[LeRa]

Thanks for all the replies, they have been really helpfull.

I got hold of some more detaild schematics of a slightly different (i think newer) type of velocity unit for Fanuc 6M. These helped me understand more of the meaning of the potentio-meters.

The biggest problem was the TSA-signal, which wasn't what the velocity-unit was used to (I use the USdigital unit for the tacho-signal that HillBilly sugested). But setting some (DIP-)switches on the velocity-unit cured that problem. The tacho had too much influence.
Furthermore some potmeters for the firing-circuit weren't set right. And tweaking some minor things helped smoothning the ride.

Now I go for the next step; closing the position-loop.
I'll let you know if that works out.

[LeRa]

Using a motion controller from National Instruments (the 735x-series), I closed the position-loop.

It took some time to figure out all the possible directions (for limit switches, velocity-feedback, position-feedback and more) but now it works fine. Only some minor tweaking has to take place for a completely smooth movement.

Thanks again for all the replies.

[HillBilly]

LeRa,

This is interesting, A couple of questions.
Are you inputing step and direction commands for position?
Are you only dealing with P gain in the position controller?

Darek

[LeRa]

Darek,

No, i'm dealing with a servo (not a stepper-motor) so my input is 'number of counts to move'. The feedback to the controller is the encoder of the motor, maybe in a later stadium I'll incorporate another encoder for position-feedback.

The controller is a full PID-controller, but i'm only using the P- and D-gains.

LeRa

[precourt]

So how everithing turned out?

I will use a GAlil motion card for controling the same servo drive and the same motors.

I will also use the US Digital Etach2 for TSA.


Any comments would be welcomed.

[LeRa]

Precourt,

Now everything is operating. I had to compromise the max speed and acceleration (and of course deceleration) for a more smooth run, but that's all due to the wear of the complete machine.
I did use a Heidenhain position-feedback for both axes for the controller instead of the encoders of the motors, also because of the small wear of the machine itself.
Closing the velocity-loop with the drive was not simple but after some fiddling with the potentiometers I got a fairly smooth movement.
The PID or better PIV values of the controller took also some time to optimize. I do think you will not have any troubles doing the same with the Galil-controller. (I do have some experience with them also)
The US Digital Etach2's (connected to the encoders of the motor's) were set to 63kHz, which is a value you can use if you have the same motor's (with the same max rpm's).

Good luck,
LeRa

[precourt]

My motor does vibrate without load If I let it vibrate a bit too long I kept blowing fuse on one phase.

I know that this drive was woking very well on the Fanuc systems.


This appen even if I set the gain very low.

You say that you adjusted the firing timing adjust pot could you explain more what you ve done.

Also any insight could be good.


Regard

Erik

[precourt]

Thanks for all the replies, they have been really helpfull.

I got hold of some more detaild schematics of a slightly different (i think newer) type of velocity unit for Fanuc 6M. These helped me understand more of the meaning of the potentio-meters.

The biggest problem was the TSA-signal, which wasn't what the velocity-unit was used to (I use the USdigital unit for the tacho-signal that HillBilly sugested). But setting some (DIP-)switches on the velocity-unit cured that problem. The tacho had too much influence.
Furthermore some potmeters for the firing-circuit weren't set right. And tweaking some minor things helped smoothning the ride.

Now I go for the next step; closing the position-loop.
I'll let you know if that works out.

I am interested in some more explanation on this.

I do use the axact same setup US digital and Fanuc 6m 20 series motor and drive.

SO far the motor stand still but do vibrate.
Any adjustement didnt make nothing better.

If anybody have some way to help.

Thanks

[Al_The_Man]

I am interested in some more explanation on this.
I do use the axact same setup US digital and Fanuc 6m 20 series motor and drive.
SO far the motor stand still but do vibrate.
Any adjustement didnt make nothing better.

Is this just the velocity loop (the controller not connected)?
This should be stable first, before closing the controller/position loop.
Al.

[precourt]

Yes the controler disconnected with 0Volts on VCMD and US digital tach signal on TSA.


Erik

[LeRa]

Precourt,

If you haven't already turned the potmeters concerning the firing if the IGBT's on the drive's, then it is best to leave them where they are, because these are not different using the original Fanuc-controller. If you have, then you should use an oscillosope and try to make the firing-length for every phase the same. That is zero with 0 volt applied and same lengths when a low constant voltage (be carefull not to run into any limits) applied. Right now I do not know which exact potmeters, but they are designated A,B and C I think.

Something else you can try is turning down the dither potmeter.

Good luck,

LeRa

[maquiza]

LeRa,

Hello, Do you think that you can use a 7V/1000 rpm tachometer, instead of the 6V/1000 rpm, adjusting the RV1 gain and RV2 offset on the velocity drive?
Thanks,

Jorge

[pateltechnomati]

hi
i personally want to thank you for your details.
i have one question for fanuc 5,6,7,9 etc..
1-if motor dont have tacho gen. in fanuc dc servo and if all velocity controller works fine and i want to change cnc controller like fagor ..siemens...which can interface analog drives and ...
2-can i use same motherboard of fanuc to generate tacho for all axis drive and if i supply analog direct to cav connetor and rest of signal to cav ?
3-how fanuc mother board generate tacho signal?(i checked that there are three big ic named fanuc pos 9748 which is for x,y,z axis in 6m mother board and pin number 14 and 15 is encoder input and 12 ,13 is input signal for pc06 pin number 3 and 5 i found this from your diagram)
4-can i generate tacho without any card on mother board?
5-which type of signal accept by pc06 on its pin number 3 and 5
6-i found that big ic fanuc pos 9748 is generate output at pin 12 and 13 when cnc works fine but if cnc in emergency state it will not generate tacho signal if we rotate motor with hand .

can you give me detailed idea how i can generate tacho using fanuc mother board

one more question

can i use this encoder signal for feedback to other controller if tacho works with your suggetion...

thanks in advance

[jorber]

So how everithing turned out?

I will use a GAlil motion card for controling the same servo drive and the same motors.

I will also use the US Digital Etach2 for TSA.


Any comments would be welcomed.

Hello I need an Etach2 now in 2020 they are not sold anyone knows about a replacement or something similar