solarwind ha scritto: > On Mon, May 18, 2009 at 3:17 PM, Isaac Marino Bavaresco > wrote: >> It appears somebody found that a node always sees the data it is >> transmitting, even when there is another node transmitting. If so, then >> it may be not possible to detect collisions at all. > > How is this possible? From my experience, standard RS485 drivers such as SN75176 or ADM485 are *really* sensitive to differential voltage. So, then can "read" a voltage even if the A-B lines are short circuited, say, 1 meter past their inputs. Or if another station on the net is transmitting, but is more than some meters apart. So, a theoretical simple and good approach - listen back to what you say - does not work on the fiels. Dario -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist