PWM spindle speed, feedback loop control

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PWM spindle speed, feedback loop control

Postby DavoH » Sat Dec 16, 2017 10:46 am

I have been using UCCNC for a few years but have had a break from the machine shop for a few months and have now just installed version 1.2047.
I am using UCCNC with a USB UC300/M44 combination and a PWM spindle controller with a single index pulse for each spindle revolution.
My spindle speed control works very well and accurately using Mach3 (parallel port) but not in any version of UCCNC I have tried (and I have a tried a LOT).

In the past I have sent many e-mails to support about not being able to get UCCNC to control the spindle as I expected it should.
I spent countless hours trying to get it to work as I expected (like it does in Mach3). I did get e-mails from support suggesting various things but they were no help.
During my last attempt at troubleshooting, some months back, I discovered that UCCNC does not and cannot control the spindle speed using a feedback signal from the index pulse. I was not impressed!

On reading the user manual (V1.0042) for UCCNC V1.2047 I see in section 3.2 Spindle setup it says..."The spindle PID controller function is is only available with our ethernet motion controllers
(UC400ETH and UC300ETH), this functionality is not available with our USB controllers (UC100 and UC300)."

It also says... "For the spindle PID control to work the followings are required:
- The spindle speed has to be controllable with the output PWM or analog output signal.
- An incremental encoder with A and B channels has to be connected and measure the spindle speed
and the encoder resolution has to be configured.
(Note: Single Index channel feedback is currently not supported, only an incremental encoder can
be used.)"

Well, thanks for finally confirming my suspicions.
Why was I never told that UCCNC did not support full spindle control using USB? I am not happy, having wasted hours and hours on trying to get it to work!

So, WHEN is it going to be implemented for USB using a single index pulse??
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Re: PWM spindle speed, feedback loop control

Postby cncdrive » Sat Dec 16, 2017 2:06 pm

Yes, that is correct, the USB controllers do not support closed loop spindle speed control.
The Ethernet controllers do, but it was implemented only maybe a half year ago.

There is no spindle PID control setting in the USB controller settings so I don't understand why did you think it can control the spindle speed?
I mean I don't understand what made you think that you can PID control the spindle with the USB controller when there is no such setting in the software for that controller?
What you could even try when there is not even such setting in the software?
Also the manual never said that spindle PID control is available for the USB controllers, the spindle PID control got into the manual when it was implemented into the ethernet controllers and a note was also added that it is a function that is supported only in the ethernet controllers.

The USB controllers will likely never support spindle PID control, because there is no enough room in the microcontroller memory and no enough available processor time in the microcontroller to supprot this new feature. The ethernet controllers are newer models with far more powerful micrcontrollers is why they can support this function.
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