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New "DCS" control system selection
Requesting member feedback for the replacement selection of an existing petrochemical control system "DCS".

I am seeking cost effective solutions for replacing my Rosemount System 3 control system.

I have decided that using remote I/O multiplexers for the HART smart analog and 120VAC Discrete I/O provides several significant advantages. "Home run" twisted pair cables from local area junction boxes would be replaced with an open protocol, high speed industrial Ethernet like Profinet, or Modbus TCP/IP to a server/HMI. While researching this over the last 6 months, I have discovered several multiplexer/controller solutions that are are rated for Class I, Group II environments.

The current list that I believe are strong contenders include Delta V, MTL MOST (Now GE Fanuc), Siemens S7 & PCS7 and Yokogawa Stardom FCN. I invite other suggestions. There are numerous features that I would like to see in the "open" system such as OPC or OPC UA, redundant hardware, easy to configure and troubleshoot, an inexpensive historian attached to the company LAN and minimum Licensing fees. I am inviting both pro and con comments, either directly and via this forum, on selection of a new cost effective "DCS" that would be a true distributed control system.

I feel this open discussion could also provide help to others with older control systems. My I/O count is over 1000 points. A spreadsheet comparing features of potential candidates would be of strong interest.

Thank you for your response.

georgewhaley3 at aol. com

By Y.K.JARIWALA on 4 September, 2008 - 12:30 am

Would you give us break-up of IO counts

a] Process IO

C] Any third party interface?

D] Hazardous Area Zone, GRIIA,IIB or IIC?

E] Utility area Input/Output

Appreciate your feedback.

iconcnl at vsnl. net

By GeorgeWhaley3 on 11 September, 2008 - 12:42 am


Thanks for your questions.

I have worked in the industrial field for 30+ years and my response below is what I would typically find in most chemical plants. This should apply to a lot of other readers. Just maybe on a smaller scale.

My I/O count is roughly this
400 each 4-20 MA HART Smart inputs
100 each 4-20 MA HART Smart outputs
100 each 100 OHM Plat. RTD (direct input)
8 each 0-10 VDC
400 each 120vac discrete switches for:
(Motor starters, Solenoid coils, valve limit switches, etc.)
PID loops are about 100.
We are not SIL or IS rated but do have software interlocks (permissives).

Most of my Plant is Class I, Div 2 Group B or C so I would like to stay with Group B rated equipment.

There are not any interfaces to the existing RS3 system but the Data on a new "DCS" system would need to be ported to a LAN for importing into a spread sheet and trouble shooting.

Feel free to contact me directly in order to answer simple questions.

Hi George,

With these I/O counts, we would preferred DCS with single controller, having IO capacity of 2000 I/O, which simplifies the implementation & performance.

What is PID scan time?
Do you have batch recipe management?

iconcnl at vsnl. net

I have been programming PLCs & DCS systems for 15 years. Over that time I have worked with a lot of bad systems. In my opinion, for what you are asking and based on my experience, Delta V is the best DCS system on the market. It is very easy to use, it has many interfaces, fieldbus, devicenet, modbus, asibus, modbus TCP, Allen Bradley Ethernet, OPC, Hart, Wireless transmitters, remote I/O, and it has an interface to RS3 I/O in case you wished to cut down on your construction time and cost.

If there were a drawback to Delta V it would be on the licensing side. Emerson is proud of their licensing.

That's my 2 cents.

Hey some new information I thought you might be interested in regarding Delta V. I have a client running an older version of Delta V and is interested upgrading to the current version. They have been told to upgrade not only do they need purchase 1 year foundation support but they have to pay for the past three years of not getting support. That is the silliest thing I have ever heard. My client is now asking me if they can purchase new PCs and load the old software just to avoid having to pay for 3 years of tech support they did not receive, cha-ching. As an integrator it's still the best system on the market but I'm not the one paying $$ for this level of customer satisfaction.

