in our process plant one of the vendor is willing to supply foundation fieldbus system for indicating process signals (explaining various benefits of ff system etc.). these signals are not very important but required by operator for continuous plant operation. solution being suggested by the vendor is OK and beneficial for us as far as field side is concerned (megablock, surge suppressor, power conditioner etc.). however,we are looking for a less expensive solution to configure the system and display process values at HMI of existing control system, which is not state of art system (about 15 yrs old, but having standard features for external connectivity as existing at that time). FF vendor is offering its own HMI system and we do not want to invest in additional HMI. can i get valuable suggestions from experienced users, regarding how to achieve this.

thanks in advance.

 

There are always HART and Profibus. Probably most of your field devices are HART already.

Walt

Walt Boyes, FInstMC, Chartered Measurement and Control Technologist
Life Fellow, International Society of Automation
Editor in Chief, Control and ControlGlobal.com
[email protected]

 

Well, you could perhaps help us by telling us what your existing control system is. But anyway ...

There's absolutely nothing wrong with good old 4-20mA, which is most likely what your existing control system uses. While fieldbus systems like FF and Profibus do have many advantages, it does sound like your vendor is trying to oversell you a solution that you don't need and cant afford.

Unless you're prepared to invest in a plantwide solution with instrumentation, actuators, controllers, IO and HMI built to support FF there probably really isn't any benefit for you at all.

Rob
www[.]lymac.co.nz

 

yes. alternatives are available and we can go conventional way also by laying cables to individual field devices and connecting them to already existing Input modules (4-20ma, RTD, Thermocouples, NO/NC contacts etc). however, as devices are spread all over the plant, we think something like fieldbus system can be useful in this case. hence we are exploring this new area of Foundation fieldbus.

thanks.

 

> however, as devices are spread all over the plant, we think something like fieldbus system can be useful in this case. hence we are exploring this new area of Foundation fieldbus.

Then the choice of which fieldbus system to use depends <i><b>entirely</b></i> on the type of control system you already have. What control system do you have right now ?

 

sir, it is Procontrol P13/42 of ABB supplied quite a long time back.

 

> sir, it is Procontrol P13/42 of ABB supplied quite a long time back.

OK, Yes that's a pretty old DCS which has now gone "classic". This means ABB will support your system but is not going to actively develop your controllers or I/O systems ( But it does seem that ABB is trying to at least upgrade your HMI options with to S+ or 800xA)

This means you are back to my original comment that you will need to invest heavily in new controllers, actuators, IO etc to fully support Foundation Fieldbus. At this point you will basically be locked out of upgrading to another ABB control system - because ABB's support for FF is not great. Realistically, Emerson's Delta V is probably the one really good DCS that uses Foundation Fieldbus extensively (yes, I know people will disagree with this opinion) - ABB systems are typically Profibus based. (or proprietary ABB fieldbus systems).

I assume you are already thinking about replacing your DCS at some time in the future. Your decision about which bus system to use now could have a significant impact on that future direction.

If all you're looking for is the cheapest short term solution right now, then its probably 4-20 mA or extending the P13 control bus and locating your controllers closer to your field IO points.

 

sir,

one of the suggestion i have received is to get serial link from FF system (modbus or similar arrangement) and take signals in DCS. but i am not very sure about diagnostics and configuration portion of FF system.

is it possible and what extra component/equipment will be required. can any such vendor/manufacturer guide me.

thanks in advance.

 

What communication protocols does your DCS support

Profibus
Modbus

RedLion controls make a nice translator that might work
Moore make analog to Modbus modules

 

I think its likely that you would be very unhappy with the performance of a modbus serial link. If your DCS supports modbus TCP (And I think the answer is "it does not") then that would be less bad. And of course you still need a new controller to not only run the FF bus but to create the modbus messages as well, and the HMI to give you access to the diagnostic and configuration data. So this does not reduce the cost of your proposed solution in any way.

If you can afford to invest the extra money that an FF solution requires, then you should get a comparison quote for upgrading your DCS from both ABB and another independent vendor.

As I said earlier, ABB's support for FF is not great, but 800xA can support this bus type. You could also look at installing 800xA on your existing Procont system and using the same HMI for a new controller using Profibus. Because the signals are display only and xA would be the HMI for everything then there is no requirement to connect the signals to the old DCS.

 

FOUNDATION fieldbus is a good way to go. Learn more about benefits of
fieldbus here:
http://www.fieldbus.org/images/stories/technology/aboutthetechology/overview/fieldbus_brochure.pdf
However, like stated by others, if your system is old it may need to be upgraded or migrated.

Consider using WirelessHART. It is a very popular solution for modernizing existing plants with a second layer of automation for pervasive sensing of missing measurements beyond the P&ID
http://community.emerson.com/proces...10/03/why-are-there-missing-measurements.aspx

Cheers,
Jonas