On Wed, 21 Aug 2019, John Dammeyer wrote:
Date: Wed, 21 Aug 2019 18:51:34 -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
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
Yeah, that last step pulse of course is at the end of the deceleration so
without doing he real math based on parameters and motion it's hard to say
specifically what the speed of the motor is as that last step is issued and
then when the motor is actually stopped. Wasn't complaining about the time
taken. Really just an observation.
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)
So that implies that every time it moves to a point where it's stopped the
system thinks it's going in a positive direction so then sets the direction to
that. Interesting. Nice to know. Doesn't explain the 3 pulses. Do you
think the parallel port stepper does this or is this unique to the 7i92H?
No sure if it has any hysteresis to prevent this or not
The 3 direction changes are probably related to tuning and the
the signed velocity
BTW, I now have the step rate for 3000 RPM coming out of P1 port. Just need
to convert that to RS422 since the motor driver is only rated to 200kHz with
TTL pulses.
Baby steps...
Peter Wallace
Mesa Electronics
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Peter Wallace
Mesa Electronics
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