http://www.pilz.com/products/control_communication/safety_relay/index.en.jsp
(first hit off google)
Basicly they are a relay, with some aditional circuitry inside so that
bad things can't happen.
if you have a glitch in the safety circuit, the safety relay opens and
stays that way until you reset it
But there are various kinds, with various inputs/connection circuits.
Regards,
Alex
On 4/13/2010 1:01 AM, Neil Baylis wrote:
What's a safety relay? Is it a particular kind of relay?
Neil
On Mon, Apr 12, 2010 at 2:51 PM, Alex Joni<alex.j...@robcon.ro> wrote:
Just use a safety relay for this, no need to reinvent the wheel..
Regards,
Alex
On 4/12/2010 10:10 PM, Neil Baylis wrote:
OK, thanks. I guess they don't exist.
I guess what I'll do is to add a circuit that requires the e-stop
button to be pressed before a fault condition can be cleared. Then I
have no choice but to twist the e-stop before resuming.
Thanks,
Neil
On Mon, Apr 12, 2010 at 11:32 AM, Jim Fleig - CNC Services
<j...@cncservices.ws> wrote:
Hi Neil,
I believe Eric is correct. After 30 years in industry (the last 20
specifically with CNC) I have never seen what you are describing. As
Eric
mentioned, a relay that must be activated by a reset switch would do the
job. Reset switches for this purpose I have seen and included in some of
the retrofits that I have done.
Have a good day,
Jim
----- Original Message -----
From: "Eric Keller"<keller...@gmail.com>
To: "Enhanced Machine Controller (EMC)"<emc-users@lists.sourceforge.net>
Sent: Monday, April 12, 2010 2:01 PM
Subject: Re: [Emc-users] Emergency Stop switch
My guess is that a switch with an actuator in it would be so expensive
that nobody has ever bothered to market one. I think your best bet is
to have a self-powering relay that can only be turned on by a
momentary switch.
Eric
On Mon, Apr 12, 2010 at 1:53 PM, Neil Baylis<neil.bay...@gmail.com>
wrote:
Thanks Jim,
I understand how to set up such a failsafe circuit. But in addition, I
want the actual e-stop switch to activate and latch, so that
regardless of whether the computer generates a fault condition, or I
do it myself, I still have to manually release the switch before
resuming operation.
Neil
On Mon, Apr 12, 2010 at 10:39 AM, Jim Fleig - CNC Services
<j...@cncservices.ws> wrote:
Hi Neil,
Setup a failsafe circuit with the connection passing through the E-stop
contacts energizing a relay. If anything in the series circuit becomes
open
(E-stop button, relay contacts in E-stop circuit, overtravel limit
switch
contacts, etc.) the functions dependant upon that circuit being closed
stop
functioning.
Someone may have a schematic example to share. If not, email me and I
will
send you an example.
Have a good day,
Jim
----- Original Message -----
From: "Neil Baylis"<neil.bay...@gmail.com>
To:<emc-users@lists.sourceforge.net>
Sent: Monday, April 12, 2010 1:19 PM
Subject: [Emc-users] Emergency Stop switch
I'm looking to source an e-stop switch. I have some already with the
big red mushroom button that latches when you press it, and must be
turned to release. This is good. But what I want is a switch that can
also be operated by a signal from the computer. So if the computer
detects an e-stop condition, the mushroom button would pop down, just
as if I had pressed it by hand. I would drive it from a digital out,
obviously.
Does such a thing exist, and can anyone point me at a source?
Thanks,
Neil Baylis
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