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Author Topic: CNC4PC C11G Analog Output Spindle Control  (Read 15081 times)

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Re: CNC4PC C11G Analog Output Spindle Control
« Reply #10 on: December 01, 2009, 11:51:43 PM »
Thanks all for the help, it looks like I am going to need to mess with it a significant amount of time to get things up and running, that is the way these home-made machines go :-)

Pete, are you referring to the coolant pump wiring?  If so  one of the relays on the C11G should do the trick  per GrandMasterB, but note the rated contact current and voltage.  Is your coolant pump AC?  If so and you are using the relays for something else you can get solid state relays for switching AC loads that are reasonably cheap, and the input will operate off of the 5V from the bob and you can switch 110-240VAC depending on what relay you get.

Hope that helps,
Dustin
Re: CNC4PC C11G Analog Output Spindle Control
« Reply #11 on: December 02, 2009, 03:41:06 AM »
Hi i also use the C11g and am very happy with it.

One thing not mentioned so far is pulleys, yes pulleys

Unless you set at least one pulley and them use that pulley Mach will not be able to correctly work out the necessary figure to control speed

Having set the pulley up you then feed the C11g with 12v

Next adjust the setting to give 10v at max speed of the PULLEY

Then drop the speed by 50% the voltage should drop to 5v

Only when you have achieved this do you connect to the VFD

On my lathe which i am using a SS i had a devil of a time getting 10v i had to adjust the pulse width to do it to 8.5 if i remember correctly

I converted a redundant PC power supply to supply the required 5 & 12 volt for my control systems as they are very stable and easy to come by

If you do a google search for " CONVERT A PC POWER SUPPLY TO BENCH POWER SUPPLY" you should be able to find the article

HTH
Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: CNC4PC C11G Analog Output Spindle Control
« Reply #12 on: December 02, 2009, 11:58:56 PM »
Thanks for the comments all, I think it will work now after tons of messing around.  The problem was something with the VFD power supply not cooperating with the C11G, or just not working properly.  I tuned the output to be very linear with the 10V from the power supply, with in a few tens of mV, stable and nice.  But with the spindle on the voltage was all out of whack, generally ~1V higher than with the spindle on, but with varying wildly +/- 1V or so of where it was with the spindle off.  Both tests were done with the VFD powered on but just with it in the off state for one.  The funny thing was that the 10V was stable, at least with a digital volt meter.  I was afraid to hook the scope up to it to see if it was rippling but it looked solid because I don;t have a differential probe and am not sure what those lines are relative to earth.

I even measured the pulse widths and plotted the frequency output VS speed and everything looked fine.  Finally I just hooked up a 12 supply and all seems to be working now, although I have not thoroughly tested it yet, tomorrow...

Dustin

Offline ftec

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Re: CNC4PC C11G Analog Output Spindle Control
« Reply #13 on: January 02, 2010, 03:01:37 PM »
I'm using CNC4PC C11 rev. 9.3 and I just can't get it deliver more than 9.3V from the 0-10V analog output. I get the 9.3V at S20500 while the max is S24000. If I go over 20500 rpm the voltage will drop again to somewhere around 8.5V. My VFD does not deliver 12V so I'm using an external DC/DC converter which delivers 11.88V from the 5V supply, a 0.1% error I guess shouldn't make that much difference, or? Any ideas what to try next. (Unless - being sarcastic - the card rev # 9.3 means that you need to stick with 9.3) :) :(   

/Risto
Re: CNC4PC C11G Analog Output Spindle Control
« Reply #14 on: January 02, 2010, 06:16:48 PM »
I'm using CNC4PC C11 rev. 9.3 and I just can't get it deliver more than 9.3V from the 0-10V analog output. I get the 9.3V at S20500 while the max is S24000. If I go over 20500 rpm the voltage will drop again to somewhere around 8.5V. My VFD does not deliver 12V so I'm using an external DC/DC converter which delivers 11.88V from the 5V supply, a 0.1% error I guess shouldn't make that much difference, or? Any ideas what to try next. (Unless - being sarcastic - the card rev # 9.3 means that you need to stick with 9.3) :) :(   

/Risto

What voltage are you providing to it?  The spindle control will NOT be able to provide the full input voltage.  So, if you want 10V out, you'll have to provide it with 11-12V in.

