On Thu, 21 May 2020, andrew beck wrote:
Date: Thu, 21 May 2020 14:05:02 +1200
From: andrew beck <andrewbeck0...@gmail.com>
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] mesa 7i76 spindle encoder not counting suddenly
hey peter
I am using a 5i25 and 7i76 combo. and currently supplying power from the
5i25
so I don't particularly want to make the computer ground the same as
everything else lol.
Except the the computer ground is frame ground and the common for the servo
drive quadrature outputs should also be returned to frame ground
it sounds like I need to connect a external 5v powersupply up to the 7i76
and change the jumpers around to suit. and then connect up everything
again.
That will not change anything ground related
I have a 7i89 coming soon and I will wait until then to sort this out I
think. I will just disconnect the encoder feedback for now and make some
parts.
as my servo drives are tuned now.
its a bit silly that it only just now failed though. it was working
perfectly yesterday.
regards
Andrew
Do you have valid differential signals across the A /A and B /B pairs?
( >2 V absolute across the pins, that is more positive than +2V or more
negative than -2V )
Thats would be the most diagnostic test
On Thu, May 21, 2020 at 1:46 PM Peter C. Wallace <p...@mesanet.com> wrote:
On Thu, 21 May 2020, andy pugh wrote:
> Date: Thu, 21 May 2020 02:33:16 +0100
> From: andy pugh <bodge...@gmail.com>
> 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] mesa 7i76 spindle encoder not counting suddenly
>
> On Thu, 21 May 2020 at 02:22, andrew beck <andrewbeck0...@gmail.com>
wrote:
>> I read a post you made while ago saying that the 5v and 24v
powersupplies
>> need to be within a certain threshold to work well. or else they need
to
>> be commoned together
>This is really a question for PCW. I think that they need to be within
>12 (17?) volts to work.
There should be no substantial common mode voltage. That is the
quadrature source and the 7I76E must have a common ground.
The input common mode range on the 7I76E encoder input is -7 to +12V
you can easily exceed this (and even damage the reciever chip)
if the source and 7I76E do not have a common grouns
>> so if I test between the 7i76 mesa 24 field power ground ( this is the
same
>> power as the servo drive control power) and the logic 0v on 7i76 I
should
>> get close to 0v is that correct?
>The important thing is that the difference between + and - is a couple
>of volts or so (positive or negative) and in both states the
>difference between each input and 7i76 gnd is <12V (or possibly 17,
>the number is in the manual)
--
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
???? George Fitch, Atlanta Constitution Newspaper, 1912
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Mesa Electronics
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(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
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