Author Topic: E-stop, combining switchs and opto islolators in series configuration?  (Read 1030 times)

0 Members and 1 Guest are viewing this topic.

Offline Campgems

  • Holding
  • Posts: 2
    • View Profile
I currently wiring up a new Taig Mill.  The Steppers are driven by Parker Compumotor OEM 750's and I would like to use the Fault Out opto isolators in the 750's in series with limits and E stops switches to trigger and E fault  input to Mach3.  Active low and the BOB has puldowns on the inputs.  I am wondering if there would be enough voltage drop across the four Opto isolators to cause problems, not in an E-stop condition, but causing false E-stops   I'm using an ESS and CNC4PC ESS BOB that I modified to be cable connected to the ESS vs direct plug.  Mach3, Win XP.

Thanks
Don

Offline joeaverage

  • Active Member
  • Posts: 4,511
    • View Profile
Hi,
with the ESS you have lots of inputs so you don't have to combine by wiring in series or parallel the fault switches.

Assign one input pin to each fault switch and program Mach that any of those pins is to cause an Estop.

Craig
My wife left with my best friend...
     and I miss him!

Offline Campgems

  • Holding
  • Posts: 2
    • View Profile
Craig, thanks for the reply.  It is something I've been considering, but wasn't to happy with the idea. 

This is an issue I've been pondering for several months.  After posting the question, I realized I was worried about voltage loss with a 5VDC input, but the drives will support a much higher voltage through the opto isolators, so adding a 12vdc supply will resolve any voltage drop.  Now I'm considering using the higher voltage to hold a relay transferred and with a drop use the NO points to hold a + signal to Mach3 E-stop inactive and a drop to trigger it 

I don't like the idea of some dozen or more inputs,  when one will do.  I think I caught this one soon enough that I don't need a Revision 3 of my BOB wiring,  Hope so anyway.

Don

Offline joeaverage

  • Active Member
  • Posts: 4,511
    • View Profile
Hi,

Quote
I don't like the idea of some dozen or more inputs,  when one will do.

Why? I have a three axis machine and so I have three roller plunger microswitches for home switches. I have attached each switch to its own pin, no problems. Homing is absolutelty effortless.
Now go and compare that strory on the forum to all those people that try to combine limit and home switches, often all in series and end up crashing instead. Once upon a time when everyone had one
parallel port and only five inputs it made sense. Now it not only does not make sense it increases the risk of confusion and crashes.

All industrial machines have separate home switches....and separate limit switches as well, that's nine switches and nine inputs. Why would Haas, Fanuc and the likes do that if it were not a good idea.
That's like saying that the Model-T-Ford had trembler ignition so I going to use trembler ignition on my V6 sports car of 100 years later!

Craig
My wife left with my best friend...
     and I miss him!