Can Siemens PCS7 be considered as a True DCS?

This is not strictly true. Recently we chose PCS7 over T3000 on 1200mw power plant, all the drop menus are available through EON Germany (Grey logix). Remember all the bottom end is manufactured by Siemens A&D, it is only interface that is Siemens PG. The biggest advantage is that the end user is not locked in to long term contracts and the equipment is available from almost anywhere. PCS7 is increasingly used in the power industry. Commercially it is also a third of the price for the same functionality.
 
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Muhammad AlHawamy

I have been working in a consultancy firm. I have happened to evaluate bids for my clients. Based on my experience I would say Siemens PCS7 is not a reliable solution as DCS. ABB 800xA can be regarded as true DCS.
 
Dr. R. Murugesan,

Please add one Chinese brand: Hollysys MACSV
This is a DCS product from Hollysys, a listed company in NASDAQ.

-----------------------
Jerry Zeng
DCS Application Engineer
zengshaojie at hollysys. com
Hollysys Asia Pacific, Singapore
 
Muhammad,

What are the key factors according to which you concluded that ABB's 800xA system is truly DCS? I'd like to see what your evaluation table looks like.

Thank you.
 
Dear Mr. Muhammad,

Would you please tell us your technical reasons behind evaluating PCS7 as not reliable?

I can understand if you say PCS7 is not a true DCS but not a RELIABLE solution makes me wonder how you judge a solution as not reliable! Would you please tell us what kind of customers you have? I mean Oil & Gas, Pharmaceutical or power plants or what?

One last thing, what is it that you could find in ABB 800XA and couldn't find in PCS7? I'm really curious to know your answers.
 
Wrong.
1/p * 1/p = (1/p)^2
- in case of series connection.

Dual redundancy - parallel connection.

 
My experience is with ABB legacy system and I am new to PCS7. My first reaction was that this was not a true DCS as I as accustomed to. The reliability one person mentioned probably is referencing redundancy of the system. More later...
 
D

Dr. R. Murugesan

Dear Mr. Jerry Zeng,

Thank you for your response and for your inputs.

Veritably, there are interesting additions across the globe to the increasing family of DCS for industrial automation.
I had the opportunity of evaluating Supcon make DCS of Chinese origin.

Can you please provide salient features of the brand Hollysys MACSV)with a list of successfully implemented installations?

I am grateful to all the contributors to this valuable topic.

Dr. R. Murugesan
 
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Dr. R. Murugesan

Dear Mr. Mike Davis,
Thank you for your valuable contributions to this topic. I agree fully with your views on the treatment of the subject on 'reliability'.

The availability of the system is of paramount importance, especially in view of harsh operating conditions. Most DCS vendors confuse this term only relating two parameters, vis: MTBF and MTTR.
In my view, the availability of the total DCS needs to be addressed considering contribution from each of the following factors:
* system failure
* control for one critical closed loop
* control for one non-critical closed loop
* control for one critical open loop
* control for one non-critical open loop
* all functions of one operator station
* one type of operator request function
* main data bus failure, back-up in operation
* main communication controller failure, back-up in operation
* main processor in one DPU failure, back-up in operation
* process I/O module in one DPU
* one complete DPU failure

Each system vendor would have in place as part of QIP to test above features with assignable weightage factors so put together, a total system availability of 99.7% or more can be guaranteed.

I would be very grateful to receive inputs from you or other professionals on the above.

Regards,
Dr. R. Murugesan
Consultant-Industrial Automation & Change Management
 
To respond to the original question, I believe the PCS7 is not a DCS. My point of reference is the ABB InfiNet90 system. On the regulatory logic, the PCS7 system may have copied a DCS pretty well. However, when you start looking at batch control it becomes pretty obvious that the PCS7 system still very much a PLC like running Wonderware.
 
F
Dear Jerry,

Thank you for introducing Hollysys.

Please share with us some special features that Hollysys MACSV can offer. Any project references in S.E. Asia?

Francis

------------------------
Francis Tan
TRIPS Automation Singapore Pte Ltd
(a division of TRIPS Group, Germany)
 
Rading all the comments to the original question I must say something based on my 18+ years of expereince with the process industries.

Way back in the 90's. Yes there were clear demarkation between a DCS & PLC system simply because both were built to serve different funtions & applications. However nowadays this clear line no longer exists as we can use the power of telecommunication to distribute the PLC & I/O's too over greater disctance thus making them distributed & using powerful controllers all operation are possible in all controllers today.

