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Thread: e stop energizing

  1. #1
    Join Date
    Aug 2017
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    Question e stop energizing

    Had some lasers set up on a 3pin, e-stop chain. The last laser did not react to the estop being hit. The run was going around a lot of other energized cables.
    Are estops NO or NC normally closed? I thought they were usually closed, and the mushroom button would break the circuit when hit. Is it possible that laser somehow ended up being in an energized circuit?

    I want to learn more about Estops, any suggestions for reading? I keep accidently coming upon other e stop like machinery

  2. #2
    Join Date
    Oct 2010
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    Every manufacturer does this differently.
    Most I have seen just do a NO contact, that is bad as everyone that has knowledge in machine safety can confirm.

    I have seen that Live Lasersystems does stuff differently, they offer a system that they call "AIS". They seem to do something active inside there e-stop boxes, otherwise they could not have multiple boxes and have some sort of cable short/open detection.
    Have a look here: http://www.evil-lasers.com/faq.html

  3. #3
    Join Date
    Aug 2017
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    Anyone know if kvants 3 pin e stops are Normally Open?

    Would like to open one and check out how the wiring works

  4. #4
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Anything but N.O. I last had one open two years ago at a friend's and the board is rather sophisticated. Don't have my notes on that one anymore.

    Steve
    Qui habet Christos, habet Vitam!
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  5. #5
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    All of the E-stop circuits I'm familiar with (both for lasers and for other equipment) are normally-closed circuits that must be OPENED to trigger the fault or stop condition. This increases safety, since a loss of power will automatically trigger the E-stop, and any break in the cable (or even unplugging the cable) will also trigger the E-stop.

    If you had a normally-open circuit that had to be closed to trigger the E-stop, there would be no way to know if the cable became disconnected. You might THINK that everything is safe, right up until you attempted to trigger the E-stop and realized that you couldn't do so because the cable was no longer connected to the projector. Not good.

    There are a few different methods to connect multiple projectors to a single E-stop switch. Some manufacturers use a master/slave arrangement; the projector that has the E-stop switch connected is the master, and all other projectors are daisy-chained to it as slave units. I've also seen systems that use a hub and spoke arrangement where each projector connects to a central E-stop hub, which then has a single cable running out to the E-stop switch itself.

    If you are looking for further inspiration, you may want to read through the user manual for the Stanwax ILDA Interface board. Along with it's other features, this very popular ILDA breakout device supports a standard interlock circuit, an E-stop circuit, and a Class IV reset mechanism to make it easier for do-it-yourselfers to increase the safety of their home-built projectors. Note in particular that the 9-pin interlock connector on the board allows for both single-projector operation and the daisy-chaining multiple of projectors, all while using just a single E-stop switch.

    Adam

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