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  1. #13
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    Mar 2007
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    1984

    Re: home switch on stb4100

    That will indicate the stb4100 input terminal is connected to the +24V via a resistor and the LED inside the opti-isolator as in the last photo in post 2


    most of the missing 2V will be the forward volt drop across the LED


    That means you can connect the proximity sensor directly to the stb4100 input terminal

    when the proximity sensor switches on the NPN transistor will ground the stb4100 input terminal to the -24V supply
    and I would expect a current of about 10mA will flow out of the stb4100 input terminal and to ground via the proximity sensor

    you can check this by connecting a stb4100 input terminal to ground via a meter set to the 200mA range


    John

  2. #14
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    Dec 2017
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    26

    Re: home switch on stb4100

    so i was worried about burning up the board for no reason i can connect it to the breakout board directly without doing any harm and don't need to drop voltage any the board with handle the voltage ?

  3. #15
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    Mar 2007
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    1984

    Re: home switch on stb4100

    yes, this time

    with other breakout boards or motion controllers designed to work at 5V logic levels it could of been different


    without any detailed information thats why I wanted to know what the stb4100 input open circuit voltage was

    now we know both the stb4100 input circuit and the proximity sensor both work at 24V levels

    you can connect them together

    John

  4. #16
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    Dec 2017
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    26

    Re: home switch on stb4100

    thanks you john for your understanding and patience i do appreciate the help and information

  5. #17
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    Mar 2007
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    1984

    Re: home switch on stb4100

    thank you
    as long as you have your machine working

    this is what you should have when the proximity sensor is connected to a stb4100 input

    Click image for larger version. 

Name:	limit switch input circuit.jpg 
Views:	0 
Size:	53.2 KB 
ID:	427040

    without your measurements I could not be sure there was not a voltage regulator reducing the +24V to a lower voltage to power the opto-isolators

    John
    Attached Thumbnails Attached Thumbnails limit switch input circuit.jpg  

  6. #18
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    Dec 2017
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    26

    Re: home switch on stb4100

    i have another question i hooked up the proximity sensor and its 20.6 and it drops down to .62 when its flagged but my question is on the breakout board it says there should be 0-10v at the dac and common part do you think it needs to be hooked up to the vfd to initiate the volt flow ? it also hook to the start and stop for the spindle?

  7. #19
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    Mar 2007
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    1984

    Re: home switch on stb4100

    Once mach3 is setup and sending a PWM signal to the DAC (digital to analogue converter)

    you should see the 0 to 10V control voltage between the DAC and COM terminals

    Attachment 427076

    I have not found a high resolution photos to reverse engineer the board to be sure the COM and -V terminals are isolated or connected together

    but from this photo you can see the +V connection goes via a diode that prevents damage if the 24V supply connections are reversed

    ( the diode can be seen in the bottom left hand corner )


    In general board follows the design pattern followed by many breakout boards

    Having what I expect to be a ULN2801 transistor array in a socket is a great advantage

    the IC can easily replaced if you short circuit the +24V to one of the 4 outputs


    A week ago I replaced a damaged FET in a AXBB motion controller

    see posts 39 & 40

    AXBB charge pump fault - Page 4

    John

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