Regards,
Ray L.
Regards,
Ray L.

Offline ftec

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Re: CNC4PC C11G Analog Output Spindle Control
« Reply #15 on: January 02, 2010, 06:22:18 PM »

What voltage are you providing to it?  The spindle control will NOT be able to provide the full input voltage.  So, if you want 10V out, you'll have to provide it with 11-12V in.

Regards,
Ray L.

11.88V as I said in the post. I'm now using an adjustable Mascot to get little over 12V and this seems to have some effect but it doesn't convince yet ... (edited).
« Last Edit: January 02, 2010, 07:19:11 PM by ftec »
Re: CNC4PC C11G Analog Output Spindle Control
« Reply #16 on: January 03, 2010, 01:54:56 PM »
ftec,

It sounds like maybe it is a setting in the spindle setup in mach 3 under the motor tuning tab.  I had to mess with the pulse width and rate etc to get what I wanted out of the thing.  It took quite a bit of messing around, but now it works well, my only complaint is that the speed takes a few seconds to stabilize, but it really does not matter, I am super happy with how it works now.

Dustin
Re: CNC4PC C11G Analog Output Spindle Control
« Reply #17 on: January 03, 2010, 02:04:27 PM »
One other thing I cannot figure out is the pulse width setting, can you not change the value independently?  I had to set it to 10us on the spindle to get the voltage high enough, but I would like to have the servo pulses be 5us.  Is there any way to do that?  Now it just changes all the values at the same time.

Dustin

Offline ftec

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Re: CNC4PC C11G Analog Output Spindle Control
« Reply #18 on: January 03, 2010, 04:01:38 PM »
It seems that I got the spindle analog voltage issue solved for the C11 card for my 24000 rpm spindle. I believe all the cnc4pc cards use the same concept for the voltage, C11G as well.

The answer for the linearity issue can be solved from the pulley setup. In my first attempt I set the pulley max rpm to my spindle max rpm 24000. This resulted a voltage of 9.3V @ S24000 and 7.5V a@ S12000.  You can get better linearity between S0 and Smax by adjusting the pulley max rpm over the true Smax rpm.

After many attempts I now have pulley max set to 27500 (ratio =1) and using the pot on the C11 card the voltage is adjusted to 10V@S24000 (i.e. my spindle max rpm). This resulted 5.04V@S12000 which certainly is pretty good and enough for my purposes. In the motor tuning I have (mm based) steps per unit 1000, Vel 2700, acc 500, step pulse width 2us dir pulse width 2us (btw. if you noticed, these pulse width values are shared with the servo axis why I have left those to be what I had them tuned for the servos.)

A very small capacitor across the analog GND and voltage could stabilize the analog control signal from drifting but I haven't tested that yet. A cheap way to shield the analog signal is to use a cable taken from say a RS232 D9 sub cable which usually are shielded cables. Only the other end of the shield should to be grounded to signal ground (otherwise currents can flow thru the shielding).

Regards,

/risto
« Last Edit: January 05, 2010, 01:36:39 AM by ftec »
Re: CNC4PC C11G Analog Output Spindle Control
« Reply #19 on: January 04, 2010, 09:23:13 PM »
One other thing I cannot figure out is the pulse width setting, can you not change the value independently?  I had to set it to 10us on the spindle to get the voltage high enough, but I would like to have the servo pulses be 5us.  Is there any way to do that?  Now it just changes all the values at the same time.

Dustin


The problem you have is that, the speed controller chip converts the pulses from the step pulse to an analog voltage via a charge pump. With a longer step pulse, more energy is put into the chargepump and a higher voltage results.

On by Step/Dir DigiSpeed, I have additional circuitry that ensures that the pulse length fed to the chargepump, is allways the same regardless of the Mach3 step pulse width. That way, you can set the step pulse width to match what your motor drives need rather that what the analog output voltage signal needs.

http://homanndesigns.com/store/index.php?main_page=product_info&cPath=1&products_id=39


Cheers,

Peter.
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com