[JiriK]

I'v built a cnc- mill with steppers. Since I have some Dunkermotoren brushless servo motors and even some power stages (pwm+dir in) for them I decided to try to upgrade my mill to servos.

I bought a Pluto-P card because of low cost and ready sample files in EMC.
I don't remember what version of Pluto I first had, but problem was this:
Motor would spin smooth only when input scale was set to 4000-6000 level. Correct value was 800.. With 800 motor rotation was somewhat noisy.
I tested several PID values but gave up..

So I installed new EMC (with that BDI install CD)
Now motor spins better with correct scale value but only in one direction. It doesn't spin at all to other direction!

Things tested so far:
set pwmdir of axis0 high (pwm+dir mode)
Swapped encoder-A and enc-B -> instan jog error.
Manually set Axis0 Dir- pin to high (and swapped encoder wires) -> Direction changed, but still only one way rotation.

Any ideas?
I'm new to this EMC and Linux- tweaking so it might be something simple..

[samco]

I showed this to the developer that developed the pluto firmware.. He did find a mistake. http://cia.vc/stats/project/emc/.message/5c17ff

I think they are going to try to release 2.2.4 this weekend so you could just update emc2 when that happens..

Otherwise you need to run compile and run pre-release branch
http://wiki.linuxcnc.org/cgi-bin/emc...06_from_source

using this incantation.
export CVS_RSH=ssh
cvs -z5 -d:ext:[email protected]:/cvs co -rv2_2_branch -demc2.2-branch emc2

[samco]

They did release 2.2.4 this weekend. You can go into the update manager and get the latest.

You can read about it here.
http://axis.unpythonic.net

pluto_servo: fix for pwm+direction mode

[JiriK]

Thanks, samco.
I updated emc - Now the motor spins both directions.

Rotation isn´t as smooth as I hoped.. It still makes kind of rattling sound as it goes.
Well, long way to go until this setup is moving axes of my mill but a bit closer now that it goes both directions.

[samco]

You need to tune the pid loop. (something that is hard to explain - you just have to do it.)

http://www.linuxcnc.org/docs/2.2/htm...id_theory.html
http://wiki.linuxcnc.org/cgi-bin/emc.../HAL_PID_Loops

emc has P,I,D,FF0,FF1 and FF2

There is an autotune pid - you could try. (the servos would have to be hooked to the machine and you would have to be up on hal)
http://www.linuxcnc.org/docs/html/ma.../at_pid.9.html

sam

[JiriK]

I have tested several PID parameters but no luck so far..
I´ll try that autotuning system.

Thanks again!