Foundation Fieldbus or Profibus?


Thread Starter

automation group

Dear All, We are working a new project for our chemical plant. We are planning to use digital communication advantages for our plant. Which is acceptable to use Foundation Fieldbus or Profibus? 1. Which one is common? 2. Which one is faster? 3. What are the main differantiations for function blocks? Automation Engineer Hi-Tech Technologies Inc. [email protected]
I hope you will never want to put in Foundation Fieldbus to a chemical plant. FF never can make real redundancy, max speed is 31,25kbit/sec, and if you want to use tha control-in-the-field method via FF, you will never reach system reaction time under 2 sec. If you see the time scheduling of a simple one-loop controll, the time of an analog input is at least 700 msec, the simple PID algorithm time is at least 400msec, and the analog output is min. 6-700 msec again. So you will be happy , if you can make your controll in 2 sec cycle-time. And this was the simplest application you will ever use. But the profibus, if you don't have Ex-capabilities, can make 12Mbit/sec, or if you enough Intrinsically Safety of the DP line, you can hold 1,2 Mit/sec. If you need serious Ex-capabilites, you have to use Profibus PA line, this is 31,25kbit/sec, ike, the FF, but it can be redundant.( I mean it could make wire-redundancy, but the FF redundancy is consist of a redundant Link Active Scheduler. So if you cut the wire, your plant is going bye-bye)

Verhappen, Ian

A little slow on the update here but I'm getting through my messages and felt I MUST reply. There are MANY chemical plants around the world SUCCESSFULLY using Foundation Fieldbus which operates at the same speed as Profibus PA, since they both use the same IEC standard to define the physical layer. In a continuous process industry, there are not very many process loops that require less than 2 seconds cycle time and if they do, FF can have cycle times as low as 500 milliseconds. It simply requires GOOD engineering practice and judicious selection of the devices on the network. PLEASE do not mix apples and oranges by comparing Profibus DP with Foundation Fieldbus H1. Foundation Fieldbus HSE, which operates at whatever speed you have your commercial Ethernet components (typically 100 Mit/sec at present) is the competitor to Profibus DP. Unfortunately, the HSE standard was only recently approved so product will only become available later this year. At least host system suppliers support full Fieldbus redundancy, including power supply, signal processor (I/O module) and Link Active Scheduler. Therefore if you have good selection and placement of your power supply AND purchase a paperless recorder also available on the market you can gracefully operate your plant without ANY connections to the host system/central control room OR configure your systems to gracefully shut down. Such is the benefit of being able to run control in the field, which FF is the only bus that can do so. Ian Syncrude Canada Ltd. PO Bag 4009, MD 0032 Fort McMurray, AB T9H 3L1 P 780 790-4079, Cell -799-6017 F 780 790-5190 [email protected]
To Clarify

Foundation Fieldbus HSE = 100Mbit/Sec
H1 = 31,25kbit/sec

Ff Redundantcy = Power, Function Blocks, LAS & Devices (cable is the same as Profibus PA as the physical layer is identical)

Control in the Field LOOP EXECUTION time 100ms (includes Temperature, Flow and Valve)
Imposible with PA

I think the person who wrote the comments below does not fully understand Foundation Fieldbus.