No Ground PIN Available at D-Sub Connector of Vector BroadR-Reach (BR) Interfaces

There is a big difference concerning the galvanic isolation of CAN Interfaces and DC Isolation of BroadR-Reach Interfaces.

According to the Open Alliance TC1 100BASE-T system implementation specification in Chapter 7.2 Interface circuitry definition, a BR-Bus shall be DC isolated at the analog front end (i. e. between BR-Phy and D-Sub). Therefore there is no DC reference of the BR-Bus. Whereas a CAN bus is isolated on the digital side of the transceiver (i. e. before the transceiver) and the CAN-Signal refers to GND of the transceiver.

This is the reason why, the Vector Interfaces for BR have no Ground connected to the D-Sub. The Vector Interfaces for CAN bus have the supply ground of the transceiver connected to D-Sub pin 3.

Consequently, no Ground Shift Test is sensible for BroadR-Reach. Moreover, shifting any Ground to the D-Sub shield of Vector Interface might have fatal consequences for the Interface and the PC it is connected to. Because D-Sub shield is identical with System GND and USB GND.