We have to use the recommended mounting plate (TM7ACMP), it connects via both screws to the internal functional EARTH potential, that is used for diverting any interference voltage.
There is no connection of internal ground (electronic ground e. g. CAN_GND) to EARTH (module backplane or DIN rail).
CAN_SHLD (shielding) is connected to EARTH (module backplane).
CAN_GND (common internal potential of CAN circuit) is connected to EARTH only by a capacitor and a varistor for EMI reasons.
CAN_GND of master has to be connected to CAN_GND of slave. Will be done by appropriate cable. As well as shieldings will be connected.
