Reverse spindle no pwm

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20 Mar 2012 05:58 #18657 by grandixximo
I'm trying to get a spindle work in both directions, but i do not get any pwm output when i start the spindle in M4

i'm using pdm mode with no offset and a scale of 18900

max-dc 0.4

the spindle at maximum speed is roughly 6500RPM

i do not use outputs to turn the spindle on, the spindle is stopped at pwm 0

Also i am using the soft start hal lines

and i only connected net spindle-rev motion.spindle-reverse => parport.0.pin-17-out


any help???

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20 Mar 2012 07:27 #18658 by grandixximo
Attached i made a simple stepconf to demonstrate what i mean, check pin curr-dc of pwmgen and notice that you get a value only when the spindle is going clockwise nothing when you go ccw

File Attachment:

File Name: jinjin.stepconf
File Size:8 KB
Attachments:

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20 Mar 2012 14:59 #18665 by grandixximo
Resolved using abs component in hal to have the spindle speed always positive.

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20 Mar 2012 17:10 #18670 by BigJohnT
Replied by BigJohnT on topic Re:Reverse spindle no pwm
This has come up before, I wish I could figure out a good place in the manual to say something about this...

John

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20 Mar 2012 17:27 #18672 by PCW
Replied by PCW on topic Re:Reverse spindle no pwm
Isn't this a bug/ommission in stepconf that it does not set the PWM mode correctly?

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21 Mar 2012 01:57 #18675 by grandixximo
I think a good place to add this in the docs would be here

linuxcnc.org/docs/html/examples_spindle....#Spindle%20Direction

it says that all you have to do is connect a pin to have the spindle running in the opposite direction, but actually if you don't hijack the spindle speed out with abs you will not get any frequency out of pwmgen

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21 Mar 2012 03:52 #18680 by cmorley
Replied by cmorley on topic Re:Reverse spindle no pwm
Are we saying that stepconf should always use absolute component with the spindle PWM?
This would seem to be right but I have not dug in to see yet.

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21 Mar 2012 04:24 #18681 by grandixximo
Yeah stepconf should always use abs with the PWM, it would make things easier when you add the direction of the spindle it will still work...

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21 Mar 2012 11:53 #18683 by BigJohnT
Replied by BigJohnT on topic Re:Reverse spindle no pwm
grandixximo wrote:

I think a good place to add this in the docs would be here

linuxcnc.org/docs/html/examples_spindle....#Spindle%20Direction

it says that all you have to do is connect a pin to have the spindle running in the opposite direction, but actually if you don't hijack the spindle speed out with abs you will not get any frequency out of pwmgen


Can you give me an example of using the abs and I'll add it to the docs as soon as I get past my dial up wows...

John

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21 Mar 2012 15:22 #18687 by PCW
Replied by PCW on topic Re:Reverse spindle no pwm
Is it really ABS thats needed or the proper PWM mode?
PWM mode 1 should do the right thing without adding any other comps
if PWM mode 1 does not do the right thing, the PWM comp needs to be fixed

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