Help with ThirdAxisHomeLimitOK functionality

[martinbatts]

Dox say: ThirdAxisHomeLimitOK ==> One switch used as both a home switch and a limit switch for Axis #3 using one input per
switch

I have my Z Assembly setup for bench testing. I have two limit switches (one at each end).
I have the Wizard set for ThirdAxisHomeLimitOK set for Input3 (works ok at each end, manually tripping it)

I "assumed" that jogging in either direction would trip it, and then Acorn would back it off to clear the trip, but it doesn't. It remains tripped, with the whole system unusable, because I cannot even manually jog it to clear it.

I tried the LimitAll choice, with the same happening.
What gives?
Is Acorn actually backing it off, but not enough, and perhaps there is a setting to increase the backoff amount?

Help.

[cnckeith]

when are you jogging? before or after homing? what version of software are you using?
what does your home program look like? etc. need more info. post a fresh report.zip so we can see all this and a link to photo album of your machine tool

[martinbatts]

I’m not homing. I’m bench testing Z Axis assembly.
As I understand it Homing is like a needed and good practice because the Acorn doesn’t know where it is on bootup.
And the software travel limit only works if one Homes the machine so it knows where it is.

But that isn’t my question.
My question is does the Acorn back off after a tripped switch for ThirdAxisHomeLimitOk
And if it does is the amount configurable.

[tblough]

It backs off during homing. It does not back off when acting as a limit. Are there numbers or dashes on the DRO?

[cnckeith]

post photos of your home switches,
and explain why do you want to change the back off distance?
page 345 P180, but if you have to change this you should have a good reason.

[martinbatts]

So, maybe an explanation of my understanding on how it works will reveal my problem..
I assumed that jogging in either direction (both Z axis sides in series to an input with ThirdAxisHomeLimitOk), would trigger a stop, where the Acorn PLC would automatically back it off until cleared.
But, perhaps only the cncm.hom program with the M92/Z command, (which the dox say WILL back it off until cleared) does the backing off, and jogging it manually, perhaps does NOT back it off??
In which case, I guess I need to abandon ThirdAxisHomeLimtOk, use HomeAll and LimitAll, and put the 'Home' switches in series to the HomeAll Input, and wire the opposite X, Y and Z limit switches in series, and assign to a LimitAll input?? And then ALWAYS run the cncm.hom at startup?

Is this how it works?

[cnckeith]

if you are in bench test phase, watch martys video series he show and explains most all this stuff.

https://centroidcncforum.com/viewtopic.php?f=61&t=1449

[martinbatts]

It backs off during homing. It does not back off when acting as a limit. Are there numbers or dashes on the DRO?

Thanks, that answers my question.

And yes, I state in another response, that I am not running cncm.hom

I am installing a second 'limit' switch, just as a safety, for reasons given in the dox.

Cheers

[cnckeith]

let us know how you have it wired with a sketch or photo and post a fresh report.zip so we see how you have everything configured.
there are a lot of different limit and home combinations that work just fine, so there is no one right answer but, if you give us
a clear description of the function your are seeking we can advise you.
in general most users use one of these typical setups to save inputs for other uses

1.) HomeAll with three home switches for x,y,z and have the software travel limits take care of the other side of the travel.

2.)Wire six switches and use HomeLimitAll and wire all six switches into that one input. then the switches act as home switches during homing and act as limit switches the rest of the time.

easy peasy.

[martinbatts]

let us know how you have it wired with a sketch or photo and post a fresh report.zip so we see how you have everything configured.
there are a lot of different limit and home combinations that work just fine, so there is no one right answer but, if you give us
a clear description of the function your are seeking we can advise you.
in general most users use one of these typical setups to save inputs for other uses

1.) HomeAll with three home switches for x,y,z and have the software travel limits take care of the other side of the travel.

2.)Wire six switches and use HomeLimitAll and wire all six switches into that one input. then the switches act as home switches during homing and act as limit switches the rest of the time.

easy peasy.

That helps.
I guess the key thing I’ve learned is that I have to run CNC.hom at startup for this to work (and for the software limit to work)

Thanks