Brendan, Any part numbers for the I2C long range transceivers? Nelson If you use the 10bit addressing, you could get up to 1024 PICs on an I2C bus. You'd need the special long range trancievers at each junction, but I don't think that would really be a big problem, since you need trancievers with CAN or RS485 anyway. - --Brendan -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu