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Large SCADA systems in the USA.
Gauging size of large SCADA application within the USA automation market.
By Rafael N. Jacomino on 9 February, 2007 - 1:06 am

For the sake of application/project metrics, I'd like to hear from anyone that has a SCADA application in the USA similar in scope to the one roughly highlighted below:

* One MS-WIN Server handling ALL SCADA duties (alarming, trending, security, Dbase DAQ/integration, OPC-DA/HAD, peer-2-peer COMMs...). Complemented by three Warm-Standby "twin" servers located in redundant facilities.
* Multiple LANs interconnected with frame-relay combined with several RS-232 Licensed Frequency telemetry links.
* One MS-WIN Network Attached Storage Server used for archiving tasks.
* One MS-WIN Terminal Services Server used by 20 SCADA thin-clients.
* 50 MS-WIN Workstations used as "fat" SCADA clients (PCs & laptops).
* 1165 small PLCs (RTUs) and 64 large PLCs!
* 78k PLC signals/tags & 143k SCADA derived tags!

Our team has done successful proof-of-concept tests, along with multiple full on-line system tests and we are about to go live at the end of February '07. I have "looked" around and barring anything outside the USA, this implementation should be one of the top three centralized SCADA installations of its kind (one server/node). Can you help us confirm this?

By Nathan Boeger on 10 February, 2007 - 3:10 pm

Wow, sounds like quite a project! A few points/questions/observations:

1. Why do you require that one server handle all the SCADA duties with such a large project?

2. The networking requirements shouldn't be a problem for any vendor.

3. The NAS shouldn't be a problem for any vendor.

4. You'll need a beast of a server to host 20 concurrent Terminal Services SCADA clients, particularly if there's much in the way of graphs. There are much better ways of dealing with thin clients. Wonderware does this, but they use "server farms". I'd love to hear people's realistic numbers of Terminal Services clients for a SCADA application.

5. 50 Thick clients would definitely require an efficient distributed SCADA model. Again I question the 1 server model, especially if it's also handling the tasks from #1.

6. That's quite a project - hopefully the vendor has an "unlimited tag count" version.
7. 78k/143k tags, again, quite a project.

If I may ask, who are you considering? What did you use for the proof of concepts? I don't understand what posters could help you confirm without more info. I'm not trying to be a pessimist, but this doesn't strike me as a 2 server project. That said, Inductive Automation software could handle the job, as could other vendor's software. I'm eager to hear comparable end user experiences.

Nathan Boeger
Total SCADA Freedom

By Rafael N. Jacomino on 13 February, 2007 - 1:20 am

Thanks Nathan for the quick input. This SCADA is an upgrade from a VAX/DEC-driven "early generation" SCADA/DCS package. The customer required a similar "one-box" solution. As mentioned in the post, the new WIN-OS SCADA-including the 20-client TSS-are already built and successfully tested with a potential start-up date of 2/21/07. The SCADA itself runs on an HP Proliant ML370 server loaded w/WIN-03 Server, and equipped w/ 4GIGs of RAM and 500GIGs worth of RAID5. The TSS runs on an HP Proliant ML380 server loaded w/WIN-03 ENT Server, and equipped w/ 8GIGs of RAM and 250GIGs worth of RAID5. Nothing very remarkable for the server platforms of today…

We could only fulfill the customer's requirements with the already evaluated, built, and tested system, so I was not really looking for "how-to," but instead "have-you." Mainly because we feel we are treading new SCADA ground. Are there comparable systems out there? Larger, smaller? Even outside of the single server requirement: Any USA "resident" SCADAs with similar tag-counts and client head-counts? If you wish to know the details of the new system, send me an e-mail and I'll give you some specifics.

Rafael N. Jacomino
Sr. Project Engineer
Emerson Process MNGT

By Emmanuel Ecochard on 13 February, 2007 - 11:09 pm

Hi Rafael,

It sounds indeed like quite a project. We don't have this kind of project in the US but I know of similar ones in Europe that use our SCADA software PcVue (including the WebVue solution). Here is an example of one application we did:
- One SCADA station + one redundant SCADA station (the SCADA used is PcVue)
- One archives station with Oracle DB.
- 40 SCADA "thick" client stations (also PcVue).
- One WebVue server station licensed for 30 simultaneous WebVue "Thin" client internet connection.
- 66 PLCs (Schneider Premium)
- 260k tags (I/O and SCADA)

As I said previously, this is one example since we have many different references with such architectures.

In a nutshell, PcVue is a standard SCADA package that can perform all the duties expected from such software. Of course it includes a lot of communication drivers, OPC DA Client and Server connections and supports multi-station architectures so you can use a PcVue as a client of one or several PcVue as servers (with or without redundancy).

