I´m an old-timer instrument engineer living in the happy 4-20 ma world with PLC´S and simple DCS´S. Now that we are involved in a process control modernization prograam we are receiving messages from our suppliers to go to the bus technology. It seems to be a good solution and we don't want to buy equipment that will be obsolete in the near future. Kindly request help to learn about previous experiences and ways to jump to the new technology. How to avoid confucion in the vast filed of the bus war? What are the premises and justification to change? What would be a logic process control plan for the mill.