Another "what do I need" thread. Vmc retrofit

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02 May 2015 04:26 - 02 May 2015 04:29 #58308 by thewho
DOH! :silly: I should have figured that out myself.
Thanks!

Edit: Can I add pots for feed and spindle override in an easy way? Didn't see any option for that in pncconf.
Last edit: 02 May 2015 04:29 by thewho.

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02 May 2015 18:17 #58317 by thewho
Well that didn't work as I thought :( Anything above "OUTPUT_SCALE = 10.0" reduces the output voltage.
So I guess I need some scale thingy to my .hal file anyway.

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02 May 2015 18:35 #58318 by andypugh
It should work. Maybe you need to make the maxoutput and minoutput match?

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02 May 2015 18:49 #58321 by thewho
That only limits the output voltage.
I'm having a another funny problem, when I enable the spindle in Linuxcnc the output reads -0.1V so the spindle slowly rotates ccw.

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02 May 2015 20:54 #58322 by PCW
Like Andy said if, you have a say 3000 RPM spindle you must set:

#********************
# Spindle
#********************
[SPINDLE_9]
ENCODER_SCALE = 4096.0
OUTPUT_SCALE = 3000
OUTPUT_MIN_LIMIT = -3000
OUTPUT_MAX_LIMIT = 3000

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02 May 2015 22:12 #58324 by thewho
Worked like a charm :laugh:
I was so sure it was output voltage range.

Any easy way to adjust zero? When I enable the spindle there is 0.1V on the output. And that offsets the whole scale, -9.9V <-> 10.1V

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02 May 2015 22:28 - 02 May 2015 22:54 #58325 by PCW
7I77s analog output offset should be less than 10 mV

I would disconnect the output from the spindle and test again by measuring the
output at the 7I77 in case there is some interface issue (also check your voltmeter)

If you have a 100 mV output offset direct from the 7I77 this indicates a problem with the 7I77

Note that analog spindles that do not have circuitry to disable the drive
below a certain input voltage will always tend to creep when enabled since
the offset is never 0 (the same goes for analog servo drives)

Edit:

I also note that the spindle enable hal wiring is not right (this is a pncconf bug)

net machine-is-enabled => hm2_5i25.0.7i77.0.1.spinena

should be

net spindle-on => hm2_5i25.0.7i77.0.1.spinena
Last edit: 02 May 2015 22:54 by PCW.

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02 May 2015 23:44 #58329 by thewho
Did a bit more measuring and found something strange :huh:
There is 0.23mV on the 7i77 output and 104mV on the other end. Guess there is something funny going on with the cable i'm using.
That's also something I didn't suspect as I'm using a shielded cable that is connected to grounded only in one end.

Well well, gonna replace it and see if that helps :)

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02 May 2015 23:49 #58330 by andypugh

Any easy way to adjust zero? When I enable the spindle there is 0.1V on the output. And that offsets the whole scale, -9.9V <-> 10.1V


It probably doesn't actually matter.

Normally you would set things so that the spindle drive is not enabled when the spindle is off, so it probably doesn't matter.

In orient mode the PID will correct for the offset.

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03 May 2015 00:02 #58331 by thewho
No not now when I changed the spindle enable as PCW said.
But 0.1V is still 50rpm off target so it's nice to get rid of that.

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