By Dave Ferguson on 6 September, 2008 - 2:06 pm

Hands down 2 things I absolutely hate about DV and will not recommend to anyone because of..............

Licenses, licenses, licenses ............they are still living in the old iron DCS world, sort of like IBM "Those PC's will never replace our mainframes". I did a project that had $200K of licenses.

The distribution model is messed up, their distributors are also the only ones you can buy their products from (or at least this is what we have been lead to believe by Emerson, and therefore there is a conflict of interest in showing you anything about it.

There are not many (or at least many I have met) Integrators who are DV experts. You may be an exception, unless you are an Emerson Distributor also?

Dave Ferguson

I am not an Emerson Distributor, just an integrator that's been working with Delta V for 11 years now.

I agree with your assessment of the licensing, which I noted in my original post. However, as an integrator, there's no other system I'd rather work with. But that's just me.

I would check out MTL8000 series or Most. I believe they make their own controllers and also manufacture modules for other DCS companies (including DV, I think).

Let us know what you decide on.


MTL recently sold the MOST system to GE Fanuc, who are just pleased as punch with their new acquisition.

Walt Boyes
Editor in Chief
Control and
Read my blog SoundOFF!! At

While I am not a Delta V fan by any means, I would agree that if you are an existing Rosemount user, then DV may be the right way to go for you.

However, you may also want to include ABB's Compact Controller range on your list. The Compact products range is a cut down version of ABB's 800xA system

(While the ABB 800xA system is large & powerful, it has lots of licenses, etc. etc. which you are trying to avoid. The "Compact Products" are aimed at smaller to medium sized installations.)

The S800 I/O modules support Profibus and HART and function as your field "I/O multiplexors".

The AC800M Controllers Support Redundancy.

The HMI system supports up to 5 PC based operator workplaces plus any number of Panel type HMIs.

The system is OPC and OPC-HDA compliant (Much more so than Delta-V, which is quite proprietary in some areas).

Pricing wise, Delta V and ABB should be in the same ballpark.



I like the DCSs from ABB. Freelance for smaller systems and 800xA for larger systems. The licensing has been straightforwards.

I really don't like Delta V and would not recommend it. The reasons, as noted by others, are the weird pricing structure and also the VAR channel structure. As someone who has worked with integrators I've seen too many times where Emerson do a sneaky back-room move to cut out as many players as possible and only have their own people involved.

You also have your high end process automation controllers. Their weaknesses are in the PAC-SCADA tie-in which isn't always as good as a true DCS. Rockwell Automation and Siemens come to mind. Siemens have made a decent effort at merging Step7 and WinCC to get PCS-7 but at the end of the day it is still Step7 and WinCC and they are different packages written by different engineering groups.

All that being said, I still find a lot of DCS software a bit "behind" in some ways as far as being easy to use goes - that is compared to most PAC programming tools. However, I don't think anyone has mastered the SCADA or HMI end yet.

If you're willing to live with a PAC then you can also consider Wonderware ArchestrA or GE's iFix. They are both very, very good SCADA packages.

Citect often gets recommended in the same sentence as Wonderware, but given its clunky dBASE IV innards, I would not recommend it.

Dear George,

I have personal experience with Emerson DeltaV systems at different plants. I have converted 3 plants based on HB system, Foxboro I/A series system and Provox system to DeltaV systems. It can support any type of topology and any kind of interface in the market. Very easy to port old data as Emerson has programs that convert your previous configs to new format seamlessly. Plant down time is minimal. Believe it or not, a cleverly designed Provox migration might only take 2 hrs and total conversion a few days. To put it straight, it is the best product in the market due to ease of installation, commissioning and maintenance. Spare parts cost is reasonable and competitive. User interface is the best in the market.

Every product owner has right to safeguard its product, and there comes the licensing and fees issue. But a properly negotiated deal can land at very attractive price. I converted my 550 point polyester plant HB based system to DeltaV for only $120,000 US. Included software migration, hardware integration, FAT/SAT 02 operator + Proplus + application station with web server.

