Re: Fwd: pulse train

[Ray Henry <rehenry-at-up.net>]

Scott

I don't believe that there is a chart that lists these things.  I'm not 
certain that there could be a single max value for all 667's regardless 
of configuration of the box it's in.

What I do is start out with a period value that is rather large.  The 
emc.ini gives some hints as follows.

; Base task period, in seconds
; Typical settings would be around :-
; 0.000015 for an 800MHz CPU
; 0.000040 for a 300Mhz CPU
; Don't use this if steppermod is being loaded.
PERIOD =                0.000032

I set [TRAJ] for the velocity that I want. 

DEFAULT_VELOCITY =      0.0167
MAX_VELOCITY =          1.2

Then set each axis MAX_VELOCITY a bit less than the max setting above.  
Then compute the number of pulses per unit and set the 

INPUT_SCALE =                   1000    0
OUTPUT_SCALE = 1000.000 0.000

to that same value.  

Now I start up the EMC and once the tkemc gui is up, move the mouse 
around in circles and watch the delay between updates of the mouse 
pointer.  If the pointer keeps up and is smooth, lower the period value a 
bit.  Repeat this process until you get noticable lag but you are 
satisfied that you can control the machine with the mouse if you need to.

If you get period smaller than your computer can handle you will see very 
long delays in the startup.  If you get max velocity higher than your 
period and processor can handle, you will get following errors on long 
commanded moves.

Hope this helps.

Ray
 
On Sunday 15 December 2002 04:16 pm, Scot wrote:
> ----------  Forwarded Message  ----------
>
> Subject: pulse train
> Date: Wed, 11 Dec 2002 09:26:39 -0800
> From: Scot Rogers <scotr-at-bogwell.com>
> To: emc-at-nist.gov
>
> Hi all,
>
> I'm getting ready to put my table motors and emc together and was
> curious about the pulse per second capabilities of emc with a Pentium
> III 667mhz or higher.  Is there any info avialable on my question?  I'm
> planning on using steppers in freqmod.  Unless there's things I should
> know that would push me other directions.
>
> Thanks guys,
>
> Scot
>
> -------------------------------------------------------