Re: following error question

[Dam <damg-at-1st.net>]

  Ray Henry wrote:

>
>I can understand why you want to make input_scale large.  It will 
>integrate to a voltage better but with any EMC stepper module you quickly 
>run up against the max pulse rate that your PC can spit out.  I'm certain 
>that I don't understand the relationship but it seems to me that In this 
>case, a max_velocity of four units per second and 40K pulses per unit 
>means that your PC will need to spit out 160KHz for a rapid. 
>
>Ray
>
Ray

The input scale of 40k is the encoder counts per unit,  2000 cpr * 4 
(quadrature) = 8000 ppr for 1:1 drive of a 5 TPI screw that = 40k per 
unit.  Output scale =10k step pulses per unit = 0.0001 resolution.  with 
the 2000 cpr encoder and input scale set to 10k per unit 1/4 revolution 
of the encoder produces enough encoder counts for EMC to display a move 
of 0.2000" which should require 1 full revolution. Output scale setting 
has no effect at all on encoder counts.  On my computer the max pulse 
rate is -at-30kHz,  at 10k pulses per inch moves of 180 IPM should be no 
problem.  Since there is no direct connection between output pulses and 
encoder counts EMC had no complaints with 240 IPM moves. The growling or 
grinding sound that I mentioned is caused by EMC throwing in some 
reverse direction pulses in an attempt to slow the motor down.  I'm 
reasonably sure that the inherent braking of a regenerative drive and 
the addition of tach feedback will make an awesome setup. Tach feedback 
alone would probably be enough but I have to try the regen drive just 
for kicks.

Everything between the parallel port and the motor is my own design. 
 Electronic systems do break down.  If I design and build it then I'll 
be able to repair or replace it at minimal cost when it does.  I'm a 
tool maker,  building things and making them work is what I do.  If you 
wonder why go to all this trouble when drives are available at 
reasonable prices,  well, because I can.

Dale