On Tue, 19 Apr 2022, gene heskett wrote:
Date: Tue, 19 Apr 2022 12:24:26 -0400
From: gene heskett <ghesk...@shentel.net>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] nother Q for Peter
On Tuesday, 19 April 2022 07:59:12 EDT andy pugh wrote:
On Tue, 19 Apr 2022 at 03:51, gene heskett <ghesk...@shentel.net>
wrote:
> So by default. a bit is .142578125 volts. Hummm. Seems odd. I would
> have expected $00 to $FF as output.
It does on the FPGA and the interface, but the driver converts to
floating point for convenience and then the default scaling is to
volts.
Can I access it raw as the hex value? volts doesn't really represent what
I need to work with. Although I assume the fp in volts does increment by
the value of 1 bit change, so that can be worked around.
You can scale as you wish with the scalemax parameter
How would I go about determining the resistor value to feed that input
from nominally 42.3 volts to just bring it to full scale? My additional
connections would "sink" it from there.
You would need about 3K to get 36V into the 20K input impedance with a 42V
source
I have a small voltage applied to that input, but a halmeter is only
reading a flicker of random noise at about 1 second intervals, zero the
rest of the time. Thats likely a clue I'm doing something wrong, but
what?
Is the input relative to field power ground? (the field I/O section
section is galvanically isolated from the 5V parts of the 7I76)
I did get the flood button to appear in the axis gui, which is what I
will use to anable the mister air seperately from the mister pump, and
will interlock the pump so air has to be flowing before the pump can be
started. 'Twould be nice if I could relabel that radio button from flood
to air, can it be?
I did just find the pwmgen's pins, which despite the fact that they steal
the 7i76's stepgen-4 pins, are addressed in the 5i25 as pwmgen.00.etc. No
mention of that in the 7i76 docs I assume because the pwmgens are
actually in the 5i25. Is pwmgen.01 then the same pins on the 5i25's p2?
You can use mesaflash to determine the 7I76 pins:
sudo mesaflash --device 5i25 --dbname1 7i76 --readhmid
(this needs mesaflash 3.4.2)
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, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Peter Wallace
Mesa Electronics
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