MOTO GUZZI B043157 Service Station Manual page 163

Moto Guzzi California 1400
Rear speed sensor ground PIN 12
Front speed sensor ground PIN 13
Front speed sensor signal PIN 14
Vehicle identification (2) PIN 15
Serial K line for diagnostics PIN 16
Battery power PIN 18
Can line
Function
It allows communication between the Marelli injection ECU and the instrument panel.
Operation / operating principle
CAN SYSTEM ADVANTAGES
A CAN (controller Area network) line is a connection among the vehicle several electronic devices,
organised as a computer network (Internet). The CAN network has greatly simplified the electrical sys-
tem layout and consequently, its complexity. With this communication line, needless duplication of
several sensors present on the motorbike has been obviated. The sensor signals are shared by the two
electronic elaboration units (instrument panel and control unit).
•
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: messages travel at a speed of 250 kbps (data arrive at nodes every
20 ms, i.e. 50 times/second).
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.
Electrical system
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