I am not sure, how to correctly connect a motor drive to reduce noise as good as possible. The drive runs on 48VDC and the power supply is galvanic isolated, so that GND and Earth are not shorted together. The power supply chassis is on Earth. The motor drive is a PCB without a Earth connector, only Ground points are available.
Everything is in an enclosure, which is pulled to Earth. The motor is also attached to the Earth potential. With this configuration the system works descent so far, but at high motor current, the encoder give more CRC errors, so there might be an EMC problem that should be fixed. The encoder cable itself is shielded with potential to Ground. The motor cable has no shielding, but I will replace the cable with a shielded one and I'm unsure, where I should connect the shield.
Normally, the Motor shield is connected to Earth, but in the end, the distrubances should be flow back into the distrubing source, as low impedant as possible. Since the disturbances need to come from the galvanic isolated motor drive, I think the shield should go to Ground? And if so, I'm not sure if Ground should also connect to Earth, since the motor chassis is already on Earth?