>>You might also add something where when the output goes below a certain level it turns off the VFD and possibly apply the brake.

--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
>
>
> Hi Dean,
>
> I encourage you to try controlling it like a Servo.  The main issue is that the VFD doesn't accept +/-10V but rather 0-10V with switches for on/off/direction.  You would need a small KFLOP C program to convert the +/- 2047 Servo Output to a sign and magnitude (absolute value) where the magnitude would go to the DAC and the sign would control the direction to the VFD.  You might also add something where when the output goes below a certain level it turns off the VFD and possibly apply the brake. 
>
> Regards
> TK
>
>
> ________________________________
> From: deanw1a <deanwyant@...>
> To: DynoMotion@yahoogroups.com
> Sent: Tuesday, July 16, 2013 8:02 AM
> Subject: [DynoMotion] Re: KAnalog with VFD/Encoder - speed/position control - like a servo?
>
>
>
>  
>
>
> I thought the question might be fairly generic easy question, so I did not post a link to the manual.
> I was hoping that most VFDs with sensor-less vector control (or closed loop vector) might be able to run a milling spindle (or lathe spindle) as a KMotion axis using PID for the analog input frequency. Thus, being able to maintain constant speed under varying torque, stop at a tool change position, etc.
> I was just thinking of accurate spindle speed control under varying load, ridgid tapping, stopping at a usable orientaton for tool change, and maybe syncing to anoter axis for some purpose.
> Perhaps I should have left out "like a servo" :)
>
> Is the "KMotion axis / PID" approach incorrect?
>
> One link to a full manual is here:
> http://www.omron-ap.com/product_info/3G3MX2/index.asp
> where it states:
> "High starting torque
> With the sensorless vector control and auto-tuning functions, this Unit ensures high starting torque of 200% at 0.5 Hz."
> And from an on-line brochure:
> "The MX2 Inverter delivers 200% starting torque near stand-still (0.5 Hz) and can operate in torque control in open loop mode."
>
> I thought it might be a plus that the MX2 drive can take a analog torque reference instead of a frequency reference. I do not know how I could use this feature without it being a KMotion axis. Of course, I do not "need" to use Torque Control.
>
> It can also perform simple position control (multiple programmed positions). That does not seem useful for a milling application. But, it does seem to indicate that the drive is capable of rough position control.
>
> In the quote from the other doc link you posted:
> >>if you need the motor to stop and hold the load position without the aid of a mechanical brake...
>
> The spindle has a brake and does not need the controller to hold position while stopped. Also, full torque is not needed at < 200 RPM.
>
> It would be awesome if DynoMotion products could make any VFD and AC Induction Motor combination perform like a Servo Drive and AC Servo Motor :) If they could, I figure I would have found more discussions about it.
>
> I just got excited when I saw that the MX2 drive had a Torque Control option...
>
> Thanks.
> Dean
>
> --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> >
> > Hi Dean,
> >
> > You did not include any specifications or links.  I Googled and found this:
> >
> > http://www.yumpu.com/en/document/view/4993081/mx2-users-manual-omron-europe
> >
> >
> > Which says this:
> >
> > Q. Can I use an inverter and AC induction motor in a positioning application?
> >
> > A. That depends on the required precision, and the slowest speed the mo-
> > tor must turn and still deliver torque. The MX2 inverter will deliver full
> > torque while turning the motor at 6Hz (180RPM). DO NOT use an inverter
> > if you need the motor to stop and hold the load position without the aid of
> > a mechanical brake (use a servo or stepper motion control system).
> >
> >
> > So I don't think it will work.
> >
> >
> > Regards
> > TK
> >
> >
> >
> > ________________________________
> > From: deanw1a <deanwyant@>
> > To: DynoMotion@yahoogroups.com
> > Sent: Monday, July 15, 2013 3:57 PM
> > Subject: [DynoMotion] KAnalog with VFD/Encoder - speed/position control - like a servo?
> >
> >
> >
> >  
> > I am retrofitting a Shizuoka AN-S Turret Knee mill that used a Bandit I controller (spare time project). I was going to use the existing reversible motor contactor with relays to control the spindle. But, now I have a OMRON MX2 VFD and I am drawing up connections etc. for.
> >
> > This VFD can take 0-10V for frequency (speed) or it can be configured as sensor-less vector control and take 0-10V Torque control.
> > It seems to me that if I can install an encoder on the spindle motor or, better yet, the spindle, I should be able to input that to KAnalog, setup the spindle motor as a "C" axis and use the PID settings the get position control of the spindle as a coordinated axis and jog it for speed as a non-coordinated axis... much like if it was a servo system.
> > Is that correct?
> >
> > The Shizuoka uses a spring loaded pulley/sheave on the motor (Reeves?) and a manually adjusted one on the spindle. It also has a manual High/Low gear system. So, it seems to me that an encoder on the motor would not do any good unless I disabled all of the manual controls. Is that correct?
> >
> > Or, could I set up two axis configs, keep the manual speed control set at one setting (max.. and never change it) and change configs according the to what the manual High/Low was set for?
> > The reason I would like to keep High/Low is that the the frequency would not need to be real low for tapping or real high for small carbide.
> >
> > I can probably get an encoder hooked up to the motor. But, I have no clue how I can get an encoder installed for the spindle. I will have to look closer at the High/Low gear section.. maybe there is room / a method to install it there. Does anyone have any suggestions on where / how an encoder can be installed on a motor / spindle like this?
> >
> > Thanks.
> >
>