On Fri, 19 Jul 2024, Todd Zuercher wrote:
Date: Fri, 19 Jul 2024 12:11:53 +0000
From: Todd Zuercher <to...@pgrahamdunn.com>
To: Peter Wallace <p...@mesanet.com>,
Todd Zuercher via Emc-users <emc-users@lists.sourceforge.net>
Subject: RE: [Emc-users] 5v Encoder Power?
Would it make a difference which card I have my 7i84 connected to? I currently
have it connected to the 7i85s. Would moving it over to the 7i88 be better?
Not much, the 7I84 only draws about 30 mA from the daughtercard 5V
Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street
Dalton, Ohio 44618
Phone: (330)828-2105ext. 2031
-----Original Message-----
From: Peter Wallace <p...@mesanet.com>
Sent: Wednesday, July 17, 2024 3:00 PM
To: Todd Zuercher via Emc-users <emc-users@lists.sourceforge.net>
Cc: Todd Zuercher <to...@pgrahamdunn.com>
Subject: Re: [Emc-users] 5v Encoder Power?
[EXTERNAL EMAIL] Be sure links are safe.
On Wed, 17 Jul 2024, Todd Zuercher via Emc-users wrote:
Date: Wed, 17 Jul 2024 16:59:54 +0000
From: Todd Zuercher via Emc-users <emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
Cc: Todd Zuercher <to...@pgrahamdunn.com>
Subject: [Emc-users] 5v Encoder Power?
Working on my 8 head machine refitting.
The machine had been previously configured using a Mesa 5i25+7i85s
doing closed loop step/dir control with encoder feedback of 3 servos(xyz).
(Other miscellaneous gpio was handled on an ISA card.) Power for the
Mesa 7i85s was through the cable via the 5i25.
With the update, the ISA card was replaced by a Mesa 7i84, and 7
additional step/dir outputs added using a Mesa 7i88. The new machine
configuration is using 2 of the old servos to control the either end
of the Y gantry (previously only 1 servo), and 8 closed loop steppers
have been added for each of 8 Z spindles.
It appears that adding and powering the 7i88 from the 5i25 has put too
much load on the 5v supply from the 5i25. Now, when the servo drives
are not powered I am having trouble with the encoder feedback running
away. I don't think this was a problem previously. When the drives
are powered they add to the 5v that supplies the encoders and the feedback is
steady.
Thats unexpected since the 7I88 should draw only a few 100 ma when fully
loaded. Are you sure the 5I25 and 7I88 cable power jumpers match?
My 1st question is how large of a 5v supply should I add to power the
7i85s and the encoder feedback? Should I power both the 7i88 and
7i85s using this supply or keep one powered from the 5i25? Would
powering from a USB port be sufficient?
The 7I85S draws about 250 mA by itself, any encoder power needs to be added to
this
Next question while I setting up and trying to tune the gantry servos,
I found that I was having trouble with the position feedback from the
Mesa stepgen getting out of sync with the feedback from the encoders
if the drives were ever disabled. Then when I am trying to run closed
loop using the encoder feedback, if the drives are disabled, I have
trouble with joint following errors when re-enabling them. Any suggestions for
this problem?
I believe the problem is the gantry is going out of alignment when
shut down and there needs to be some provision for resyncing them when
they are re-enabled. But I'm not sure what steps need to be taken to do that.
Rehoming might be an option (but not what I'd prefer), but I can't
even turn the machine back on (F3) without closing and restarting Linuxcnc.
If you are running with encoder feedback, the stepgen position should not be
used (the stepgens would be run in velocity mode and only encoder feedback
used)
Todd Zuercher
P. Graham Dunn
Inc.<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2F
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630 Henry Street
Dalton, Ohio 44618
Phone: (330)828-2105ext. 2031
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Peter Wallace
Mesa Electronics
Peter Wallace
Mesa Electronics
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