To say PCS7 is not a True DCS would be wrong as it truly has evolved into a Hybrid DCS system capable to handle almost any task with the Application library. Based on the strengths of this library would make it better suited to certain industries than other & vice versa.

Eg: The Power Plant library is not so great thus, to use PCS7 over T3000 on a huge power project is not what Siemens would recommend. Remember the group within Siemens responsible for Power Generation has always made their own CS over the past 25 years and thus know what is required & made the Teleperm family into what it is today. Great for Power Plants not other plants.

Similarly, the group responsible for PCS7 works with all other industrial segments expect power and thus have evolved the SIMATIC family into PCS7 combining the strengths and developing funtionalality of a DCS in the Engineering tools & HMI interface. It is totally different to the SIMATIC PLC tools & HMI.

I also would like to mention today there are only 2 vendors who truly can offer an Integrated Control & Safety System (ICSS), they are ABB (800xA) and Siemens (PCS7). If you need to know more we should start another thread.

So to all out there if you need a new modern furthure proof, cost effective and low spare part inventory system try PCS7.
 
i believe this "real dcs" issue is something made up by vendors and consultants to justify their overrated and overpaid work. this is a discussion from the past. nowadays 50 or 250 mw does not matter, you can do anything with any system. if you need more IO than standard, you may just add another cpu.

boiler and steam controls are one of the most basic algorithms known to industry and almost every vendor will have them as ready packages. furthermore, there will always be a contractor if major revamps or expansions are implemented. i have seen plenty of power plants operating and very seldomly came across plant engineers trying to modify the system all by themselves. there's always specialised DCS subcontractors for these jobs and you don't need to worry about whether the system is "open" or whatever. they will find a way to do the job.

sequence of events logging is another nonsense function, which became fashionable (together with sil-rated designs) in recent years. plant operators are convinced to have this functionality to justify the wasted money on control systems.


as advice for your situation, there's two options:

1. if you're working for the actual plant operator, go for the cheapest solution. avoid the vendors' traps to misguide you towards overspecification of the system. all you need to check is whether you can add/modify/swap components and software on the run. if so, any system will do the job, go for the cheapest.

2. if you're working for the engineering company, produce a material requisition document copied from several sources (must be at least 100 pages and inconsistent within). make sure nobody understands what you're defining, and treat the vendors as if they're making a system totally new for you, rather than a configuration of standard components. also on the client side, prepare another massive document to justify buying the full monty, with analysis of situations which are nonexistent in real life. this way you will have a better impression on the client. they will think you're under the burden of a very difficult engineering work, and selection of a control system is a very complicated task.
 
Dear Dr. R. Murugesan,

Please add the Foxboro I/A Series DCS from Invensys to your list.

I personally headed a team of Engineers in the purchase/configuration/installation/commissioning of a 1 million dollar I/A system back in the nineties.

As the Lead Engineer I made sure that the team had adequate training at Foxboro (6 weeks), coupled with bi-monthly 1 week visits to our site by a Foxboro Engineer to monitor our progress and answer any queries during the 1 year project.

The I/A system is so robust and intuitive that it was a pleasurable task for all of us involved from start to finish (and a successful finish on time too!).

10 Years later I worked in a team of Engineers in the purchase/configuration/installation/commissioning of a medium sized Siemens PCS7 System.

What a difference, someone boobed and assumed that a PCS7 System is just PLC Step7 and SCADA WinCC. IT IS NOT!!!

The two main logic tools used are FBD (Function Block Diagram) and SFC (Sequential Function Chart) which are configured and compiled before being downloaded to the PLCs (or Automation Stations in PCS7 lingo) consequently there was no budget for training.....

To make it worse somebody decided we should use Siemens PDM (Process Device Manager) for the configuration of the hundreds of Profibus PA instruments/valve actuators and Siemens Simocode motor starters on Profibus for motor control, on which we had little experience.

The software configuration was a real battle and a steep learning curve from start to finish (and a finish 12 months+ late!) which left a bitter taste in all of our mouths.

Thankfully the Siemens hardware was excellent (as usual) with only one major module failure (which was in a redundant configuration anyway) during the 2 years we were involved.

I guess I need another PCS7 project to apply all the knowledge gained from the mistakes we made....

Turning to the "is it a DCS" question, PCS7 Version 6.1 had one noticeable deficiency - Inter Automation Station (AS) signals had to be set up manually as there was no tool in FBD or SFC to select a signal from a different AS when configuring. (Unlike the Foxboro I/A System).

However the latest PCS7 system is at Version 7, so hopefully this has been fixed?

Kediri
 
Hello All

I went through all the entries to this question.

None of it is convincing.

