Limit3 Usage/Configuration

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06 Feb 2022 04:29 #234080 by Thods1222
Hello all, I need a little help getting the limit3 functioning for my VMC spindle.  I have a Cincinnati Milacron Arrow 1000 that I am trying to get running. The spindle is controlled with a 15hp servo/servo drive. The drive tries to spin up the spindle super fast which results in it faulting out. The hardware I am using is a 7i92 coupled to a 7i77/7i70/7i71. I came across the limit3 and from the lathe case example it seems to be the ticket for me to utilize to slow the acceleration down to a manageable pace.  I am having a difficult time getting it set up right and could use some help making sure the syntax is right and the signal is moving appropriately through the logic. Attached are my HAL, INI and Custom HAL files that I am using. 

If there is a better function built into linuxcnc, let me know about that as well.  Mainly I am looking to slow acceleration and control deceleration without having to change parameters in the drive itself.
 

File Attachment:

File Name: Arrow_1000...2-05.ini
File Size:4 KB

File Attachment:

File Name: custom_2022-02-05.hal
File Size:8 KB

File Attachment:

File Name: Arrow_1000...2-05.hal
File Size:11 KB
Attachments:

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08 Feb 2022 23:45 - 08 Feb 2022 23:45 #234364 by Benb
Replied by Benb on topic Limit3 Usage/Configuration
Have look at these two links they show a motor soft-start examples using hal components:

linuxcnc.org/docs/html/hal/hal-examples.html
linuxcnc.org/docs/html/examples/spindle.html

Ben
Last edit: 08 Feb 2022 23:45 by Benb.

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09 Feb 2022 03:21 #234372 by Thods1222
Ben, thanks for the reply.

I looked at those examples and was having a hard time connecting the dots to get them linked up with my hardware. First I tried the spindle hijack and it didn't work. I came across the limit3 functionality and it seemed to be the ticket. I am new to computer coding in general and trying to teach myself as I go along...which seems to be a steep learning curve. 

In my HAL section for the spindle I have the following.

setp hm2_7i92.0.7i77.0.1.analogout5-scalemax [SPINDLE_0]OUTPUT_SCALE
setp hm2_7i92.0.7i77.0.1.analogout5-minlim [SPINDLE_0]OUTPUT_MIN_LIMIT
setp hm2_7i92.0.7i77.0.1.analogout5-maxlim [SPINDLE_0]OUTPUT_MAX_LIMIT

net spindle-output => hm2_7i92.0.7i77.0.1.analogout5
net spindle-enable => hm2_7i92.0.7i77.0.1.spinena hm2_7i92.0.7i71.1.1.output-04

loadrt limit3
addf limit3.0 servo-thread

setp limit3.0.maxv 100
setp limit3.0.enable true

net spindle-vel-cmd-rpm => limit3.0.in
net hm2_7192.0.7i77.0.1.analogout5 <= limit3.0.out

It doesnt give me any grief upon startup but I think I may have it not linked appropriately since the spindle seems to disregard the limit3 maxv.  I tried commenting out the "net spindle-output => hm2_7i92.0.7i77.0.1.analogout5" but that resulted in the spindle enabling and not moving to the commands. 

If limit3 isnt the best possibility if people have a better solution, I am all ears. I am hoping to crack this nut so I can get to linking up my tool carousel and trying to learn ladder for that piece.  
 

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09 Feb 2022 20:59 #234429 by Benb
Replied by Benb on topic Limit3 Usage/Configuration
Try entering a value for motor acceleration MAXA.

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