Civil Engineering Reference
In-Depth Information
Fig. 3.14
System with two redundant CAN nodes connected with two transceivers (
left
) as well
as system with only one transceiver (
right
)
On MultiCAN, a feature has been introduced to measure the actual transceiver
delay and to check if the bus termination is properly done. By being able to measure
the time between a falling edge being transmitted by the CAN node, until this fall-
ing edge is received, the actual transceiver delay can be measured.
3.4.3.2
MultiCAN Supports CAN-Debugging
For safety critical applications, MultiCAN is giving some possibilities to support
fault tolerant implementations. An example is shown within this section.
If two CAN nodes are connected to the very same bus, we do have the possibility
as shown in Fig.
3.14
.
Two CAN nodes, via two CAN transceivers, are connected to the very same
bus (Fig.
3.14
, left). The advantage is at the same time the disadvantage of the
concept. Two transceivers are used, which means higher cost. As one mod-
ule shall only listen to bus, the transmit line does not need to be connected. The
comparison between the messages is done via software. Due to the fact that two
transceivers are used, also transceiver errors can be found, as two transceivers
are used.
In the right part of Fig.
3.14
, a similar approach is shown, having only one CAN
transceiver. The advantage is on the cost side, having only one transceiver. The dis-
advantage remains that here transceiver errors cannot be found.
In case of having two separate modules, small disturbances can be seen on both
nodes at the very same time; therefore, such an issue remains undetected. The Mul-
tiCAN module helps to overcome the absolute synchronism.