The project uses WebVue as thin client: WebVue client is a Java applet that can be use with any Internet browser and that enables you to display and control a PcVue SCADA application (PcVue being setup as a WebVue server) remotely across an Internet/Intranet network. On the client side you don't need to install anything, the Java applet is automatically downloaded at the first connection to the server.

We also have other applications where PcVue is running with Windows Terminal Services (including several thin clients).

Is it the kind of project you expect to compare to yours? If you want more information don't hesitate to ask.


Emmanuel Ecochard
North-America Coordinator
Pcvue, Inc - US subsidiary of ARC Informatique /

By Curt Wuollet on 17 February, 2007 - 2:40 pm

Am I alone when I find it amusing that this system running Windows requires hundreds of times more resources than any VAX provided? :^)


By DAVE FERGUSON on 18 February, 2007 - 2:22 pm

Apparently by the sales volume of Windows PC's, and the complete failure of Microsoft and the fact that Bill is almost bankrupt you ARE alone Curt.

Everyone else must be wrong.....................................and yes, your cheese moved.


By Curt Wuollet on 25 February, 2007 - 10:23 am

Hi Dave
Don't you think it a bit of a paradox that software is the only area of technology where popular expectations for quality and efficiency go steadily _lower_?

Nothing unusual there?



First of all, I spend 90+ Percent of my time in 3 or 4 sectors of software. Rockwell (Clogix), Emerson (DeltaV), Microsoft (All), and some 8-10 off-shoot packages. I have done them all from Siemens, Foxboro, Wonderware, Provox, Intellution and on and on.

I use these TOOLS to do a job. I always look at doing something with the tools rather than make the tools. If the tool that my customers want is Linux, that will be the tool I will use to do the things I do best. Make people money.

But I have very little trouble with the software or hardware as compared to the old days of trouble I had in variants of Unix, CronOs, OS2, CPM, DOS, a PDP, or flipping switches loading binary registers in many of the old platforms.

I know the packages I use fairly well and actually read the manuals and learn to support them and then I do what I do best by adding value with the TOOLS.

Both of my kids are in college and wanted to go into computers, I said to go into solving problems WITH computers, you will be more valuable.

Still a TOOL user and not a TOOL maker (although I have done both). Today MOST of my customers use Microsoft platforms so that is what I use.


By Michael Batchelor on 18 February, 2007 - 2:26 pm

No you aren't, but all the kids in the office look at me like I'm stupid when I wax poetic about supporting 16 users on a box with 9, count 'em - 9, meg of ram.

I can't exactly remember how much RAM the PDP-11/34 had at one place where we used it to run the security system that tracked compartment locations for a thousand badges and controlled about 350 doors. I think it was a 64K, but considering that the whole memory map was limited to 256K, we can assume it was less than that.

I still run several home built routers on 133 mhz pentiums with old ISA clone NE2000 cards, and everyone wants me to replace them with awfully expensive Cisco boxes. Why? It boots from a floppy and just runs for crying out loud. One of them has been there for over 5 years.

Michael R. Batchelor

5 Day Hands on PLC Boot Camp for Allen Bradley
PLC-5, SLC-500, and ControlLogix

Industrial Informatics, Inc.
1013 Bankton Cir., Suite C
Hanahan, SC 29406

843-329-0342 x111 Voice
843-412-2692 Cell
843-329-0343 FAX

By Michael Griffin on 18 February, 2007 - 7:08 pm

In reply to Michael Batchelor: The DEC PDP-8 mini-computer was originally intended for process control applications and originated in discussions between DEC and Foxboro. It was a 12 bit computer with 4k of RAM addressable in 128 byte pages. It sold in what was considered to be very large volumes for its time and was embedded into numerous applications by OEMs. (Source - A
History of Modern Computing - Ceruzzi).

Shoot, Michael, when I started college at Clarkson, the freshmen engineering majors were taught BASIC on a PDP-8 timeshare system! Had a whopping 128KB of memory and each user got a 4KB allocation. Interesting thing was you could really write useful and rather large applications!
Mech.E. Dept. used it for all sorts of design and simulation projects by the professors.

By Curt Wuollet on 25 February, 2007 - 10:25 am

I've got a PDP 11/32 in my basement that's been there for a decade and it's still more reliable than any Windows machine. One marvels at what could be accomplished on the millions of phenomenally powerful PCs extant if they actually used even marginally efficient software. Instead they waste their billions of cycles waiting for a mouse click and painting graphics. Oh, and now they're checking a million times a second what video you might be trying to watch. Now there's innovation for you. We are developing ever more powerful hardware and programming it to be useless.



