On Wed, 21 Aug 2019, John Dammeyer wrote:
Date: Wed, 21 Aug 2019 17:16:50 -0700
From: John Dammeyer <[email protected]>
Reply-To: "Enhanced Machine Controller (EMC)"
<[email protected]>
To: "'Enhanced Machine Controller (EMC)'" <[email protected]>
Subject: Re: [Emc-users] MESA 7i92H Saga
In case anyone is interested:
%
G0 X0.000
G0 X0.001
%
Starting from position X=0.001" my Tek MSO3034 scope shows the move back to
zero and then to 0.001. The direction line set in the + direction rises to
the - direction and moves to 0.000. Then immediately changes to the +
direction and another 15 step pulses to move back to 0.001. And then the
direction line toggles 3 times.
And although DIRSETUP in the ini file is set to 1000 nS the actual time from
rising dir pin to first step pulse in this example was 2.89mS. The change in
direction to first step to go back to 0.001" was 3.23mS.
Its expected that you will not step instantly when you move because you starting
somewhere between steps (and the control loop has a resolution of 1/65536's of a
step) plus the initial velocity is very low
John
It doesn't appear to do any harm since the step lines are stable. But it's odd
and very repeatable in either direction. The direction signal always returns
to + direction regardless of the jog direction. The attached screen shot show
a 0.001" move in the negative direction with exactly 15 steps which matches
motor encoder and 3:1 pulley and 5 TPI lead screw.
I'll temporarily remove the limit switches, backlash and run a short G-Code
program that moves 0.001 and then -0.001" and capture the direction signal.
Very curious.
The other reason fo the assymetry of the direction behavior at 0 is the use of
signed rather than sign-magnitude numbers (so 0 velocity has a positive sign)
Peter Wallace
Mesa Electronics
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
