VFD Spindle control 0 to 10V (not -10 to +10V)

[NosmoKing]

NosmoKing, I'm using outputs 4 and 5 for reverse and forward control of the VFD, as you say.  I enabled them in the "Relay Control" box of the Ports & Pins dialog.  But, what do you mean by using the Jog+.

Mike

Of course I just realized that the Galil JG works if using either a servo motor or an encoder on the VFD spindle motor or the spindle shaft, the JG command followed by the slew speed will automatically output the voltage required for the slew speed commanded.
The down side is though with a VFD with +10v only you would need the bridge to obtain reverse, but at least the drop would automatically be compensated by the Galil reading the slew speed feedback via the encoder.
On a Lathe, Constant Surface Feed CSF should be possible with this set up also.
 N.

[Lohmeyer]

Yes, good point.  My spindle doesn't have an encoder, but I'm hoping to add one eventually for rigid tapping. 

With an encoder and the JG command, to make the Galil driver work without a diode on the output, it would have to change the encoder polarity using the MT command (MT 1 for forward, MT -1 for reverse polarity). 

Kenny, I assume the Galil driver use JG commands for spindles with an encoder, right?  If so, then in your update you sent me, we would have to add MT commands to the Custom Notify messages and M3/M4 macros as well for people with encoders.  But, your updated driver as is will still handle it.

I should mention, I don't like the diode because it creates a voltage drop which can skew the actual spindle speed (make it non-linear).  I know, maybe it's splitting hairs.  It depends on the current through the diode.  My VFD speed input is about 30K ohms, so at 10V, that's 0.33 mA at 10V.  A common diode will only drop about 0.1V at 0.33mA, so that's fine.  But VFD's with a lower input impedance (e.g. 5K or less will cause a 0.2V to 0.5V drop through the diode), and the voltage drop through the diode starts to become an issue for linearity (spindle speed will not be linear with respect to commanded voltage). 

But, using JG commands and an encoder on the spindle, this doesn't matter.  The Galil card will adjust the voltage to maintain the speed based on the encoder feedback.  That's useful. 

Mike

[kcrouch]

Mike,
That's correct, when an encoder is fitted we use JG to set the spindle speed. There are so many possibilities for spindle control that I like using the macros and custom notifies to get systems working well as changes are then much easier to implement for a particular situation. I am very afraid of breaking something that is working for a user unintentionally. In this case, I am going to add a checkbox for 0 - 10V and +/- 10V selection and use the custom macros and custom notifies to get it working for your particular installation. When verified, we will update the plugin and manual so that others can benefit from these changes.
Kenny

[TOTALLYRC]

Nice to see that you will be keeping the +-10v for the spindle because if you are running a servo drive on the spindle it won't work any other way.

Mike

[Dr_Mark_Vaughan]

It's now Aug 20111. Can I ask what state the spindle plugin is in.
For a simple spindle typical mach user with VFD running a 0 to 10V control without feedback, whats teh setup requirement?
Do we need to put an SM link on the Galil card?
I see no box to select -10V to +10V or 0 to +10V in the plugin configure screen.

Thanks Mark

[kcrouch]

Mark, I know that I have been working on this for a long time, but you've jumped us by 18.100 years! I can send you a copy of the new plugin as soon as I get back to my shop. Steve and Brian have been updating Mach and there will be changes needed to the plugin so I have been holding off of the later releases.
The one that I will send has the checkbox for 0-10 volt, but will need some changes made to the M3, M4 and M5 macros in order to set up any needed outputs to control direction. I can help out with those.
Cheers,
Kenny

[Dr_Mark_Vaughan]

Thanks Kenny
No immediate rush, I'm not quite there with it's install yet, just trying to cover possible problem areas before the conversion point of no return and avoid too much down time.  Thanks for the offer of help. I just need to get a 0 to 10V signal for VFD with M3 and M4 relays the same as many mach users operate. Actually just forward M3/M5 on/off spindle motion will do for now.
I did even wonder whether for spindle use, and to save some valuable outputs, whether the Galil was better confgured if possible to use the step/direction signal for spindle direction, and the enable signal to start the spindle. Easy enough then to wire the enable signal steered via a step direction relay to the CW/CCW inputs on a VFD. Not that I've read enough of the Galil stuff to know if that's viable, or viable to mach.

Regards Mark

[kcrouch]

Dr. Mark. I would advise against the step direction using the Galil as I don't think that it is provided for yet. If you use output 3 for forward and output 4 for reverse, You would simply turn output 3 on with the M3 macro and turn both output 3 & 4 off with the M5 macro. Likewise set the m4 macro to turn output 4 on to reverse your drive.
Kenny

[Dr_Mark_Vaughan]

Yep that's OK and what I had planned to do, was just wondering if we could be crafty and save some standard IO, perhaps an idea for future. Not important though I have enough IO.
Thanks Mark

[ionsignal]

Hello Kenny,

I have a dmc-1830 that I am in the process of installing for a Bridgeport retrofit with servos.  Can we use outputs to generate pwm signal for 0-10v converter like we do with the parallel port?  That would be great since this board has only 3 axis.

Mark