Shared ground connection with fan, Z-probe and E0-probe?

  • Using the search tool I didn't find an answer to my question below.

    To save some wiring I want these parts to share their ground connection:

    • Always On fan
    • Z probe board
    • E0 temperature probe

    Could there be a problem?

  • administrators

    Do not share the always-on fan ground connection with either of the others. It may induce noise on the other signals, and if the ground connection breaks then you end up feeding 12/24V through the fan to the thermistor input and the Z probe input (although both are protected from over-voltage on the Duet WiFi).

    You could share the thermistor and IR sensor grounds, although this may lead to a slight loss of temperature reading accuracy and additional noise in the temperature reading at high temperatures. Use the IR sensor ground connection on the Duet (not the thermistor ground) to avoid blowing the VSSA fuse.

  • Thanks for making this clear.
    So I won't use shared ground connections.
    It's just not worth it.

  • administrators

    Yes, to add for anyone else reading this thread the temperature ground is a seperate ground on the DuetWifi to reduce interference and it is protected by a small SMT fuse. Care should be taken with the ground on any thermistor circuits.

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