Re: Runaway z axis with steppers

[Paul <paul.corner-at-tesco.net>]

Hi Ray
The first thing to spring to mind is INPUT_SCALE and OUTPUT_SCALE are both 
negative numbers. Running the ini file with the current CVS sources on an 
rtai build, I too get the odd behaviour that you report. I have observed 
similar run aways when messing around with four axis configurations - Often 
with much more aggressive results.

After changing the INPUT_SCALE and OUTPUT_SCALE parameters (try 5 !),
I can get a repeatable result after every move. Increasing CYCLE_TIME to 
0.0015 improves the situation somewhat....
Suggestion - Increase CYCLE_TIME to 0.0015 - 0.0025 as SCALE approaches 10.
(I wonder if this is the answer for the fourth axis ??)

Regards, Paul.


On Saturday 07 Sep 2002 5:26 pm, Ray Henry wrote:

> Here is what I did to exhibit the problem.  
>
> Startup using timsfreq.ini.  (attached)
> Start the machine and home out.
> Start scripts->IO_Exercise to view parport 0x378. (default)
> Issue a couple of quick jogs in Z
>
> Once the problem shows up with the IO_Exercise display and I press estop,
> the step pin seems to latch but the displayed position runs wild.