On Tue, 19 Apr 2022, gene heskett wrote:
Date: Tue, 19 Apr 2022 16:00:39 -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 12:46:20 EDT Peter C. Wallace wrote:
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
Ouch. That is going to need a power transistor on a heat sink to pull
that down to 4 volts. Thats around 15 mils. And a 1 Watt R.
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'll have to check that. I thought it was. Did, According to my ohmmeter,
it is a common ground.
I did get the flood button to appear in the axis gui, which is what I
will use to enable 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:
Or as I found, enable the device in the loadrt line and read the cards
signon output as you exec linuxcnc -l.
However, pwmgen.00.'s outputs do show up on the DIR4+- and
STEP4+-. terminals of the 7i76. But see 5i25man.pdf for data about it.
sudo mesaflash --device 5i25 --dbname1 7i76 --readhmid
(this needs mesaflash 3.4.2)
Not available for buster, it has 3.4.0-rc1 or similar.
You can get the latest here:
https://github.com/LinuxCNC/mesaflash
(scroll to bottom of page for build instructions)
Thank you Andy.
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
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