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  1. #11
    On the actual function of enable pins, a useful way to use them is to position work on the machine, jog the tool to your desired reference point, hit the disable switch and jog the controller to the matching position on the path display without moving the steppers. You could manually position the machine while the steppers are off if it has handwheels,

    - Nick
    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

  2. #12
    There is a big difference between PAUSE and emergency STOP. If everything goes to hell in a handbasket I usually retreat to the safety of the mains socket and kill the power there. This does preclude braking the spindle at the VFD but it is comforting to know everything will soon come to a halt without removing any more fingers.
    Pause OTOH implies a restart so it is purely a software driven thing which involves looking in to the G code future and creating a plan to get everything back up to speed. A well written pause is a joy to behold and well worth playing with

  3. #13
    Pause OTOH implies a restart so it is purely a software driven thing which involves looking in to the G code future and creating a plan to get everything back up to speed.
    Why should a pause require a restart as you should just be able to do a resume with no problems. A pause is generally a controlled stop as apposed to an emergency stop which always requires a rehome etc.
    ..Clive

  4. #14
    Quote Originally Posted by Clive S View Post
    Why should a pause require a restart as you should just be able to do a resume with no problems. A pause is generally a controlled stop as apposed to an emergency stop which always requires a rehome etc.
    Sorry I should have said UNPAUSE. I award stepper motors a speed at which I can start or stop them without losing steps. Once beyond that speed pausing and unpausing become interesting. It's tricky keeping everyone in synch. I have written it twice, once in Z80 assembler and once in C.
    Last edited by Robin Hewitt; 22-08-2016 at 10:53 AM. Reason: missing gerund

  5. #15
    Quote Originally Posted by Robin Hewitt View Post
    Sorry I should have said UNPAUSE. I award stepper motors a speed at which I can start or stop them without losing steps. Once beyond that speed pausing and unpausing become interesting. It's tricky keeping everyone in synch. I have written it twice, once in Z80 assembler and once in C.
    I had forgotten that you write your own control code and don't use Mach or Linuxcnc
    ..Clive

  6. #16
    Quote Originally Posted by Clive S View Post
    I had forgotten that you write your own control code and don't use Mach or Linuxcnc
    That was unexpected. I thought the only person who listened to me was my wife, one word out of place and her jaw starts to flap.

  7. #17
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 3-4 years. Has a total post count of 749. Received thanks 104 times, giving thanks to others 5 times.
    Editing a post because of a missing gerund was pretty unexpected!

    But back to topic - in an emergency (about to smash cutter into clamp, body part in imminent danger...) you want the machine to stop with 100% certainty and as quickly as possible. So you won't trust motion controller firmware, cutting power to driver power supply probably won't stop the machine immediately as you need to wait for output caps to discharge, and removing driver enable might not brake motors. Could cut power to drivers on output side of PSU but need chunky and reliable relay as you are switching high DC currents (possible contact welding?) and still lose braking. Could put something (TTL gates? Another relay?) in line with step signals - four of them, in my case.

    This is getting a bit silly! In my case, the Pilz device sends e-stop to CSMIO (manual says this has very fast response) and cuts mains to driver PSU (via secondary relay). These use high-reliability n/o Pilz contacts. I am also using the auxiliary n/c contact (not high-reliability) to switch the enable signal. This is for convenience as the drivers are effectively active-low on the enable input so I need to put +5V on them to disable. So, I have two not-absolutely-reliable stopping mechanisms but which are independent so one should work when needed with cutting driver power as a slower-acting backup, but not clear at the moment if I shall get motor braking. Safety is such a compromise...

  8. #18
    In my experience cutting power to the power supply does not make the machine run on more than a few m/s before the caps run out of juice
    ..Clive

  9. #19
    Quote Originally Posted by Neale View Post
    Safety is such a compromise...
    One of your primary E-Stop circuits should reliably control the spindle and effect an E-Stop with braking (if available) using it's controller. ;-)
    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

  10. #20
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 3-4 years. Has a total post count of 749. Received thanks 104 times, giving thanks to others 5 times.
    The Huanyang VFD is controlled by the CSMIO and I have been assuming that this will stop on e-stop although I have not checked this. However, I do have a primary Pilz contact going spare and I could wire the VFD run signal via that for belt-and-braces. I have more-or-less finished the control box, apart from some small odds and ends, but the machine isn't quite at the same state. Once I have limit and e-stop switches fitted and wired, I shall be going through the safety functionality that I have. For example, I haven't yet checked the VFD braking characteristics and tuned things like deceleration.

    When I say that safety is a compromise this is, obviously, I hope, tongue-in-cheek but we do have to be sensible about this. I am building a hobby machine for a home workshop, and not expecting idiot bystanders to wander by and poke fingers in it. However, I am also moving from the mark 1 built from MDF which is just about strong enough to stand up to its own weight(*) but would self-destruct in the case of any foul-up, to the mark 2 which is all welded steel, including gantry, and could do itself and anyone in its path serious damage. So, for example, accessible e-stops and limit switches all round, but no "open door" detector for the control box. Just trying to steer a sensible course between extremes.

    (*) I exaggerate - in fact, it is not quite strong enough to stand up to its own weight...
    Last edited by Neale; 22-08-2016 at 05:19 PM.

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