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RAD-Galaxy User’s Guide
8
© 2016 Intrepid Control Systems, Inc.
Version 1.2 - November 28, 2017
Odd Nodes to
Even Nodes
PC to
Odd Nodes
PC to
Even Nodes
AE
Node 4
AE
Node 12
PC
RAD-Galaxy
Tapped
from
Even
Nodes
Tapped
from
Odd
Nodes
Even Nodes
to Odd Nodes
...
...
...
AE
Node 1
AE
Node 3
AE
Node 11
AE
5
AE
7
AE
9
AE
8
AE
6
AE
10
Figure 5: Using the RAD-Galaxy as Both an Active Tap and Media Converter.
In this variation on the configuration
shown in Figure 3, we have removed AE Node 2. This leaves Node 1 as the only node on that pair, so it only talks to the PC,
effectively now operating as if connected through a media converter. Meanwhile Nodes 3+4, 5+8, 7+6, 9+10 and 11+12 remain
in pairs functioning in active tap mode.
Timestamping and Frame Wrapping
The RAD-Galaxy records the time that each message is received on any of its Automotive
Ethernet ports. This hardware-level timestamp is then transmitted in a special
wrapper frame
over its conventional Ethernet links, encapsulating the original message. The wrapper frame
contains its own Ethernet header and
Frame Check Sequence
(
FCS
) field, along with an extra
header containing information specific to the RAD-Galaxy.
Ethernet controllers normally discard any frames received for which an error has been
detected, and strip the FCS error-detection field even on valid frames. The RAD-Galaxy’s
special wrapping mechanism allows it to capture BroadR-Reach frames in their entirety,
including the FCS field, and ensures that error frames are preserved so they can be analyzed.
Conventional Vehicle Network Interfacing
In addition to its Automotive Ethernet capabilities, the RAD-Galaxy can act as an interface to
conventional vehicle networks. It includes hardware for 8 CAN channels, with CAN FD support,