Best Fieldbus for Discrete Instruments (On-off valves)?
Best Fieldbus for Discrete Instruments (On-off valves)?
(OP)
The more I study the possiblities the more uncertain I become about what to use. We are doing an estimate for a chemical process plant where Foundation Fieldbus(FF) has been decided for use with Analog - Transmitters and Positioners.
The question is what to do with the on-off valves and switches? My first impression was that FF would be overkill and unecessarily expensive. I then moved to the Profibus world. It seemed to be very similar on the hardware level which I liked. However when I began to look at the availability, the first two common topworks companies I checked (in the US)seemed to only be set up for the high speed version that requires separate power and not the PA version which does not.
This plant is very large with two areas with concentrated process and then many small areas spread way out- a tank half a mile away , wastewater, etc.
The Actuator and topworks people seem to more set up for AS-i bus than anything but I was shying away from it because of its length limitations -100 meters(300 meters with repeaters).
I've received some component prices and was surprised to learn that profibus topworks were not much less expensive than FF.
We are expanding an existing ABB DCS system and I really hate the idea of having FF for analog and back to the wire-everything-standard I/O for the discrete stuff.
If anyone has gone through this and can give me some conclusions you reached , I would much appreciate it.
The question is what to do with the on-off valves and switches? My first impression was that FF would be overkill and unecessarily expensive. I then moved to the Profibus world. It seemed to be very similar on the hardware level which I liked. However when I began to look at the availability, the first two common topworks companies I checked (in the US)seemed to only be set up for the high speed version that requires separate power and not the PA version which does not.
This plant is very large with two areas with concentrated process and then many small areas spread way out- a tank half a mile away , wastewater, etc.
The Actuator and topworks people seem to more set up for AS-i bus than anything but I was shying away from it because of its length limitations -100 meters(300 meters with repeaters).
I've received some component prices and was surprised to learn that profibus topworks were not much less expensive than FF.
We are expanding an existing ABB DCS system and I really hate the idea of having FF for analog and back to the wire-everything-standard I/O for the discrete stuff.
If anyone has gone through this and can give me some conclusions you reached , I would much appreciate it.





RE: Best Fieldbus for Discrete Instruments (On-off valves)?
In my experience, we use the SIS with digital outputs to control the solenoids. The valve position is still typically done with open and closed position switches. I too am a interested in feedback related to industry trends for the safety shutdown valves including partial stroke testing, position transmitters, Fieldbus, etc.
RE: Best Fieldbus for Discrete Instruments (On-off valves)?
I'm going to a ABB Automation World Conference at the end of this month in Houston and hope to learn a lot in their workshops.
I'll share when I get back.
RE: Best Fieldbus for Discrete Instruments (On-off valves)?
Our plants are very small, and we don't have the lengths you are concerned with, although for a couple of the AS-i segments, we did need repeaters.
My preference is AS-i bus. But I think it is more for the interface between it and our DCS system (Emerson's DeltaV). I don't see one advantage over the other in hardware, network or ability.
For hardware, I really like StoneL's offering on valves and especially the disconnect switches for hazardous areas. You can disconnect individual instruments from the main trunk line without disruption to anything else.
Foundation Fieldbus is not a good solution for discrete instrumentation.
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RE: Best Fieldbus for Discrete Instruments (On-off valves)?
RE: Best Fieldbus for Discrete Instruments (On-off valves)?
RE: Best Fieldbus for Discrete Instruments (On-off valves)?
One thing I didn't like about StoneL's design was the lids, or covers, for the EXP rated enclosures. If the lid was dropped, it can go "out of round", and never get the lid/cover back on the device.
But still much easier than having to remove/undo the screws or bolts of the other manufacturers.
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RE: Best Fieldbus for Discrete Instruments (On-off valves)?
RE: Best Fieldbus for Discrete Instruments (On-off valves)?
http://www.as-interface.net/System/
It is simple to use, simple to connect (devices just push through the rubberized cable to make contact with power and data). There seems to be plenty of devices that can connect so it is not a proprietry protocol.