Axis, joints and soft limits confusion.

Hi guys,
For the last two weeks, I've been trying to do a basic task for most of the users (load up a tool) but I've been struggling with this error:
"Linear move on line -1 would exceed joint 2's positive limit"

What I do is: home the machine, lower the spindle until it almost touches the part, touch off the Z axis.
Then I go in MDI and type M6 T1 G43, to load the tool 1 from the tool library. Once I try to execute this command, I get the error described above, and nothing happens.

After some discussions with a guy from Germany (youtube user talla83), he sent me a print screen with his ini file for the Z axis and I've begin to doubt that my settings are correct.
Here is what I have:

HOME = -10.0
MIN_LIMIT = -365.0
MAX_LIMIT = -5.0
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 41.666667
HOME_LATCH_VEL = 0.500000
HOME_FINAL_VEL = 0.000000
HOME_USE_INDEX = NO
HOME_IGNORE_LIMITS = YES

What I'm trying to achieve:
I have considered the point where the switch is located as 0, so HOME_OFFSET = 0. On my machine, the limit switch is located on upper point of the Z travel, the positive travel direction.
After the machine is homed, I tell the Z head to go down 10mm from where the switch is located.
I know what my travels are, so by setting the MAX_LIMIT=-5, I avoid bumping into the limit switch due to overshooting when jogging toward positive direction. By setting the MIN_LIMIT = -365, I want to instruct the machine, how low can it go, from the limit/home switch that was used for homing.

After its homed, I can jog only between MIN and MAX, so I cannot trip the switch.

After talking with this german guy, I have noticed that on his machine, the limits are:
MIN_LIMIT = -278
MAX_LIMIT = 58
HOME_OFFSET = 0

So his settings are respecting the following note that I've seen in the linuxcnc documentation, but I don't understand it.

Note
The home switch location, as indicated by the HOME_OFFSET variable, must be strictly within the soft limits. That is, MIN_LIMIT < HOME_OFFSET < MAX_LIMIT.

If the HOME_OFFSET is the position of the switch, then how would I not trip the switch when moving toward MIN_LIMIT or toward MAX_LIMIT?

If someone can enlighten me, I would be very grateful!

Linux CNC and other controls use software limit switch.

So if you command a move that would end up outside the travel it will give an error or alarm.


What are the coordinates of your tool change position?

My max is .01
Min -12
Home 0.0
Home offset .1

Is it normal to call the g43 on the m6 line?

It sounds like of you are using g54 to position for the tool change it wants to travel 130mm up to do this.

Call up the tool then the offer and use g53 to position the tool change

In my current version I have not set a TOOL_CHANGE position, I tried to keep it as simple as possible until I nail down this issue.
Here is how my ini file looks like:

github.com/85vmh/LinuxCncConfigs/blob/1b...gs/SyilX7/SyilX7.ini

From the error message, I understand it has something to do with the softlimits, but I can't figure it out myself yet.

vmihalca wrote:

In my current version I have not set a TOOL_CHANGE position, I tried to keep it as simple as possible until I nail down this issue.
Here is how my ini file looks like:

github.com/85vmh/LinuxCncConfigs/blob/1b...gs/SyilX7/SyilX7.ini

From the error message, I understand it has something to do with the softlimits, but I can't figure it out myself yet.

There's no g20 in the program?

There is no program loaded yet, the machine is in metric, so its G21

I would remove the z value from g54 and see what it does

Delete the VAR files in the Mashine Folder and you are Fine

At trigger of the Z home switch, set this position to 5. (HOME_OFFSET)
MAX_LIMIT = 0.001 enables to retract G53 Z0. (5mm below the home switch)
(MIN_LIMIT could be set, just to reach machining area with a short tool)

MIN_LIMIT = -360 ; -365.0
MAX_LIMIT = 0.001 ; -5.0
HOME_OFFSET = 5 ; 0.000000
HOME_SEARCH_VEL = 41.666667
HOME_LATCH_VEL = 0.500000
HOME_FINAL_VEL = 0.2
HOME_USE_INDEX = NO
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 0

Try T1 M6 without G43 and check Z tooltable entry of this tool.
Do you have a toolseter? Otherwise its useless to use G43, just touch off to workpiece.

You are RIGHT!
This was the problem!
You saved my day!
Thanks!