E-Stop Hard Wire and to Software?

[Sanghera]

Hi all,
I was just wondering how you would wire the E-Stop to the PS Line and let the software know that it has been triggered. I was thinking of just manually connecting an extra limit switch to the E-Stop Button but I don't know if that would be very good. It will probably be 12 or 24 Volts coming in, so I don't think that this can be just put into parallel port input. I have heard about this on some other threads aswell.
Thank for the help.
I really appreciate it.

[HuFlungDung]

You can use an auxilary circuit on a second set of contacts on the Estop switch. This way, you don't need to use the higher voltage circuit on the main set of contacts.

[CNCPlastic]

Get yourself a relay, I tapped a 5vdc main from my PC power supply across the relay for my e-stop which routes back to the PC with the logic 5vdc = good to go, 0vdc = estop. I used a 4 pole double throw relay I purchased at Grainger. When I hit my estop "everything" goes to zero volts, mill, all the electronics, the servos, the stepper, the whole works. I did use a solid state relay for the mill motor though as its 2hp and 240vac.

The 4 pole relay is rated for 120vac, I brought the 120vac mains in across that and then to the power supplies for the servos and the big stepper. Theres also a big green power on button and a power on green light wired in the mix. Plus for added safety, a on/off button for the mill motor. I did not want my computer in total control over turning the spindal on/off. This way I can turn it off mechanically and not worry when I'm changing an end mill or working around it.

[Sanghera]

Ok. So basically you have a main E-Stop switch that may be only five volts, and when you hit this switch the computer knows and sets the relay off so everything turns off?
And for HuFlungDung's answer, what kind of auxilary circuit are you implying?
Thanks for all of the help guys.
This is great.
I really appreciate it.

[sol]

I think what CNCPlastic means is he has one relay that has 4 sets of switches in it; one switches low voltage and tells the computer to E-Stop, and the others are higher voltage which kill the router, servos etc. That way when he hits one e-stop switch it activates one relay which controls 4 separate circuits.

[CNCPlastic]

Sol's got it right! The low volt (5vdc) switch on the relay is only 1 of 4 e.g. 4 pole double throw (4 switches). The 5vdc switch also trips the solid state relay on/off so its doing double duty. Also I had to put a resistor between the 5vdc and pin 15 which I'm using for my e-stop to keep the printer port from sucking down too much juice. The whole mess took quite a while to figure out.

[tachus42]

+5 IN---------- N/O-----------------------------
| | |
| | |
|----------RST----------------- | |
| | |
__ Coil EStop
Diode ^ | |
| | |
GND---10 Ohm------------------------------------
If the bad asci art makes any sense this is one way to wire a relay with other Normally open contacts in series with the other power supplies you want to control and a Normally closed contact to the Pc Estop. The switches are normally open . At power on you need to press the Reset switch briefly to get the relay to latch on. Hitting the estop switch shorts the relay coil turning it off and killing the power. The 10 Ohm resistor prevents the power supply being shorted and the diode kills inductive spikes from the coil.

[tachus42]

Should have previewed that one. I'll post a better diagram shortly

[tachus42]

This should be better

[Bloy2004]

Originally Posted by sol That way when he hits one e-stop switch it activates one relay which controls 4 separate circuits.

Do you mean that when he hits the e-stop it DE-activates the relay?
Could you run through the events that occur when the mechanical e-stop is "hit"?
I'm still confused ...
John

[sol]

Yes, perhaps CNCPlastic can clear this up...but it is a double throw relay so the design could be either way (coil activated or deactivated) by hitting the e-stop.
It would be safer for the relay's coil to be on while everything is running and for the e-stop switch to cut the coil off. Perhaps that is the way it is...?

[tachus42]

My description is a bit confusing. The relay needs to be activated ( by pressing the reset switch ) before power is supplied and the machine comes out of e stop. Hitting Estop deactivates the relay and cuts power.