E Stop

[Duc748]

Hi All,
Personally I prefer a mains voltage control circuit for the E Stop rather than software controlled by mach3.(software crash no E stop)
Just wondering is it possible for some way of telling mach that a E stop of this configuration has been pressed so as mach would stop running too?

Rick

[Hood]

I have that on all my machines (24v in my case) for the E-Stop string to contactors etc  My E-Stop switch however is double pole so I have one pole  for the 24v side and the other for the 5v to Mach.
If you have just a single pole E-STOP switch you could easily put a relay in the E-Stop string and have the contacts signal with 5v to Mach.
Hood

[Duc748]

Thanks hood for your advice.
My E Stop is a single pole and is the control circuit for the latching in on the contactor, I dont quite understand about the 5v signal you refer to..does this go open circuit with the e stop?? also is the 5v an input to mach?

Rick

[Hood]

As your E-Stop is just a single pole you could put a relay, with a coil of the same voltage as your E-Stop string, in series with the switch. That way the coil would be energised thus closing the relays contacts. The contacts of the relay would have the 5v signal to Mach, how exactly would depend on whether you have a breakout board (and which one)  or just connect direct to the parallel port.

Hood

[Duc748]

The contactor Im using is 3 pole and each pole is electrically isolated from each other...could I use one of those poles for the 5v instead of a relay??..or am I going of track here?
The breakout board is just a basic standard one.

Rick

[Hood]

You could but you would have to be careful that you dont pick up noise from the higher voltages on the other contacts especially so as your breakout board is not optically isolated.
Hood

[Duc748]

So a optically isolated bob would eliminate the electrical noise?
also is the 5v taken from the parallel port and fed back as an input to mach, or would I need a 5v power supply? The 5v is the part im unsure of.

Rick

[Hood]

The optical isolation would help more if you got any high voltage/currents on the wires as it should protect your port and pc from damage, then again PCs are probably that cheap now that its maybe not a huge concern.

Ok the 5v side of things would just work like any other input you have on your BOB, for example how are your limits wired, do they just come from the input, through the switch to the bobs gnd?

Hood

[Duc748]

Yes my limits are wired as you  pointed out..The way you have explained has now made it very clear for me to understand.
Thanks again Hood  (what would we do without the knowledge from people like you?)

Rick

[Hood]

Forgot to say best to use shielded cable to minimise the potential of picking up noise.

Hood