Re: emc with camtronics more help please

Ben

With respect to the ini file the things that I'd be sure to do is set
accel. MAX_ACCELERATION = 5.0 or less

With 4000 steps per inch I'd also set some deadband. A full step will get
you 0.00025 so deadband ought to be a little more than half that. This
will stop the emc from driving your steppers between two steps if the
commanded value falls in the middle.

With freqmod, you will not get very high speed from it with your CPU but
you should get significantly smoother motion. With a P2 processor
underclocked to 150 and 64 Meg of memory I can run freqmod using these ini
settings.

PERIOD = 0.000035
DEFAULT_VELOCITY = 0.0167
MAX_VELOCITY = 0.501 (30 ipm)
DEFAULT_ACCELERATION = 5.0
MAX_ACCELERATION = 5.0
INPUT_SCALE = 4000 0
OUTPUT_SCALE = 4000 0.000

Period might go a little faster on my PC, 0.000031 or so. You you can
test this by starting up the emc and seeing how well the mouse pointer
follows mouse motion. Some jumps can be expected so set it to what is
tolerable for you. (Take account of Franks notion of extra memory here
also.) If your PC reboots or dies on startup, you have period set much to
small.

Get period where you want it and then test max velocity using following
error. Acceleration is the biggest contributor to following error. If
you get a following soon after starting an axis reduce this first.

Max velocity might also go a little higher. You can test by driving your
longest axis from one end to the other at g0. If you get a following
error along the way, max velocity is to fast.

If you do use freqmod, there is a granularity issue at high speeds. Jumps
between available frequencies can cause one motion loop to run at top
speed while the next motion loop runs at much lower speed. You will hear
this as an oscillation from the motor. A stethoscope, or metal rod
pressed to the motor and to your ear, may help. If you get violent
changes in speed during a constant velocity move or during a circle it can
cause missed steps. If you find such bothersome granularity you can slow
the speed or reduce the period.

HTH

Ray

>    From: "bgroover1" <bgroover@...>
> Subject: emc with camtronics more help please
>
> Sorry to keep asking question but emc is killing me.  I'm using
> stepermod and I can't seem to get emc to move the same amount every
> move.  Computer is a p150 pro.  I get it set up.  I know my x axis
> needs 4000 steps to go an inch.  I run emc.  I move .001 it
> moves .001.  I do it x times it works x times.  I do it once more and
> it may not move or it moves .003  It may move .1  three time in a row
> with no error and on the forth time drops anywhere between .001
> and .01
>
> I've tried tuning the ini file but it doesn't seem to help.  Can
> anyone tell me what variable in which section I should be looking
> at.  I've tuned emc.ini serveral times with all the docs I can find.
>
> Should I use feqmod instead?  Will it work with the camtroncs 5amp
> controllers?
>
> Thanks in advance for even more help.
>
> ben