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RS485 isolation and grounding

roman farber
Prodigy 10 points

Hello, 

I design a system for the outdoors. the system is a host to 1 - 2 external sensors connected via RS485 bus and also supplies the power to the sensors. the system can be powered by battery or ac (using ac/dc converter)

most guides advice not to use direct ground connections to avoid "ground loop" , in my system i have a direct ground connection since the system provides un-isolated 5V to the sensor

Please advice on how correctly use grounding and isolation if needed.   

  • 0
    TI__Guru 62920 points

    Hi Roman,

    It sounds like the sensors have a single ground connection via their interface to the master device and that they don't have an additional connection to ground. Is that correct? If so, then you wouldn't have a ground loop to worry about.  That would only happen if both sides had their own ground connection and then also connected grounds through the interface cabling.

    Regards,

    Max