I tried opto isolators and they did not work without errors while capacitive insulation barriers did. It was a suprise and I can't tell why. I think most devices including opto have a limited dv/dt tolerance.
On Sun, 3 Apr 2016 12:36:23 -0500 Danny Miller <dan...@austin.rr.com> wrote: > Well, if you have 2 differential wires with a simple optoisolator at the > far end, ground noise/ground loops would have no effect whatsoever. You > don't need a ground. There would be no place to put a ground. There are > no common-mode issues. The slave device's ground could be +300VDC above > the master's ground. > > However, RS485 doesn't spec that way. The ADAM isolator box I have > probably has optos inside, but has to make an RS485 output- which is a > low-voltage DC differential in relation to a known ground. > > Danny > > On 4/3/2016 5:21 AM, Nicklas Karlsson wrote: > > On Sat, 2 Apr 2016 11:34:25 -0400 > > Gene Heskett <ghesk...@wdtv.com> wrote: > >> ... > >> Given all that, I do not see how, in a noisy industrial environment, or > >> even here at the Heskett's home camp, it can be error free unless an > >> optical translator, bidirectional, is used at BOTH devices terminals. > > I am not sure about the optical translators. Why however I can't tell for > > sure. > > > >> ... > >> > >> The question then seems to be, is who makes these rs485 to opto fiber (or > >> even to RJ45 jacks & cat5 or cat6 cable since it doesn't have this > >> common mode noise problem that I am aware of), bidirectional translators > >> and at what cost. > > Ethernet which use the RJ45 connector have tranformer for insulation. I > > have experienced communication errors over Ethernet then communicating with > > inverter. > > > > > > Nicklas Karlsson > > > > ------------------------------------------------------------------------------ > > Transform Data into Opportunity. > > Accelerate data analysis in your applications with > > Intel Data Analytics Acceleration Library. > > Click to learn more. > > http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > ------------------------------------------------------------------------------ > Transform Data into Opportunity. > Accelerate data analysis in your applications with > Intel Data Analytics Acceleration Library. > Click to learn more. > http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
