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Author Topic: Incorrect PWM Signal for Spindle  (Read 3043 times)

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Incorrect PWM Signal for Spindle
« on: March 21, 2013, 04:41:15 PM »
I have searched for a couple of days trying to figure this out on my own, but I have come up empty.

I have a Chinese VFD (it has been running well manually for over 2 years) that I have wanted to be controlled by Mach 3.

During the PMDX-107 Test, here is what I get:
24000 rpm = 10VDC
8000 = 3.344VDC

Mach3 Test
S24000 = 9.88VDC
S8000 = 3.34VDC

I have been looking around the net and haven't found anything that I can find at tweaking the voltages in Mach 3 so that they are correct.

My Spindle Pulley Settings are:

Min: 8000
Max: 24000
Ratio: 1

So the bottom voltage is perfect (within 1 rpm), but the top is way off.

Any help is appreciated.

Chris Swiger
« Last Edit: March 21, 2013, 04:46:39 PM by swaggs21 »
Re: Incorrect PWM Signal for Spindle
« Reply #1 on: March 23, 2013, 11:29:08 AM »
Hi Chris,
I assume that you have  measured both voltages with the VFD wired to the PMDX-107.

If so,then first test if your Linearity.dat file is corrupted. You can rename it or delete it.
A new Linearity.dat file will be created when you open Mach3 next time.
This file contains a linear " compensation "  curve.

You will find the file in YOUR PROFILE macros  folder. Take care you are in the right PROFILE if you have more then one.


Re: Incorrect PWM Signal for Spindle
« Reply #2 on: March 25, 2013, 08:29:18 AM »
Thanks for the info Alex, I will try at lunch time and see what I get.

Yes, I have tested the VFD with just the PMDX, and it is a solid 10VDC at the 24000 mark.

Will post back on the results.
Re: Incorrect PWM Signal for Spindle
« Reply #3 on: March 25, 2013, 05:04:10 PM »
Was able to spend some time with this a couple of minutes ago now that the power is back on.

I deleted the linearity.dat file, which did not fix the issue. So I started messing around with speeds and noticed that when I set the speed to 8000 in Mach, none of the Spindle Speed override buttons would work until I hit 170%, and it went up in very small increments after that. Obviously not what I was expecting.

So I shut the spindle off, went into Spindle Pulley Setup, changed the min speed from 8000 to 0, and everything worked as expected (within 100 rpm or so).

Thanks again for the help.