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