David Woolley wrote: > Message-ID: <[EMAIL PROTECTED]> > From: Uwe Klein <[EMAIL PROTECTED]> > >>the same happened if the currentloop in rs422 was broken > > > Although the relevant parts of the article seem OK, rs422 is not current > loop. I think current loop is so old that it pre-dates current loop. > RS422 is bipolar balanced. Current loop is unipolar, and likely to be > unbalanced. You are right there: RS422 is a +-5V shift symmetric driver that works on an end terminated line of fixed impedance. ( usually point to point ) The receiver evaluates the voltage across the wire pair. RS485 is the same but bidirectional and multi station. The transmission line is terminated on both ends, the line accomodates a limited number of taps. Currentloop is what forex old ttys are connected, essentially a telephone line. > > I think RS422 receivers are biassed in the same way as RS232 ones so that > a physical line break doesn't result in a spacing condition, and therefore > a break condition detection. (I suspect this is why RS232 data and control > lines have opposite senses, so that disconnected goes to control false, but > to data marking. I would have to read up on my old datasheets for the SN75xxx thingies ;-) > > Incidentally, your copy of Mozilla seems to have been configured not to > request German language responses; is that what you intended? never decided this, it's the default with using Mozilla with the default (en) language settings ;-)
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