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  1. #1
    Hi all,

    Just wondering if it is necessary to use the enable pins, I notice a lot of setups do not use them. What is the purpose of them? Any drawbacks to not using them?

    Thanks

  2. #2
    Quote Originally Posted by ROBCNCAU View Post
    Hi all,

    Just wondering if it is necessary to use the enable pins, I notice a lot of setups do not use them. What is the purpose of them? Any drawbacks to not using them?

    Thanks
    They are not generally necessary to use them but they can be used to halt the drives from the motion controller via the BOB.
    ..Clive

  3. #3
    So it would be a good idea to use them then? It is only an one extra wire to hook up.

  4. #4
    Quote Originally Posted by ROBCNCAU View Post
    So it would be a good idea to use them then? It is only an one extra wire to hook up.
    Yes but stall detect would be a better option for me especially if you have a slaved axis
    ..Clive

  5. I use a Pilz safety relay which sends an e-mail stop signal to the motion controller, takes power off the driver power supply, and also removes the enable signal from the drivers. One of those should stop the machine! The safety relay is tripped by the e-stop switches and the driver fault signals which are all wired in series. There are enough relay contacts on the safety relay to do that so, as you say, for the sake of a piece of wire it's easy enough to do. I wanted to make sure that the stall detect would stop the machine as I am using slaved motors for the X axis.

  6. [Posted twice]
    Last edited by Neale; 21-08-2016 at 05:47 AM.

  7. #7
    Doesn't the EN pin free the motor so you can do a bit of manual positioning? If so it makes for a crummy emergency stop because there is no braking. OTOH if your drivers have no pattern memory and revert to a set home pattern when you switch on, then EN would be a good option if you wanted everything to cool down while you replaced a broken tool, went out to buy milk, fags etc.

  8. I hadn't thought of the possibility that the driver might remove motor voltage if not enabled. I can't see anything specific about this in the manual - going to have to actually test the hardware. I take the point about motor braking but I was influenced by a number of comments on this forum that you should not trust motion controller firmware for safety-critical functions like e-stop. Not entirely sure why not as we trust it to move each axis correctly and recognise limit switch inputs but there we are. So IF you don't trust the firmware and IF chopping power to the drivers will not have immediate effect, how do you stop the machine quickly? I'm particularly interested in avoiding damage if one of the slaved axis motors stalls. The manual does say that on stall detect, power is removed from the motor.

  9. #9
    I agree Neale the beauty of stall detect is that you have all the drives connected together so that if any one drive stalls they all stop and that will stop the gantry from destroying itself.
    ..Clive

  10. #10
    Quote Originally Posted by Neale View Post
    Not entirely sure why not as we trust it to move each axis correctly.
    We assume it will and we hope it does and that is usually the case but the E-Stop is there purely because we should be aware that the worst can happen and the way to make sure everything is guaranteed stop if we want it to is to have the best failsafe we can devise, and that is not the systems which will have failed in the worst case scenario.
    Last edited by magicniner; 21-08-2016 at 09:37 PM.
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

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