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Controller Disconnecting with Flood Activation

Discussion in 'Control Software' started by Kevon Ritter, Oct 6, 2017.

  1. Kevon Ritter

    Kevon Ritter Veteran

    Apr 30, 2015
    Likes Received:
    Phoenix CNC Controller GRBL 1.1e
    GRBL Panel

    I have the "Coolant" and its associated ground going through a JQC-3F(T73) relay. The relay triggers a small water pump which is what sprays the coolant onto the end mill.

    When the controller is only being powered by my PC, everything seems to work fine. I say "seems" only because I can not trigger the coolant port without main power.

    When the controller is only being powered by both my PC and it's 24V power supply, activating "M8/M9" (coolant on) causes the controller to quickly disconnect and reconnect. This is the equivalent to physically disconnecting the controller form my PC. Once that happens, GRBL Panel freezes, which is to be expected. During the disconnect/reconnect jump, GRBL Panel does not change it's connection status. The "digital" status remains connected. In order to regain control, I must digitally disconnect and reconnect. The following initialization is a bit weird. I have not been able to confirm exactly what happens after as it initializes a little differently each time.

    The coolant signal is 12V.

    One thing I thought about was resistant...or lack of. The picture below is directly from the creater of the board. Would adding a resistor help? If so, any recommended value?


    [​IMG] [​IMG]
  2. phil from seattle

    phil from seattle Journeyman

    Mar 17, 2017
    Likes Received:
    The relay coils are driven off of 12 or 24VDC. If you do not connect 12/24VDC, the problem doesn't happen? I think that is what you said. If true, then it is the relay on the controller board generating some sort of noise that is feeding back into the microprocessor circuit and resetting it. You could try isolating the relay from the board to see if it's the magnetic coil that's causing the problem. It appears that the board's 5V comes from USB so there should be isolation of the microprocessor's +5V rail from the 12/24VDC of the relays but there could be some sort of magnetic pickup from the relay if the 5V rail passes near it.

    One thing to check is to give the relay power but not connect the pump. Does the same problem happen or not?

    Also, make sure the USB cable doesn't go anywhere near your pump. I'd get a USB cable that also has at least a ferrite choke on it near the controller board. Even better, a shielded cable.

    [edit] to you question about a resistor. I don't understand where you would put it.

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