RE: [CAD_CAM_EDM_DRO] The 250 byte packet viz. ESTOP

I have a completely different putlook on the E-Stop issue, if something is going wrong enough that I feel it's an emergancy to stop the machine, who cares if the machine knows where it is, if I'm about to lose a body part, the time it takes to reset up a wasted part is worth it. If you are only about to crash the head or the tooling into a part, then that really isnt an emergancy. And a regular stop should be used. An E-Stop should bring the machine to a halt immediately, it not sooner in the case of personal injury. To hell with the machine knowing where it is in relationship to the part.

E-Stop is a saftly feature, not something to be used to keep the head from crashing.

Stop button is used to keep machine from crashing.

Del


John Dammeyer <johnd@...> wrote:
Hi Wayne,

I was also just talking about informing the controlling PC that an ESTOP had
occurred. Back a long time ago when I worked The Netherlands the machines
we built shut down completely with an ESTOP. The ESTOP line controlled
power to the 3-phase power contactor relay. I believe that was the rule for
the equipment that went to the far east too.

However, there was always some discussion about whether an ESTOP should just
shut down power to all things that move and leave the PC active. But then
what if it's an electrical short circuit type issue with sparks flying?
Shouldn't ESTOP shut everything down? Tough call. I don't know if EU
legislation was changed to only shut down drive power and leave computers
active.

On my Lathe, the red mushroom removes power now! But once I wire up an ELS
to it, do I want to lose position info if I hit the ESTOP? I might at that
point, wire up a separate power switch that controls power to the low
voltage supplies and let the ESTOP shut down AC power to the spindle motor
and Stepper Motor Power Supply Transformer.

However, back to the subject, if the ESTOP is hit, it's nice if the PC stays
active and knows at what point it happened. For diagnostics perhaps....

John Dammeyer


Wireless CAN with the CANRF module now available.
http://www.autoartisans.com/products
Automation Artisans Inc.
Ph. 1 250 544 4950

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Wayne Weedon
> Sent: Saturday, May 20, 2006 4:52 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] The 250 byte packet viz. ESTOP
>
>
> John Dammeyer wrote:
>
> >Hi Mark,
> >
> >If the USB dongle is receiving 250 bytes every 10mS and
> checks the ESTOP and
> >limit switches every 40uS then even if there wasn't a
> immediate message to
> >the PC via USB to tell it that an ESTOP occurred worst case
> would still be
> >only 10mS.
> >
> >
> E-stop signal to the cpu should only be a signal to say E-stop has
> occured. Normally E-stops are hard wired externally, and any
> processor
> will have nothing to do with it.
>
> Drive(s) shutdown is all handled by the estop relay on all my
> retrofits,
> but then at least here in the UK it's a legal requirement to
> do it this
> way. I'd expect it's much the same elsewhere.
>
> --
> --------------------------------------------------------------
> -------------
> Wayne M Weedon Email: wayne@...
> Fdos Design Poole UK
> Tel +44-1202-677025 Fax +44-1202-770515 Mobile:
> 07774 439915
>
> Specialists in small batch & Production Mechanical/Electrical
> Engineering
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