Civil Engineering Reference
In-Depth Information
ers may switch off the “wrong” line resulting in stable subnets which can no longer
communicate with the “other” nodes.
6.2.5.7
Loss of Power/Ground
When a node has a disconnected Power or Ground line, it is not allowed to disturb
the communication of other nodes, e.g. by corrupted frame transmission caused by
backward-supplying from the bus lines.
6.2.5.8
Signal Propagation Delays
In a dedicated network the transmission time of signals will be measured. The “digi-
tal signal” will be applied to the transmit-pin (TxD) of the transceiver; there it will
be transformed into the “physical” bus signal. Afterwards, it can be received by
the other nodes and also by the sending node. While receiving, the transceiver will
retransform it to a “digital” signal and puts it out at the receive-pin (RxD). The al-
lowed delays between TxD of the sending node and RxD of the sending and another
receiving node are limited. Also the delays under ground shift and bus failure condi-
tions will be evaluated.
6.2.5.9
Verification of the Functionality of Further Essential Mechanisms
For the working of the correct state changes required by
fault tolerance
, some spe-
cial implementations are essential. So, e.g. the transceiver has to distinguish be-
tween “hard” and “weak” short circuits at the bus line because the differing bus
levels in Low-Power mode “behave” like weak shorts.
6.2.5.10
Test Cases of CAN High-Speed Transceiver Tests
The CAN High-Speed Transceiver tests are based on the following specifications:
• Transceiver specification:
− ISO 11898-2:2003 Road vehicles—Controller area network
(CAN)—Part 2:
High-speed medium access unit
− ISO 11898-5:2007 Road vehicles—Controller area network
(CAN)—Part 5:
High-speed medium access unit with low-power mode
• Test specification:
− CAN High Speed Transceiver Conformance Test, Test Specification V1.0
Due to the fact that the CAN High-Speed transceiver owns no “active fault toler-
ance” (auto-switching into one or two line mode, depending on failure occurrence/
recovery), at that test only “hard” failures will be applied. At some failures, the
