How do you use Soft Limits with Homing?
- mjohnsonsa
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16 May 2016 06:21 #74722
by mjohnsonsa
How do you use Soft Limits with Homing? was created by mjohnsonsa
I have combined limit and home switches for each axis. I have HOME set up for 0.0 on each Axis. The soft limit is always either equal to or inside the physical switch contact. This means when homing it gives a soft limit error because it has to pass the soft limit in order to trip the contact, If I move the soft limit outside of the contact, then it works fine but then the soft limit will never be used because the machine will always hit the hard limit switch before the soft limit. Utilizing home offset does no good because it offsets somewhere inside of the hard limit and then sets the home to 0. Now next time it homes, it has to go past the 0 to get to the limit switch. So you end up in the exact same situation. Any help is appreciated figuring out how to utilize both the benefits of soft limits as well as homing when you have combined limit and home switches.
Also, if I set offset, home, and max limit to 0, then it works about 50% of the time (I have to move the machine slow on approach)
Please advise. Thanks.
Matt
Also, if I set offset, home, and max limit to 0, then it works about 50% of the time (I have to move the machine slow on approach)
Please advise. Thanks.
Matt
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16 May 2016 09:23 #74730
by cncbasher
Replied by cncbasher on topic How do you use Soft Limits with Homing?
the problem is the combined switch approach , you have to allow the soft limit area access to the home switch .
ideally you want seperate home switches , makes life so much easier
ideally you should never hit the limit switches , as you say by having the soft limit inside of the limit which of course you can't do
i'd fit some extra switches for homing ,
ideally you want seperate home switches , makes life so much easier
ideally you should never hit the limit switches , as you say by having the soft limit inside of the limit which of course you can't do
i'd fit some extra switches for homing ,
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- LearningLinuxCNC
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16 May 2016 17:39 #74757
by LearningLinuxCNC
Replied by LearningLinuxCNC on topic How do you use Soft Limits with Homing?
I have the simplest system as far as home and limits. I have six limit switches all wired in series so that If any one breaks then the circuit is opened and the limit is triggered. I also use this same circuit for homing. I have no issue with soft limits and homing. I have my Home offset set so that it 0.1" away from the limit/home switch. This seems to do the trick. Attached is my INI file for your reference.
The following user(s) said Thank You: joekline9, mjohnsonsa
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17 May 2016 14:59 #74797
by andypugh
That doesn't add up. If the axis isn't homed then LinuxCNC does not know where the soft limits are. Are you sure you are not tripping the hard limit?
You [AXIS] sections in the INI should contain HOME_IGNORE_LIMITS=1
Also, possibly HOME_IS_SHARED=1
Replied by andypugh on topic How do you use Soft Limits with Homing?
This means when homing it gives a soft limit error because it has to pass the soft limit in order to trip the contact,
That doesn't add up. If the axis isn't homed then LinuxCNC does not know where the soft limits are. Are you sure you are not tripping the hard limit?
You [AXIS] sections in the INI should contain HOME_IGNORE_LIMITS=1
Also, possibly HOME_IS_SHARED=1
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