); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Pablo Alvarez Sanchez wrote: > Dear timing colleges, > > At CERN we are considering the possibility of using Ethernet as a real > time field bus. > We may use IEEE 1588 to distribute precise UTC and Ethernet Powerlink or > a similar home made product to guarantee real time. > > In order to have full control over the network we are thinking of > designing our own hardware using FPGAs (including the physical > interface). It looks like we will end by implementing 100Base-TX or > 10Base-T rather than gigabit Ethernet, just because it looks much more > robust and simpler to design. > > > > 1) Two ways calibration performed in IEEE 1588 needs a symmetric path > between nodes. In a presentation made by 'Timing Solutions', they say > there is a 10% of asymmetry on the path for 100Base-TX. I guess this > comes from the fact of using one pair for the go and a different pair > for the return path. > Do you have some figures for the two ways asymmetry on a single pair? > Pablo
There should be none the propagation delay of a single pair should be the same in each direction. The asymmetry between pairs is due to the slightly different lengths involved. Each pair uses a slightly different number of twists per unit length. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.