12 788 445 3
Saab 9-3 M03-
Bus Communication
A number of sections in the car's electrical system
communicate using buses. There are three different
types of bus communication: P-bus (Powertain bus),
I-bus (Instrument bus) and O-bus (Optic bus). The
audio system, together with the navigation and tele-
phone system, communicate via the O-bus.
The O-bus is both an optic bus and a ring bus. Two
fibre-optic cables are connected to each control
module on the bus, one cable for receiving and one
for transmitting. Received messages are converted
by each control module from an optic signal to an
electric signal; signals are converted back into optic
signals when transmitted. Data transfer speed for
the O-bus is 25 MB/s.
AMP1 - amplifier located under the left-hand front seat
AMP2 - amplifier located near the REC
CDC - CD changer near the REC
DVD - DVD player near the REC
When fitting new equipment which is to be connect-
ed to the O-bus, it is important that the equipment is
connected on the correct side of the equipment
already present.
Important
It is very important that everything connected to the
O-bus is connected in a specific order (see illustra-
tion) and that the ring is closed at all times.
Connections made by means other than those
described in these installation instructions may
cause malfunctions in a number of other car sys-
tems.
F930A100
1
2
CDC
1
2
DVD
1
2
AMP2
1
2
1
2
AMP2
CDC
1
2
1
2
AMP2
DVD
1
2
1
2
DVD
CDC
1
2
1
2
1
2
AMP2
DVD
CDC
2 1
Important
Handle the fibre-optic cables with care or the sig-
nal may be distorted.
·
It is very important that the two leads in the
connector are not confused with one another.
·
Do not splice the cables.
·
Do not bend the cable in a radius smaller than
25 mm.
·
Do not expose the cable to temperatures
exceeding 85 °C.
·
Keep the cable ends free from dirt and grime.
·
Do not expose the cable to impact as this may
cause the transparent plastic to whiten, there-
by reducing the intensity of the light and caus-
ing possible communication interruptions.
·
The cable should not lie against any sharp edg-
es as this may cause increased signal reduction.
