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 <[email protected]> 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 > [email protected] > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
