Debunking the Control Architectures

[RGCook]

Can anyone point me to a good reference that describes and debunks the various architectures currently in use for control systems. In particular, I am interesting in learning more about the following:

1. Analog (4-20ma) and Discrete IO versus
2. ModBus TCP/IP versus
3. Profibus, versus
4. Foundation Fieldbus (H1 and HSE)

I believe that an overview comparing each, pros/cons, etc. would be of great benefit to more than just myself.

I have visited modbus.org and frankly, the information there is too detailed. FF does a better job of describing itself.

Thanks for any help.

 

[ilan7]

RGcook
Stop at:

http://www.easydeltav.com/aboutdeltav/index.asp

and read few lines about the Fisher-Rosemount Delta-V system.
Then you can go to:

http://www.easydeltav.com/video/product/index.asp

and watch some videos online (each about 5 min.)
Think it will give you some idea.
You can also stop at

http://www.smar.com

and look for the systems explained there.
Think the easyest way is to contact the agent of one of those companies and ask them to try and convince you to buy thier product after explaining it.

 

[FrancisL]

Definitions of debunk on the Web:

expose while ridiculing; especially of pretentious or false claims and ideas; "The physicist debunked the psychic's claims"

Do you really mean "debunks" ?

 

[RGCook]

What I mean is...why so many architectures and "open" standards. I didn't even mention DeviceNet or others that I am not even aware of.

Perhaps Debunk is a harsh word. But I am really trying to understand which ones merit investigation and which ones are just "piling on".

 

[controlnovice]

A few years ago, when a fieldbus standard was in the planning, no one could agree on one standard, so the committee decided to make several standards. That didn't go over well with the head of the committe and he quit (I think that was the story). I think 7 standards came out of that committee. I quess everyone agreed to disagree.

Be careful of what you see at

http://www.easydeltav.com.

I have installed several instrumentation networks (on DeltaV too), and it is NOT that easy. Their claims, just like any salesrep's, are not as they seem.

For example, they claim that commissioning one instrument is reduced from 1 hour to a few minutes (15 I think in their propaganda). Complete rubbish! Same goes for thier claim to reduce Engineering time. Garbage.

If you decide to install an instrumentation system at a plant, be sure that the plant has the personnel to maintain it. It is much more difficult than a standard 4-20mA system to troubleshoot for many maintenance personnel. Even with training. But it is nice to have reduced cabinet space and less wiring(if done correctly).

After installing several networks, I still recommend standard HART for most plants.

 

[jsummerfield]

Controlnovice is correct that commissioning is not necessarily as optimistic as suggested by marketing information. However, with HART the AMS software on a notebook PC is very helpful. I bet that it is helpful with Foundation Fieldbus tm too.

John

 

[RGCook]

Thanks for your helpful response guys. An EI&C friend recently told me to stick with HART as well. We did put three Micromotion coriolis on Modbus in the last plant but I think we will hold the line and see how it goes.

Appreciate the input.

Bob

 

[controlnovice]

Yes. AMS is very useful for HART instruments. And AMS is very useful for Foundation Fieldbus instruments as well. It is definately better than standing with a 275 HART communicator in the field commissioning instruments in Northern Canada during winter, or Houston in August.