You can term any automation solution as a DCS if and only if it satisfies following points, irrespective of the manufacturer:

1. Automation system is distributed in design, meaning to say, no single node on the system is the universal DATA-OWNER. Elaborately, the data on the system is distributed on various nodes, and hence failure of one node will not hamper system operation.

2. Redundancy is a built-in feature of all the data owners on the system.

3. The communications backbone network is deterministic.

4. The tag database is global in nature and can be reference anywhere and everywhere.

5. PLC and DCS are demarketed by a simple thumb rule.... PLCs are PROGRAMMED. DCS controllers CONFIGURED with the built-in tools and as an advancement user defined algorithms can be programmed. Like GE-Fanuc 90-30 or 90-70/Contrologix have their built in algorithm library but again, you need to program them with register assignments for their working. I dont think we have any DCS controller where you need to assign registers and bits for their working. All we do in DCS is configure with right values. It is like FILL IN THE BLANKS of an existing algorithm with meaningful values and assignments.

6. PLCs never have a parameter called OVER-RUNS. Because, PLCs just scan the LD/IL/FLD and the scan time depends on how long these programs are.
While in DCS, it is real-time where the scanning must be completed in a fix scan period, or else overruns of the processors are announced.

There are many other points that can be considered while comparing a DCS and a PLC.

Request the readers to argue and debate on this, if anywhere i am going wrong.
 
The author is purely speaking from his "hear / say" experience it seems. No international Vendor can or will float a product if it is inferior to the standards in market. It is just an added advantage that SIEMENS have gone with uniformity in Hardware for giving better support to industrial community.

Engineers using PCS7 are really delighted by the true DCS experience & options it gives. It is only little tough for a novice to choose a siemens DCS for engineering purposes.

Before using a product none can comment on it. Every international vendor does produce a good product. It is the brand name which sells plus the quality of support they give by services & resellers which decide the favour. Almost all features of a product will be available in another.

Bala
 
T
Experion especially the R400 version is a very open system and truly going to be a DCS. But, having worked in PCS 7 recently and comparing it to Experion I have come to some very interesting conclusions. Ironically to the myth that Honeywell made the first DCS, theirs is really one of the recent OCS. The CEE (Control Execution Environment) is very much similar to a 1990 S5 system. Siemens have had 10 yrs to perfect their OCS architecture, by evolving PCS 7 from S7 controllers.

1. The CM in Experion is said to have been derived from a TDC 2000 Box so that they can be independently loaded and run, the same is in PCS 7 with a chart concept that was mapped to an FC.

2.Online download is possible in both controllers, but separate download and activation of Chart/CM is only possible in Experion.

3. If you have to create a custom block in Experion an engineer will have to actually write it in VB.NET, the same can be accomplished in PCS7 by STL,LAD,FBD or IEC standard SCL.

4. Batch application are relatively easy to engineer on the PCS 7 without the requirement of a Batch Server(Even though they have one) because of the Exquisite 'SFC Type' concept, that has a lot of power, unlike SCM in Experion which I guess is only equal to SFC in PCS 7

5.PCS 7 has very good Asset planning with its Plant Hierarchy, where browsing of charts is possible with respect to area,controller in Plant View and also component view. The Experion asset basically is used only for alarm management from my initial experience.

6.Graphics in PCS 7 are light years better than Experion. The faceplate in PCS 7.1 are all exceptionally operator friendly and readily available to use. Experion graphics suck big time, I think they really need to change/rename PV for solenoid vlave to 'feedback'.

7.Considering foot print of the C300 controller they have really beaten Siemens, but the same design has been maintained for their I/O's that finally give an I/O density for a 2000X1400X600 panel in siemens about 700 while Experion is about 200.

I wouldn't like to be biased, but the facts(almost i hope) are kinda true, considering still i'm still learning, I don't say one is better than the other, I just stated some point I think makes sense for a Commissioning Engineer.
 
Referring to your point about Inter AS communication the latest version of SPPA T3000 or rather all its latest upgrades provide a facility called peer-to-peer connection which one can use for the same
 
i have heard that the latest version of T3000 is being developed to have functionality of both T3000 itself and Tec4FDE
Would you please elaborate on this if you have heard the same?
 
Hi every one

(I am fresher fellow)

I read all the above posts but still i could not conclude the PCS7 is DCS

Now can any one tell me what are the basics requirements for DCS, i mean what are all basic features (For all industrial process domain) one DCS should have to say it as DCS System? like all
above terms used in the posts MTBF, MTBR, Time stamp, Redundancy, reliability etc.

please do not post the generalized answer.
 
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