Parallel port settings

While reading in order to solve the open joint problem with my machine limit/home switches I realized that one of my mistakes was that pins #11,12,13 were set as strictly "home" switches for axis X,Y, and Z.
I've reset them as "minimum limit / home', but I see no option for "all maximum limit' to assign to pin #10. I have a switch at each end of travel for all three axis. Is there an optional wiring method I'm missing?
Thanks

Hi

There is no option for that particular variation of switch grouping, but it does not actually make any difference.

You need to 'chain' your max limits switches in series on the NC pole of the switch. If any switch operates the circuit is broken.

Since you only get one wire out from this chain, you can assign it to Axis X Max Limit, or whatever you axis like.
When any max limit switch opens, motion will stop and an error is displayed.

Otherwise you need to edit by hand, create a max-limits signal and link each axis max limit to it.

The only difference will be that this will give you an error for all 3 axes instead of just X, but you still won't know which axis triggered it without looking.

If you set you soft limits correctly in your ini file it will be near impossible to activate the limit switches anyway.

regards

Would a better option be to install a new separate switch for each axis home and use the existing switches for limits?

Yes, that would be much better.

It is what I always do. If IO is limited it just takes 4 pins,one for all the limits in series and one each for the axes. (on a 3 axis machine).

Sharing limits and homing on one switch is always a kludge and often a problem.

It also means you can use comparatively cheap switches for limits, as precise position is not crucial and better more accurate and repeatable ones for homing.

regards

I have a dual port card that i can add to increase the pins. Would there be any benefit using this to give each switch a separate pin?
Also would this affect the latency value? My atom board currently test at 8700.

Hi

You could do that, declare each PCI parallel port as 'in' and get 16 extra inputs on top of the existing ones.

Depends what you would do with the signals when you got them.
Having 6 leds on a pyVcp panel telling you exactly which limit had tripped might look pretty, but it is nothing that a glance at the machine would not tell you.
The procedure afterwards is the same, back off the limit and re-home everything.

As I said, if your soft limits are right it will never happen anyway

There is also the matter of the cost and accomodating an extra parport cable and BoB to consider.

As far as latency goes, there has to be additional overhead to updating extra pins, but it will be so negligible as to not be worth bothering about in this context

regards