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  1. #11
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 4-5 years. Has a total post count of 303. Received thanks 35 times, giving thanks to others 10 times.
    Quote Originally Posted by cropwell View Post
    If you are using GRBL v0.9 then D11 should put out a 0-5v analogue signal
    https://github.com/grbl/grbl/wiki/Connecting-Grbl. I have the feeling that describing D11 output as PWM is in error.
    No. The MEGA328/2560 based arduinos do not have a DAC, or any other form of analogue output. They provide a number of PWM-enabled discrete outputs (those prefixed with a tilde on the board silk-screening) with the signal value switched between GND and VCC - which if used for e.g. LED drives allows a direct control over the LED luminance, similarly for a DC motor drive; but the output remains a digital PWM signal (they do, however, support multiple ADC inputs)
    Last edited by Doddy; 30-05-2018 at 06:39 PM.

  2. #12
    Quote Originally Posted by Doddy View Post
    No. The MEGA328/2560 based arduinos do not have a DAC, or any other form of analogue output. They provide a number of PWM-enabled discrete outputs (those prefixed with a tilde on the board silk-screening) with the signal value switched between GND and VCC - which if used for e.g. LED drives allows a direct control over the LED luminance, similarly for a DC motor drive; but the output remains a digital PWM signal (they do, however, support multiple ADC inputs)
    You are right Doddy, I have had a closer look at the AnalogueWrite function. The DAC converters in the arduino put out a variable duty cycle PWM 0-5v. I have a feeling that that is where the OP's problem lies. I fell into the trap of assuming that, when Arduino described the board as having DAC function they meant in in the true sense. Maybe a simple RC integrator would prove the root of the problem, but in the long term an OpAmp circuit would be better (to give a better 0-5v). I am surprised that the inverter does not have an integrator on the input VI.
    Last edited by cropwell; 30-05-2018 at 07:14 PM.
    Albert Einstein may have been a genius, but his brother Frank, was a monster

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  3. #13
    Quote Originally Posted by Doddy View Post

    Eh?, I'm a little confused - I'm assuming that you have an adequately earthed connection to the machine?, my next thoughts would be how the supply earth is exported to the garage - whether through a 3-core cable or a local earth rod... but you're clear that the trip also occurred in the house and that the RCD circuit is okay, so I won't pursue that.

    What do you mean by grounding the machine earth through an additional PSU - currently laptop power - I'm not aware of a laptop PSU that exports an earth - I'm guessing from the language that you've connected the negative supply to the machine earth??, if that's the case then that isn't earthing the machine and this could be a cause of your problem. Absolutely provide a low-impedance earth strap from the machine to the garage supply earth. Also - from your picture of the machine - make sure that all exposed metalwork has a reliable earthing.
    Well the machine and all the machines metal parts are earthed so the spindle, power supplies for the drivers etc all go to earth - being in the UK almost everything here is earthed. In my garage this comes through 3 core cable. The spindle has also been earthed by myself and this runs through the spindle cable.

    However the electronics box/machine case, ardunio, relay are not earthed... I can work out the machine case but I'm not sure how you earth a arduino board?

    Also the board I'm using is running grbl 1.1
    Last edited by Mr*Beaver; 30-05-2018 at 07:16 PM.

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