Re: Steppers or servos

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Steve Carlisle wrote:

>  Jon, what is this fixed upper step rate, that limits EMC's
> use. You did say that did you not.

It is not some specific, software defined value.  It is a combination
of things, mostly CPU speed, and maybe somewhat affected by
motherboard I/O details.  The freqmot task runs at a high
interrupt rate, generally somewhere about 10 KHz.  At 10
KHz, you can't get more than 5 K steps / sec.  If your CPU
will handle 20 KHz execution of freqmot, then you can get
10 K steps/sec.  One problem with this is the jump from
5K to 10 K would cause most steppers to stall.

A really fast (over 300 MHz) Pentium can probably go
faster than these numbers.

Jon