[JohnLucas]

Mach 3 default setup (as supplied for Taig) senses eStop on parallel port Pin 10.

I'd like to install an external eStop push button but don't really want to break out Pin 10 from the controller box. I can easily connect a switch to a pin on a second parallel port and re define it in Mach3.

Does anyone know if the Taig controller ever uses the eStop wired to Pin 10? If it does I will have to wire into the controller box. Thanks.

[Fastest1]

What difference does it matter which PP you get it from? You still will have to make and break a connection for it to work. The Taig doesnt have an E stop?

[JohnLucas]

What difference does it matter which PP you get it from? You still will have to make and break a connection for it to work. The Taig doesnt have an E stop?

I have to admit that I have jammed a feed and this causes Mach to stop with the reset button flashing. I don't know if this is accomplished by the controller flipping line 10. If it is then not a good idea to change.

[Fastest1]

I have to admit that I have jammed a feed and this causes Mach to stop with the reset button flashing. I don't know if this is accomplished by the controller flipping line 10. If it is then not a good idea to change.

By "jamming a feed" do you mean stalling the spindle so the end mll or tool isnt spinning? Do you run servos or steppers with encoders? How would Mach know if the spindle was stalled and stop? You havent pressed the E stop? Pin 10 the way I understand it is the physical connection to keep everything safe. You do not want an E stop to be software based. It should be a mechanical switch accessible from the machine that shuts off pin 10 and preferably a contactor switch at the same time that kills power to the entire machine until the reset can be made. Btw IME, this always calls for a ref all and a go to zero command followed by a rewinding and regeneration of the toolpath. 99% of the time a new piece of stock too, unfortunately.

[JohnLucas]

I have the DLS system. When the carriage jams the stepper and shaft encoder disagree. Presumably the microcontroller in the control box recognises the discrepeny and stops the motor and drives. Mach 3 then flashes the Reset button and "emergency mode active" message.

The controller must have some way to communicate the problem to Mach 3 and my concern is this is done through the eStop on pin 10. If that is the case then I can't change eStop to another port.

Thanks for your continued help.

[Fastest1]

No but you could hook your e stop in line with it, sharing that pin. All it needs is a broken connection and all motion stops.

[JohnLucas]

Yes, I think that will be the safest. I looked in the controller and its pretty crowded so I think a breakout box is in order. Thanks.

[cameraguy]

The controller must have some way to communicate the problem to Mach 3 and my concern is this is done through the eStop on pin 10.

Anything is possible, but I would doubt it highly. The encoders have thier own pins and the data from them is most likely simply parsed internally to the program and a with discrepancy over a certain amount it simply shuts itself down. I seem to recall there are even tolerances that can be set as for when to trigger shutdown. No e-stop pin is needed. Surest way to check is simply to look into mach and see what the setup is configured like, and if pin 10 is even used.

Also, e-stop doesn't even have to have a pin assigned to it or go to the computer at all. Once I simply installed the e-stop switch to break the +5v power feed to the opto couplers. Pop the e-stop button on that unit and it cut all power to the opto-isolators. Nothing was moving after that, and at hardware level. No signal was getting through that to the hardware. Easiest way to do it, no screwing with parallel pins or software-level stops.

[Fastest1]

I was always told it was a wise idea to bring a contactor into play that cuts all power to the machine. No protection any other way.

[Jeff-Birt]

A real EStop circuit generally cuts power to all the things that move, i.e. the axis motor drives and spindle. If the power is not being cut to these devices then it is NOT an EStop.

The 'EStop' input to mach is only to tell Mach that an EStop condition has occurred. When mach sees this input it will stop outputting pulses and go into 'Reset mode'. This is no guarantee that your machine will actually stop moving. The spindle can keep spinning and there is a chance the axis motors will keep moving as well (especially if you have a larger machine with servos.)

As I mentioned before a 'real' EStop removes power to the moving parts and on larger machines may also activate brakes, etc. On the Taig usually removing AC power to the stepper drive box and spindle is adequate. If you look around you can find an industrial EStop switch with contacts that can be used to break 110V/220V @10A. You could place the switch in an enclosure along with a duplex outlet. The switch controls power to the outlet(s) and therefore shuts everything down. When the control is shut off mach 'should' be put into Rest/EStop mode.

[cameraguy]

The 'EStop' input to mach is only to tell Mach that an EStop condition has occurred...This is no guarantee that your machine will actually stop moving...there is a chance the axis motors will keep moving as well (especially if you have a larger machine with servos.)

I agree that a real E-stop cuts all power on bigger machines. Especially with servos it is necessary. My biggest machine actually has electromagnetic shaft brakes as well, and they kick in whenever power goes.
That being said, most little machines like Taigs only have a software stop, which is clearly not entirely safe. Without new equipment or modifications, my idea of killing the +5v to the opto stage using the same estop switch people already have hooked up is a much safer bet than keeping them software only, and with steppers will stop any possibility of a runaway machine, unlike pin 10. Does everything it needs to.
I agree getting magnetic contactors or some other system to cut power to everything is theoretically better, but most people don't want to go to the added expense of trouble. For a small stepper machine, switching one wire accomplishes effectively the same thing for $0 and a couple minutes time.