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Groups > comp.arch.embedded > #28310
| From | Grant Edwards <invalid@invalid.invalid> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: RS485 over optical fiber cable |
| Date | 2018-11-02 18:21 +0000 |
| Organization | PANIX Public Access Internet and UNIX, NYC |
| Message-ID | <pri4k3$r8$1@reader1.panix.com> (permalink) |
| References | (2 earlier) <prc4e3$chj$1@dont-email.me> <prccn8$spf$1@reader1.panix.com> <prcljq$9v1$1@gioia.aioe.org> <prcmch$2uj$1@reader1.panix.com> <prhkck$e2s$1@dont-email.me> |
On 2018-11-02, pozz <pozzugno@gmail.com> wrote:
> I will have two battery-powered devices, connected by a RS485
> link. In this case, both devices are isolated from mains and Earth.
> Do you think it's safe to avoid signal ground connection between the
> two devices in this situation?
Yes, it's "safe" (nothing's going to melt or burst into flames and
kill people). No, I wouldn't depend on it working reliably (though it
probably will).
> It's difficult to me to understand what happens to the common-mode
> voltage at the receiver, if its power supply (battery) is isolated from
> the rest of the world.
There will be some sort of current leakage that will cause the the
signal ground to "float" to some voltage relative to the two signal
wires, but it's pretty difficult to predict exactly what happens.
It's far easier to understand what happens when you _do_ have a signal
ground connection.
--
Grant Edwards grant.b.edwards Yow! I'm using my X-RAY
at VISION to obtain a rare
gmail.com glimpse of the INNER
WORKINGS of this POTATO!!
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RS485 over optical fiber cable pozz <pozzugno@gmail.com> - 2018-10-30 15:00 +0100
Re: RS485 over optical fiber cable raimond.dragomir@gmail.com - 2018-10-30 07:26 -0700
Re: RS485 over optical fiber cable pozz <pozzugno@gmail.com> - 2018-10-31 12:41 +0100
Re: RS485 over optical fiber cable raimond.dragomir@gmail.com - 2018-10-31 05:55 -0700
Re: RS485 over optical fiber cable Grant Edwards <invalid@invalid.invalid> - 2018-10-31 14:03 +0000
Re: RS485 over optical fiber cable John Speth <johnspeth@yahoo.com> - 2018-10-31 09:35 -0700
Re: RS485 over optical fiber cable Grant Edwards <invalid@invalid.invalid> - 2018-10-31 16:48 +0000
Re: RS485 over optical fiber cable pozz <pozzugno@gmail.com> - 2018-11-02 14:44 +0100
Re: RS485 over optical fiber cable Richard Damon <Richard@Damon-Family.org> - 2018-11-02 11:00 -0400
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-11-02 20:42 +0200
Re: RS485 over optical fiber cable raimond.dragomir@gmail.com - 2018-11-02 08:18 -0700
Re: RS485 over optical fiber cable Mike Perkins <spam@spam.com> - 2018-11-02 15:22 +0000
Re: RS485 over optical fiber cable Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-11-02 21:31 +0200
Re: RS485 over optical fiber cable Mike Perkins <spam@spam.com> - 2018-11-02 20:12 +0000
Re: RS485 over optical fiber cable Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2018-11-02 23:57 +0100
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-11-03 01:18 +0200
Re: RS485 over optical fiber cable Mike Perkins <spam@spam.com> - 2018-11-03 19:05 +0000
Re: RS485 over optical fiber cable Richard Damon <Richard@Damon-Family.org> - 2018-11-03 17:36 -0400
Re: RS485 over optical fiber cable gnuarm.deletethisbit@gmail.com - 2018-11-03 19:49 -0700
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-11-04 07:50 +0200
Re: RS485 over optical fiber cable pozz <pozzugno@gmail.com> - 2018-11-05 09:40 +0100
Re: RS485 over optical fiber cable Richard Damon <Richard@Damon-Family.org> - 2018-11-05 06:45 -0500
Re: RS485 over optical fiber cable Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2018-11-05 09:12 -0800
Re: RS485 over optical fiber cable Grant Edwards <invalid@invalid.invalid> - 2018-11-02 18:21 +0000
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-11-03 00:02 +0200
Re: RS485 over optical fiber cable pozz <pozzugno@gmail.com> - 2018-11-02 14:36 +0100
Re: RS485 over optical fiber cable "Mat Nieuwenhoven" <mnieuw@zap.a2000.nl> - 2018-10-31 16:32 +0100
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-10-31 22:41 +0200
Re: RS485 over optical fiber cable Chris <c@b.a> - 2018-10-31 12:16 +1100
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-11-02 06:52 +0200
Re: RS485 over optical fiber cable Robert Wessel <robertwessel2@yahoo.com> - 2018-10-31 09:11 -0500
Re: RS485 over optical fiber cable peter jakacki <peterjakacki@gmail.com> - 2018-11-12 19:57 -0800
Re: RS485 over optical fiber cable upsidedown@downunder.com - 2018-11-13 08:09 +0200
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