Re: following error question

[Jon Elson <elson-at-pico-systems.com>]

Richard Everett wrote:

> Hi again, In anticipation of getting the pulse multiplier for my Gecko
> drive, I installed BDI-EMC on a 1.4 ghz athlon thunderbird machine.  I
> then setup the emc.ini file with steppermod.o and input scale and
> output scale set to 5000.  I set the max velocity to 10,

10?  Remember, that is in user units per second.  If your user units are
inches, that is 600 IPM, which is
a bit fast for the larger machines.  Perhaps the Fanuc control could
deliver the power to do this.

and ran EMC.  Much better performance as far as the slugishness of the
interface.  When I tried to manually jog the motor 1 inch, I got a
following error after it had moved part way.  Are there any other
variables using steppermod that I should try? You should start with the
jog velocity at a low rate, and move up in steps to find out what is
happening.
You should also learn how to make the logging / graphing function work
(it is quite easy, just a few
mouse clicks, but you have to install gnuplot to see the graphs).  Then
you can find out why it is
getting the following error.  But, most likely, it still can't put out
step pulses fast enough.  The theoretical
limit would be around 500,000 steps a second, but the port is not the
bottleneck.  What is your
CYCLE_TIME in the axis sections?  If it is still at .001 second, you can
only get 500 (or maybe
1000) steps/second, I think.  If you command a move faster than that,
then the commanded
position will get ahead of the actual position, and a following error
will occur.

Jon