument panel: approx. 120 Ohm
Pin out:
•
Line L: cable X1 between ABS control unit PIN 66, instrument panel PIN 32 and ABS mod-
ulator PIN 6.
•
Line H: cable X2 between Marelli control unit PIN 80, instrument panel PIN 33 and ABS
modulator PIN 5.
CAUTION
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SHIVER 900