The PDP-11 series supported up to 2MW (4MB) less the I/O space, which was mapped to the top of the address range. I think the max memory was like 3840KB. (I have the documentation stored away somewhere down here in the cellar...)

Hey, Curt, watch it now! I had my own VAX-11/780 at work, 4MB of memory and a honkin' big (physically) 560MB winchester hard drive that was bigger than a washing machine (RP07 I think). Not to mention a high capacity tape drive (TU78). That was a honkin' machine, and I miss it terribly. (sniff). Also had a PDP-11/44 fully rigged that was the real-time front end. Gawd, how I miss those times.

I wish I had a copy of VAX/VMS and RSX-11M+ to run on one of those freebie simulators, I'd show those script kiddies a thing or two!

By Nik Kinze on 2 March, 2007 - 1:15 am


In the late 70's I worked on SEVERAL 11/08s and 11/780s. The MAXIMUM addressable memory was 1 MB. Most of our machines only had 128K. The cost of the memory alone was astronomical, 8k or RAM (MOS) was almost $500. To get 560 MB of disk space required almost 20 of the half refrigerator sized 30 MB drives, which were $100,000 each. I understand the misplaced decimal points. It happens to us all.


By Rich Wargo on 3 April, 2008 - 11:47 pm


It was an 11/780 with 4MB memory and a single RP07 drive with 560MB. Check your Massbus catalog.

By Curt Wuollet on 6 March, 2007 - 12:09 am

I believe that is possible, but you'd have to dig.
I had to do something similar for a conversion
project years ago. You might find a free clone
if you look hard enough. There are a lot of DEC
fans that are capable of writing such a thing.
And I doubt HP would get too excited if you
can get your PC to read a pack drive or tape.
My 23 is a little too small to run BSD well,
but the emulators have plenty of horsepower.



By Nikolas Kinze on 19 February, 2007 - 10:43 pm

While working for a large intercontinental metals company from 1999-2003, I completed the aggregation of a SCADA system similar to yours in scope with the exception of the 100+ RTUs. On this system there were over 200 PLCs. Most were at our location, however, we had several in other locations, national and international. I believe the tag count was close to that of yours within 2%. In addition to the PLCs connected, there were a couple of dozen MODCOMPs, each with 30-40 Modbus ports connected to the SCADA system via either MB+ bridges or ethernet bridges. I guess if you added up the MODCOMP ports and called them RTUs, it would equal to about 2/3 of your 1165 small PLCs.

While most of this was done in pieces, it was still an extremely large undertaking. Especially the control of data to and from the MODCOMPS.

By Rafael N. Jacomino on 24 February, 2007 - 9:11 pm

With the 8-bit 4-octet addresing scheme of ModBus Plus, I bet you had a challenge keeping the network bridging "sane." Three questions:
1. What is MODCOMPs? Do you mean Modicon PLCs?
2. Is this SCADA application in the USA?
3. Did the SCADA run in one Server?

Rafael N. Jacomino

Goodness! I haven't heard of MODCOMP in years! They were a computer company that originally sold to NASA (they were based in Florida), then marketed to the industrial market. Their big selling point was having multiple register sets so their context switches were REALLY fast (like <10 microsecond to switch between processes). It was a 16-bit machine, standard software (OS, Fortran) The DFW airport used them to control their automated transport system. I knew a couple of the guys that did most of the work on that.

By Nik Kinze on 2 March, 2007 - 1:28 am

The MODCOMPs' claim to fame was the fast instruction execution and the incredible interrupt processor. They were designed by AEG, the same company that ended up owning Modicon for a while in the 80s and 90s. Chemical plants were the most common place to see them. Union Carbide developed a system modification that made them popular.


By Peter Clout on 4 March, 2007 - 3:49 pm

There are so many posts and threads on Windows vrs. Linux vrs VMS on VAX/Alpha/Itanium. Vsystem has, I know, a 120,000 tag system on an aluminum mill with sub-second scan times. This is run with one Alpha running VMS. The size posts do not mention the scan times as it is here that efficiency comes in.

When choosing a popular operating system, remember that in any system, decision have to be made at the design phase and the choices tend to be influenced by the major market. Windows was never designed, as far as I can see, to be a fully protected operating system, MS is working towards that kludge by kludge. That is fine and acceptable for many applications where 7/24 is not an issue but ask the people who had a MS glitch pump sewage down the street or a virus that shut down a plant for 2 days.

We support all the principle operating systems since our customer's priorities differ.


Peter Clout
Vista Control Systems, Inc.
176 Central Park Square
Los Alamos, NM 87544-4031
(505) 662-2484 FAX
(505) 662-3956 Cell
(505) 450-7810