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Grundlagen FlexRay BasicsV 1.1 15
• normal active – This is the main operating state of the Communication Controller, in
which communication with the bus is possible
• normal passive – In case of specific errors, the node autonomously switches to this
state or the halt state. The node is only allowed to listen to the bus, but is prohibited
from transmitting data. If the AUTOSAR specification is used, this state isn’t used for
security reasons, since the microcontroller isn’t able to control the transition to the
state.
• halt – All processes in the Communication Controllers are stopped. This state is
reached, if an internal error of the Communication Controller occurs. It can only be
left via the default config state.
For detailed information, consult the FlexRay Communication System Protocol Specification
[FRPS05].
Figure 2.4 Structure of a FlexRay Active Star node [VeSc11]
In between Branches of a FlexRay network, an Active Star (AS) can be used. It consists only
of Bus Drivers, as shown in Figure 2.4.
2.3 Termination of nodes
To achieve a better signal quality on the bus and to prevent reflections on the end of the
cables, the cables get terminated at the ends. The most simple way to do that is shown in
Figure 2.5. It uses a resistor R T = 80...110Ω (110Ω typical) between Bus Plus (BP) and Bus
Minus (BM).
Bäurle 12.10.2012