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Homing isn't always required

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23 Jun 2022 02:00 #245639 by cprhodin
Homing isn't always required was created by cprhodin
My machine is using linear encoders for position feedback.  These encoders know whether or not they have been homed.  The home position of each access is only lost if the machine is unplugged.  How can I configure to skip homing when the axis is already homed?  Is this doable in the INI or HAL files?  Can it be done in the encoder device driver?

Chris

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23 Jun 2022 23:00 #245737 by andypugh
Replied by andypugh on topic Homing isn't always required
See "HOME_ABSOLUTE_ENCODER" in the INI config docs:

linuxcnc.org/docs/stable/html/config/ini...t__lt_num_gt_section

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25 Jun 2022 02:48 #245836 by cprhodin
Replied by cprhodin on topic Homing isn't always required
My encoders aren't actually absolute.  I still need to home them when first powered.  What I want to avoid is homing every time I start linuxcnc.
 

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25 Jun 2022 03:08 #245837 by andypugh
Replied by andypugh on topic Homing isn't always required
My lathe is very similar. (it isn't actually absolute but the resolvers are single-turn absolute, so with a normal shutdown position.txt is enough to make them absolute, most of the time).

You can have multiple INI files in a single config folder sharing HAL files. So I have two configs. One (default) assumes the abs encoders are right. The other homes conventionally to swiches when I notice that it's gone wrong.

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25 Jun 2022 22:13 #245886 by cprhodin
Replied by cprhodin on topic Homing isn't always required
Multiple INI files sounds like what I need to do. From the source code it looks like I need to set the joint homed flag. There isn't currently a way to do that.

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26 Jun 2022 00:15 #245890 by andypugh
Replied by andypugh on topic Homing isn't always required
You mean that you want to set things as homed without pressing the home button?

On my lathe I just put up with pressing the button. Nothing moves, it just immediately marks all joints homed.

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26 Jun 2022 00:35 #245891 by cprhodin
Replied by cprhodin on topic Homing isn't always required
The encoders have a status bit that indicates they have been homed. At startup I'd like to use it to set the axis as homed.

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26 Jun 2022 09:36 #245904 by andypugh
Replied by andypugh on topic Homing isn't always required

The encoders have a status bit that indicates they have been homed. At startup I'd like to use it to set the axis as homed.
 

You could use that bit to toggle halui.home-all.

linuxcnc.org/docs/stable/html/man/man1/halui.1.html

It's possible that simply netting them together will work, but I would rather expect that it would need to be used in conjunction with an and2 and an edge, to create a single pulse when the machine is turned on, if the bit is set.

linuxcnc.org/docs/stable/html/man/man9/and2.9.html
linuxcnc.org/docs/stable/html/man/man9/edge.9.html

Does this make sense or do you need a short HAL primer? 
 

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