On Sat, 29 Dec 2018, Gene Heskett wrote:
Date: Sat, 29 Dec 2018 17:34:48 -0500
From: Gene Heskett <ghesk...@shentel.net>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] [utf-8] 7i77 ? Trying to understand TB2
On Thursday 27 December 2018 22:20:35 Greg Bentzinger via Emc-users
wrote:
.
7i77 ?? Trying to understand TB2
Pin 1 ?? VFIELD ?? FIELD Power 8-32V
Pin 2 ?? VFIELD ?? FIELD Power 8-32V
Pin 3 ?? VFIELD ?? FIELD Power 8-32V
Pin 4 ?? VFIELD ?? FIELD Power 8-32V
Pin 5 ?? VIN ?? FIELD I/O Logic Power 8-32V
Pin 6, 7 ?? NC
Pin 8 ?? Ground ?? COMMON
So ?? are pins 1-4 common to each other, not common and can be supplied
different voltages, common but redundant to allow for greater current
transfer. Everyone I have ask has given completely different and
conflicting answers. Since I have no idea what the encoder current
draw will be I will be supplying TB1 with its own 5V powersupply and
thus W1 will short the 2 pins on the right (farthest from the DB25) I
have a second 24V powersupply which I have wired to each pin 1-5 with
ground on pin 8. My notes show I did this wiring 12/3/17 and have yet
to actually power it up as have yet to obtain a clear definitive
answer as to if this is proper or a potential smoke machine.
Greg
To further confuse the issue with my 7i76, it W1 is moved to the right,
no 5 volt feed goes there at all, the are several 5 volt inputs on
another terminal, so read that bit about moveing W1, and reread it
again. I think if a higher voltage field power is applied, it may be
only used for certain outputs. like 15 volts for controlling 12 to 15
volt rated relays. That also implies the use of free wheeling diodes on
the relay coil to protect the boards chips so don't forget that.
There is no logic power (5V) connection the the Field I/O part of the 7I76 or
7I77. It is completely isolated from the 5V part of the board so entirely
depends on field power. VIN (that supplies the low voltage regulator on the
field I/O side) can come from a different source. For most uses you simply
leave W1 in the left hand position and supply 8-32V field power.
The output driver chips do not require flyback diodes unless you have large
loads (small relays etc dont need diodes but solenoids/contactors do)
The reason flyback diodes are not required for small loads is that the outputs
have a build in zener--> gate clamp that clamps the maximum drain-source
voltage to ~40VDC, basically slowing the MOSFET turn-off. This works fine for
small loads but does dump the stored inductive energy into the MOSFET
(If a flyback diode is used the energy is dissipated mainly in the coil
resistance)
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
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)
Genes Web page <http://geneslinuxbox.net:6309/gene>
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
Peter Wallace
Mesa Electronics
(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
