On 3/8/24 15:28, Peter Wallace wrote:
On Fri, 8 Mar 2024, Todd Zuercher wrote:
Date: Fri, 8 Mar 2024 19:59:14 +0000
From: Todd Zuercher <to...@pgrahamdunn.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: [Emc-users] Mesa 7i84 Field IO?
Hello,
I am working at connecting a 7i84 IO card to a machine that I am
refitting a newer Linuxcnc PC to. The old PC used an ISA card for
IO. That will no longer be an option with a newer PC.
My questions, the servo drives used 5v TTL signals for IO signals
specifically the ready/fault output, and the enable input. How should
I interface these with the new 7i84 card (which is using 24v field
power)?
The ready/fault output seems simple enough. It is an "open collector
outputs without pull-up resistors, they are rated for switching
non-inductive loads up to 40V at a maximum of 100mA" (quote from the
drive's manual). So I simply need to add a 24v pullup for each of
those signals. The question is what size pullup resistor should I use?
The harder question for me is how to handle the 5v drive enables?
Would it be best just to connect them to via a relay? Or would there
be a better way?
Other Mesa cards in this system, a 5i25, 7i85S, and 7i88. Both
parallel port headers are used on the 5i25. The smart serial port on
the 7i85s is used to connect the 7i84. All of the step/dir outputs on
the 7i88 are being used. The only IO not being used are on the 7i84,
one encoder input and one step/dir output pair on the 7i85s.
Would it be ok to try to use one of the free the step or dir outputs
as the 5v enable signal for all 3 servo drives or is a relay on one of
the 7i84 outputs a better idea?
Todd Zuercher
P. Graham Dunn Inc.<http://www.pgrahamdunn.com/index.php>
630 Henry Street
Dalton, Ohio 44618
Phone: (330)828-2105ext. 2031
Don't forget the enable input on all the drivers I have bought are
defaulted to on if not hooked up. That is OK on my stuff as the power is
totally shut down if F2 isn't enabled. Each machine has a box of 60 amp
SSR's controlled by a haL hookup. F2 off, whole machine is totally cold.
I even have the 4 foot, 4500 lumen light over the 6040 bad on that circuit.
You can use a 7I84 with 5V I/O
In this case you supply VIN with 12 or 24V
but supply VFIELDA and VFIELDB with 5V
This will make the I/O all 5V
If you happen to have a REV A 7I84
you can run the whole card on 5V only
(VIN,VFIELDA,VFIELDB)
(none of this applies to the 7I84D)
Peter Wallace
Mesa Electronics
Cheers, Gene Heskett, CET.
--
"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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