is there any one can explain the technical resons of non implementing redundant ring networking in DCS control bus whre as it's a common practice in Substation/SCADA based automation?
Actually, one of the very early DCS from Leeds and Northrop, the MAX 1, used a dual path counter-rotating ring network. It was very reliable, but also very costly. When L&N went out of business, the MAX 1 product was sold to Metso Automation. Metso continues to offer this architecture with the ring bus now based on Ethernet. See this website: http://www.metso.com/Automation/ip_...Document&mid=C2ADD4741ADBD4B8C22575C100397067
Most DCS offer other forms of network redundancy - the ring method is only one of such methods. Foundation Fieldbus HSE offers n-level redundancy when necessary.
In answer to your question, I believe that the process control networks have been so reliable that most suppliers have not invested in other reliability techniques.
By the way, using Foundation Fieldbus with Control in the Field (CiF) places the most critical parts of automation in the most reliable part of the network, the field instrumentation.
Dick Caro
CEO, CMC Associates
Certified Automation Professional (ISA)
Buy my books at the ISA Bookstore:
Wireless Networks for Industrial Automation
Automation Network Selection
Consumers Guide to Fieldbus Network Equipment for Process Control
