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
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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
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