Hi simon,
It's the no of drivers for each line i.e TXD/RXD that I said I did this coz I thaught that may be the
single driver getting over loaded but that was not the problem .I have wires the slaves and master in a fashion that is convenient for my specific application and is not a standard one .Take for example your master speakes to your slave when the hoast(PC) tells it to do so and then the master shuts the Host bus and opens the slaves bus to fetch data from them .I am already using serial protocols I did this because I have to use many cards in my scada system and was looking for a way to reduce addressing and components :) .

Yes I am thinking to order an ice cap for me :)

having fun
sanjeev