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Thread: Apex base module or Apex VDM ground question

  1. #1
    Regular Vistor
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    Apex base module or Apex VDM ground question

    Does anyone know if the grounds on the 0-10V ports are common across the two jacks?

    I want to do independent control of my Kessils and the Kessil cable uses a common ground for each jack. But that only gives me one light per jack. Since I don't want to control the color, I "should" be able to use one jack for color and one light intensity and then use the other jack to control two more intensity channels and then combine the color output back into them. This would let me control three Kessils independently for intensity with all three using the same color setting. That is IF the grounds on the two jacks are all connected.

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  2. #2
    Frequent Contributor zombie's Avatar
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    They are floating grounds not common, but become common when tied. With that said, the far easier was is to use 1/8" TRS splitters, which kessil sells and chain the lights together with those and 1/8" TRS to 1/8" TRS cables of your desired length between them. Doing it this way requires no DIY, is very clean, and only uses one jack.

    You might be an engineer if...You have no life and can prove it mathematically.

  3. #3
    Master Control Freak RussM's Avatar
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    Quote Originally Posted by zombie View Post
    They are floating grounds not common, but become common when tied. With that said, the far easier was is to use 1/8" TRRS splitters, which kessil sells and chain the lights together with those and 1/8" TRRS to 1/8" TRRS cables of your desired length between them. Doing it this way requires no DIY, is very clean, and only uses one jack.
    The ground pins (2 & 6) of both the V1/V2 & V3/V4 ports are all tied together internally in the Apex Classic base, the Apex 2016 base, and the VDM; they are not independent as you imply. This is something that can be easily inferred by someone of your background, since the Kessil cables (and also the VarioS & Icecap Gyre Interface cables have TRS (3-wire connectors). See the Kessil wiring diagram in the DIY area which shows that only 3 wires are needed for dual-channel control, which would not work if the ground pins of a Varspd port were not internally common.

    Kessil fixtures which support 0-10v control use TRS (standard 1/8" stereo headphone) connectors, not TRRS. Kessil's accessories page does not list a splitter. Got a link?
    Please do not send me PMs with technical questions or requesting assistance - use the forums for Apex help. PM me ONLY if the matter is of a private or personal nature. Thanks.

  4. #4
    Frequent Contributor zombie's Avatar
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    I assumed they were floating cause I used a multimeter across the ground pins a while back and got 0.5V that dropped to sero over the course of about a second. Could have just been noise, but that's why I assumed floating.

    The splitter was an oversight. I was thinking of a different light. You just need the unit link cables, which are the same as an aux cable you would use on a home stereo.

    You might be an engineer if...You have no life and can prove it mathematically.

  5. #5
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    Quote Originally Posted by zombie View Post
    They are floating grounds not common, but become common when tied. With that said, the far easier was is to use 1/8" TRS splitters, which kessil sells and chain the lights together with those and 1/8" TRS to 1/8" TRS cables of your desired length between them. Doing it this way requires no DIY, is very clean, and only uses one jack.
    Unfortunately that ties all of the lights together and will not allow for a nice sunrise/sunset effect as one side of the tank gets lit, then the center, then the other side.

    RussM's information appears to confirm what I suspected given the design of the breakout box and that V1/V2 were using a common ground ( and V3/V4 obviously ). I just wasn't sure if the grounds between the jacks would be tied together as well. It would seem odd that they wouldn't be but I never underestimate the ability of a designer to outclever themselves.

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    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by shoggoth43 View Post
    Unfortunately that ties all of the lights together and will not allow for a nice sunrise/sunset effect as one side of the tank gets lit, then the center, then the other side.

    RussM's information appears to confirm what I suspected given the design of the breakout box and that V1/V2 were using a common ground ( and V3/V4 obviously ). I just wasn't sure if the grounds between the jacks would be tied together as well. It would seem odd that they wouldn't be but I never underestimate the ability of a designer to outclever themselves.

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    As far as your use is concerned, A floating ground and all tied to a common ground works exactly the same. The only thing that prevents being able to tie grounds is when two grounds are tied to a different reference, which would create a circulating current. If they are floating, the reference ground is constant the moment they are tied.

    With that said, I just checked my unit and discovered that all of the internal ports and any ports in a VDM are tied to aquabus negative. I was not expecting this result as that is a huge no-no in the oil and gas world and the utility industry in PLC and RTU controllers. In those areas, the shield on the cable is tied to earth ground and the positive and negative of all analog outputs are floating.

    You might be an engineer if...You have no life and can prove it mathematically.

  7. #7
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    I did not expect those ports' grounds to be tied to anything other than each other. I would have expected the breakout box ground and the 0-10V port grounds to be entirely separate on the main unit but maybe that's not quite the case. Does that also mean it's possible that multiple VDMs could share the same ground via the aquabus?

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  8. #8
    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by shoggoth43 View Post
    I did not expect those ports' grounds to be tied to anything other than each other. I would have expected the breakout box ground and the 0-10V port grounds to be entirely separate on the main unit but maybe that's not quite the case. Does that also mean it's possible that multiple VDMs could share the same ground via the aquabus?

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    Yes. There is continuity between the VDM grounds, the base unit varspd grounds, and aquabus negative at all points I probed.

    You might be an engineer if...You have no life and can prove it mathematically.

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