How to "turn off" and "turn on" axis soft limits??

All things related to the Centroid Acorn CNC Controller

Moderator: cnckeith

Post Reply
TopQuarkDoc
Posts: 20
Joined: Sun Nov 29, 2020 11:12 am
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: F045DA7F1D5B-0109191641
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No

How to "turn off" and "turn on" axis soft limits??

Post by TopQuarkDoc »

Hello All,

Two very simple questions:

How does one turn off the soft limits, and how does one then turn on the soft limits? This during operation, not via the wizard or through other static means.

For clarification of what is prompting this, is a desire to define the home location of an axis to be different from the initial home/proximity switch. The machine is driven to the home locations(M92) when it is started. Then before defining home (M26), the axis is commanded to the new position
(G90 G0 X-n.n) and the desired home position is defined (M26 /X). Everything then proceeds as desired unless I try to re-home the machine. When I reach the home switch for that axis, I receive a soft limit exceeded error. And yes, n.nn is less the the value of the soft limit.

The M94/M95 stuff in the beginning and end of the cncm.hom file does not seem to function as a way to do this.

I just want to know what, if there is one, M code will do this, or what assignment statement(s) needs to be inserted in the cncm.hom file to turn off and on the soft limits after the initial home sequence.

Thanks
cnckeith
Posts: 7164
Joined: Wed Mar 03, 2010 4:23 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: Yes
Oak CNC controller: Yes
CNC Control System Serial Number: none
DC3IOB: Yes
CNC11: Yes
CPU10 or CPU7: Yes
Contact:

Re: How to "turn off" and "turn on" axis soft limits??

Post by cnckeith »

during auto homing cycle Travel Limits are ignored by CNC12 since it doesn't know where machine home position is.
once home position has been determined, if there are values set the software travel limit menu, CNC12 uses those values to limit the motion of each axis to those values.

currently there is no G code to turn off Travel Limits. we will add this feature. i assume you are trying to make a Rack Mount ATC exclusion zone?

if you do not want to use travel limits set the values to zero.

(with upcoming v5.0 you can read and write these values using a macro).

user friendly graphical UI with teach in exclusion zones is on list for future feature.
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
cncsnw
Posts: 3763
Joined: Wed Mar 24, 2010 5:48 pm

Re: How to "turn off" and "turn on" axis soft limits??

Post by cncsnw »

As Keith notes above, the way you "turn off" software travel limits is to temporarily set both limits for an axis, to zero.

Another effective method, depending on your needs, is to temporarily set the limit for the direction you want to move, to a large enough value to allow the move.

You can do either of those things in a macro with current software. See CNC system variables #23501 - #23508 and #23601 - #23608 in the operator's manual. The macro should restore the normal/correct travel limit values as soon as the move is done.

Be aware that this is a risky practice, because if you interrupt your macro (e.g. Cycle Cancel or Emergency Stop) while it is running (i.e. before it has a chance to restore the travel limit values), then you will be left without travel limits thereafter.
TopQuarkDoc
Posts: 20
Joined: Sun Nov 29, 2020 11:12 am
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: F045DA7F1D5B-0109191641
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No

Re: How to "turn off" and "turn on" axis soft limits??

Post by TopQuarkDoc »

Gentlemen,

Thank you for your replies. This is the information for which I was looking.

I have found the referenced variables in both the operators manual and the PLC programming guide.

A couple more simple question dealing with this.

I assume the values are floating point, right?

And second, based on Keith's reply I take it the following sequence is what is happening with homing beginning at startup:

Home has not been set and the soft limits have not yet been sent from CNC12 to the MPU
Cycle Start invokes the cncm.hom macro
Machine is homed exiting the macro
Since machine is now homed, the soft limits are sent to the MPU from CNC12.

Now trying to re home the machine the soft limits have been enabled is screwing up my little change to try and redefine the machine 0,0 point.

There still is the point of when the limit is set to greater than the redefined home value, it still errors out when re-homing. This happens even if the soft limit is greater than 0.25" than the redefined home value.

Keith, this is an attempt to move the machine coordinate quadrant for X,Y from the third quadrant to the first quadrant. As this is the little mill I acquired from you, you will perhaps remember based on the location of the home switches, all motions from home (0,0,0) were in the negative direction.

Again, thank for your replies. I will give temporarily turning off the limits (then restoring them) a try in the next several days.

Tim
cncsnw
Posts: 3763
Joined: Wed Mar 24, 2010 5:48 pm

Re: How to "turn off" and "turn on" axis soft limits??

Post by cncsnw »

There still is the point of when the limit is set to greater than the redefined home value, it still errors out when re-homing. This happens even if the soft limit is greater than 0.25" than the redefined home value.
You have lost me there. I will wait until I see your report file to attempt any further comments or suggestions.
cnckeith
Posts: 7164
Joined: Wed Mar 03, 2010 4:23 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: Yes
Oak CNC controller: Yes
CNC Control System Serial Number: none
DC3IOB: Yes
CNC11: Yes
CPU10 or CPU7: Yes
Contact:

Re: How to "turn off" and "turn on" axis soft limits??

Post by cnckeith »

Tim,
hello.
on this machine the home switch physical location determines which quadrant the machine is working in when you use a standard home file.
start a photo album of the project, post link to photo album here and upload a sketch or photos of where the switches are located so we can follow along and give you good advice.
there is no need to defeat travel limits with this type of machine.
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
TopQuarkDoc
Posts: 20
Joined: Sun Nov 29, 2020 11:12 am
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: F045DA7F1D5B-0109191641
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No

Re: How to "turn off" and "turn on" axis soft limits??

Post by TopQuarkDoc »

Hello Gentlemen,

So first item:
This suggestion didn't work.
cncsnw wrote: Mon Feb 06, 2023 6:37 pm Another effective method, depending on your needs, is to temporarily set the limit for the direction you want to move, to a large enough value to allow the move.
cncsnw wrote: Tue Feb 07, 2023 2:25 pm
There still is the point of when the limit is set to greater than the redefined home value, it still errors out when re-homing. This happens even if the soft limit is greater than 0.25" than the redefined home value.
You have lost me there. I will wait until I see your report file to attempt any further comments or suggestions.
Second item:
I'm modifying the standard home file to change the quadrant. This works great except on a re-home.

Code: Select all

N100 ;Check for open home switch
IF !#[50000 + #9822] THEN M225 #100 "HomeAll switch tripped!!!\nPlease clear before Homing.\n\nPress Cycle Cancel to end Homing"
IF !#[50000 + #9822] THEN GOTO 100

;Disable all limits
M94 /101 /102 /103 /104

;So this is where I'll copy the soft limits to local user variables
;then set the soft limits to zero

;Perform Homing commands
M92/Z L1
M26/Z
M92/Y L1
;G91 G0 Y-3.8 F5  ;Fails here with Y soft limit = 4.0 on re-home (VCP button)
M26/Y
M92/X L1
;G91 G0 X-7.3 F5  ;Fails here with X soft limit = 7.5 on re-home (VCP button)
M26/X

;Here I'll reset the soft limits to the prior values.

;Enable all limits
M95 /101 /102 /103 /104

Currently I've started the final rewire on the machine, and I'm keeping a photo journal for later posting to help others with this type of conversion. The machine worked well on a multi-axis dry run with a test part that I modeled and for which I generated G-Code (21347 lines), after some jiggering of several lines to define the work envelope. I still have to work on the spindle, but that comes after completion of non-bench test wiring (it's a rats nest at the moment.) - I'll update this post in several days when every thing is back together.

Thanks
Post Reply