Next I converted 400 points plant for $65000 US (same scope as above but 1 operator station). So price is far cheaper than thought. I would recommend DeltaV.

Note: I have also designed water transmission system based on ABB 800 series (28 controllers, countless I/O ) but was not impressed as compared to DeltaV.

Emerson certainly have tools for migrating RS3 and Provox to DeltaV but you end up with RS3 or Provox code in a DeltaV controller. These tools make no effort to take advantage of modern programming techniques they just replicate what was in the legacy system - dead code and all. When you go down the replication route you get what you pay for - 15 year old code in a new box. However when you consider that most sites only upgrade their control systems every 10 to 15 years this may result in a major support issue given the knowledge of RS3/Provox is fast disappearing not to mention lost optimisation opportunities, difficult expanding or modifying the code and little or no documentation.

On the SI issue there are a number of SI's who do a very good job on DV, in some instances better than Emerson, however Emerson does its best to dissuade clients from using SI's and also makes development licenses prohibitively expensive and renewable every year, in some instances refusing to sell development licenses to SI's they see as competitors. Then again a savvy buyer will never be dictated to by a vendor what they can and can't do.

To keep existing wiring and shorten the down time Invensys Foxboro IA system offers a nice solution.

They replace the IO cards and keep the field wiring. Make the system technology up to date.

Please take a look. I revamped myself 2 plants using their technology

Patrick Viskens

Reditech engineering

After looking at several control system manufacturers and submitting an RFQ to several mfgs and also system integrators, a decision was made to go with DeltaV. Some of the reasons were:

1. Initial DCS cost of hardware, software and licensing fees were less than half of several other solutions. Very good hardware and software pricing (discounts) were obtained from our local rep. and the I/O (DSTs) and software were tagged with one time licensing.

2. Internal support for DeltaV programming already existed at our plant due to other units using DeltaV. This helped drop engineering costs to about a quarter or a third of outside contractor engineering. (A very large savings.)

3. Operators from other units were available that have DeltaV training.

4. DeltaV offered an excellent hardware and software solutions and some of the solutions were COTs (Commercial of the Shelf) which I found that I could purchase at a significant savings. The local rep worked with us on providing the parts we wanted to purchase from him. He did not balk at our providing much of the hardware and programming cost of the new system.

5. Annual support costs were about the same as other mfg. offerings. This turned out to be less of an expense than I expected. However, it will be interesting to see how much this increases in future years.

6. Emerson is still expanding and offering new options for improving process controls. They are a significant leader and I expect support for their products and software support will still be available 20 yrs from now.

I appreciate the feedback and hope this may help you. Thank you for your responses.

georgewhaley3 at aol. com

By Paul Mathew on 3 January, 2009 - 3:41 am

During eighties and nineties, economic analysis was also used as a tool to select the ideal solution from options including DCS and single loop controllers. With the advent of technology the scenario has changed and DCS and PLC based systems has become very cheap and naturally all previous cost comparisons has become obsolete.

Do you think that cost comparison is relevant today?

Expert comments on the subject are invited.


I would recommend speaking with Phil Corso regarding a unique way to monitor and safely control your system(s) without license fees. He can be contacted at cepsicon at aol. com.

By Kevin Wynne on 27 January, 2009 - 4:05 pm

I would have to agree with the high cost of licensing with Emerson. Other than that, the hardware is very reasonable, the ease of expansion if very nice, and as I am currently converting an RS3 system to Delta V, the interface and ease of programming is second to none. If you have marshalling panels in the field there is an easy way to convert both analog and contact IO. (Willing to explain but don't want to take the time here/now). There are some issues with PLC communication unless your spring for the VIM from Mynah, but then you have seamless Ethernet IP and can pull entire registers as a single license. If you want more info I'll try to help.
Kevin Wynne