On Sat, 26 Jun 2021, Gene Heskett wrote:
Date: Sat, 26 Jun 2021 12:51:03 -0400
From: Gene Heskett <ghesk...@shentel.net>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] About the 7i76E and possible DB25 expansion cards
On Saturday 26 June 2021 12:17:15 Feral Engineer wrote:
Hey John,
I guess i should've explained better, I was half awake when I asked
that. I'm running dmm servos on my mill, which are currently driven on
a 7i76e with step/dir and are only semi closed loop (closed loop from
the motor to the drive, but not to LinuxCNC). I'm Curious if it's
possible to use the external encoder feedback from the dyn4 to
LinuxCNC to create a full closed loop arrangement using that encoder
and step/dir or do the servos have to be controlled via analog signal
and pid tuning to get the encoder feedback to be closed loop?
Also, I'm looking for the secret sauce to get full closed loop from my
vfd to LinuxCNC if anyone has pointers on that. I have encoder
feedback to LinuxCNC, but i feel like I'm missing a key element to get
the pid working properly. Most of the adjustments I've made to pid
never result in LinuxCNC compensating for the error (i.e. G97 S200 =
S210 actual with p =0, changing P results in a runaway in most cases).
I'm wondering what the magic net command might be to get everything
working so I could thread on my lathe.
Phil T.
The Feral Engineer
Exchange the A & B signals from the encoder to LCNC, either in the .hal
file, or physically, it sounds as if the LCNC PID thinks its running
backwards. Check for sure by watching the encoder output with a
halmeter, it should be counting up when the motor is turning fwd, and
vice-versa.
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>
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Also the hal connections or encoder scaling of the PID feedback signal may be
wrong. Check the PID feedback value, it should be close to the commanded value.
Peter Wallace
Mesa Electronics
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