XC90 FWD L6-3.2L VIN 98 B6324S (2007)
and the driver information module (DIM) in the example above.
Introduction of logic functions does not increase the number of components or cables.
Easy to adapt the system to customer and market requirements.
The functions can be altered depending on the requirements/demands of the customer and market. An example of this could be fog tail lamps. Certain
markets use two fog tail lamps, others only use one on the driver's side. Previously it was required that different replacement parts were stored for
different markets. Now the same replacement part can be used for all markets, by changing the programming depending on the market.
A similar basic system can be used for a whole model programme.
Similar networks (hardware) can be used for a large number of different cars.
The only thing which differentiates the cars is:
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the components (control modules, sensors controlled components etc.) which are connected to the system
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Which components do what
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Which components/functions are standard/optional/accessories
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The configuration/programming of the system.
Construction of the Network
Construction of the network
General
The network is made up of a number of control modules (sometimes called nodes)which are connected to each other serially via two communication
cables. Each control module is supplied with power and grounded individually and receives messages/commands via the two communication cables. In
both networks (high and low speed sides) the control modules are serially connected. In the event of an open-circuit those control modules beyond the
open-circuit will not be able to communicate with other parts of the network.
High and low speed sides on the network
The network consists of two parts: a high speed side (HS CAN) which transmits signals/messages between the central electronic module (CEM) and
control modules in the engine compartment (generally), and a low speed side (LS CAN) which transmits signals/messages between the central electronic
module (CEM) and control modules in the passenger compartment and luggage compartment.
The interface between the high and low speed sides is supplied by the central electronic module (CEM) which speeds up or slows down the
communication between the two network sides.
Transfer speeds
The Volvo Controller area network (CAN) has two transfer speeds.
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HS CAN (high speed) has a transfer rate of 500 kbit/s.
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LS CAN (low speed) has a transfer rate of 125 kbit/s.
1 kbit/s = 1024 bits per second (1 byte = 8 bits).
For serial communication (Volcano Lite) between a control module and a slave control module the transfer rate is 10.4 kbit/s.
There is another serial standard known as IN. This is an international standard which is becoming more commonly used. Its function is almost identical
to that of Volcano Lite. The difference is in the communication method and rate. The transfer rate for LIN is 9.6 kbit/s.
Terminating resistor
To prevent electrical reflections and interference in the CAN network, there are terminating resistors which bridge CAN H and CAN L, one at each end
on both the high and low speed sides of the network. Each terminating resistor has a resistance of 120 ohms.
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For HS CAN (high speed), the terminating resistors are located in the brake control module (BCM) and the engine control module (ECM).
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For LS CAN (low speed), the terminating resistors are located in the upper electronic module (UEM) and the rear electronic module (REM).
Both the terminating resistors create a parallel circuit The following resistors can be measured under specified conditions:
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When the CAN network is entire, the resistance on the network is approx. 60 ohms.
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In the event of an open-circuit on the wires, the resistance on the network is approx. 120 ohms.
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In the event of a short-circuit between the communication wires, the resistance is approx. 0 ohms.
Error Management In the Controller Area Network (CAN)
Error management in the Controller area network (CAN)
General
The CAN network is monitored by the central electronic module (CEM). When the central electronic module (CEM) detects a fault in the CAN network,
