Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: oskie on October 07, 2009, 08:22:54 PM

Title: EStop won't work
Post by: oskie on October 07, 2009, 08:22:54 PM

I have wired a estop button to pin 10 and then to ground, when I close the circuit I am not getting it into estop.  Please help

Title: Re: EStop won't work
Post by: Chaoticone on October 07, 2009, 09:27:03 PM

Have you set up your estop in config, ports and pins, inputs? Have you checked your wireing and switch?

Brett

Title: Re: EStop won't work
Post by: Hood on October 08, 2009, 02:20:28 AM

Also best to wire as a normally closed circuit when doing limits or E-Stop, reason being is if you have it normally open and a wire breaks you will not know until you need to use it and it doesn't work. If you have it as a normally closed and a wire breaks then you know right away.
Hood

Title: Re: EStop won't work
Post by: Jeff_Birt on October 08, 2009, 09:31:35 AM

Also remember that the E-Stop input into Mach is to just let it know that an E-Stop occurred, you should not depend on Mach to stop the machine during an E-Stop.

Title: Re: EStop won't work
Post by: bill-the-cat on October 08, 2009, 10:27:10 AM

Quote from: Jeff_Birt on October 08, 2009, 09:31:35 AM

Also remember that the E-Stop input into Mach is to just let it know that an E-Stop occurred, you should not depend on Mach to stop the machine during an E-Stop.

If that's true, what DO you depend on to stop the machine?

Title: Re: EStop won't work
Post by: Jeff_Birt on October 08, 2009, 10:32:42 AM

That is true! The other parts of an E-Stop system depend entirely on your machine, drive, etc. Generally speaking an E-Stop condition will remove power to the drives (by switching off the AC to the power supply) and may also switch in braking resistors (for servos) and/or axis brakes.

Title: Re: EStop won't work
Post by: oskie on October 08, 2009, 11:07:07 AM

Thanks for the reply,  I guess I had it hooked up properly, must be a bad pin 10, moved to pin 12 an now it works.  Thanks

Title: Re: EStop won't work
Post by: Konrad K on October 08, 2009, 06:20:52 PM

Hi Oskie,

yes, my forespeakers are right: The emergency stop should work in a way that does not need the Software or even the Computer.   ;D

But remember: the parallel port is using TTL logic, so you have to provide a defined logic state to the pin, i.e. either 0 Volts or 5 Volts.

If you just connect a switch to the input pin and to ground pin, you can generate 0 Volt (switch closed) but with the switch open you generate an undefined state... there is only noise coming to the input pin, but no 5 Volts.

A simple solution would be a switch (connected to the ground), together with a pull-up resistor (connected to 5 Volt). (Computer ground, not the one from the drive power supply...) And only do this when you're sure what you are doing... especially the good old parallel port is very easy to damage.   >:D

See also:  
http://en.wikipedia.org/wiki/Digital_signal (http://en.wikipedia.org/wiki/Digital_signal)


(hope you don't call me a teacher  ;) )

Konrad

Title: Re: EStop won't work
Post by: oskie on October 08, 2009, 08:10:29 PM

I have a lot to learn, I was relying on Mach3 to do the estop.  I will redesign with a proper estop.  Thanks