Preventing errors and defects in the communication interface by a proper choice of an earthing concept.
The earthing and grounding concept of devices installed in a system can strongly influence the risk of compensating GND currents through communication interface lines. Especially USB interfaces are sensitive for such stray electrical currents by the USB's GND. The USB port of the controller or even the PC's USB can be damaged by this.
Particularly high motor output currents of a controller and/or long supply voltage lines with a thin cross section can be critical concerning instable or different GND levels and stray electrical currents due to this. The resulting GND current can affect communication interfaces in a negative way or even destroy electronic components of the drive controller or the master.
Correct earthing, respectively selective galvanic isolation will solve the problem.
Please observe the following principles:
- Use accurately dimensioned cable cross-sections for the power supply to receive low-resistance connections.
- Make sure that the power supply, controller, and additional components are mounted and connected following the local and statutory requirements.
- Follow the recommendations for EMC-compliant installation.
The attached document "ENGLISH_mmc_Earth_GND-Concepts_V1-00en.pdf" holds different diagrams showing "NOT RECOMMENDED" and "RECOMMENDED" earthing concepts. Please take care that your earth and GND wiring corresponds to one of the "RECOMMENDED" earthing variants.
Please also take care of a using shielded cabels and attaching the shield to Earth in a proper way. More information about this is present by the "How to connect cable's shielding to Earth".
If there is a risk of different GND levels (due to different power supplies or batteries) within a system or some damage of USB ports has been observed in the past, it is recommended to use an USB isolator. The USB isolator ensures that there is no connection in between the controller's USB and the masters's USB, i.e. there can be no stray electrical current present by USB GND and there is no defect possible due to this anymore.
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