Control Engineering's Process Control Newsletter for February 2000
In this issue:
- Fieldbus runs off the track
- OPC unveiled
- New OPC servers available
- Solving continuous pH control problems
- Borrowing technologies from another industry
- Freeware from Intellution
- New Safety System site
- FREE roadmap for designing a safety instrumented system
- Helpful links
- Public service announcement
- About the editor, Dave Harrold
Fieldbus runs off the track
I n the early days of railroads, companies established their own distance between the rails, making it impossible to exchange freight and passenger cars between rail lines without first changing the wheels and axles-a failure to provide interoperability. Apparently Dick Caro, vp of ARC Automation Research (Dedham, Mass.) and Convenor of the International Electrotechnical Commission (IEC) SC65C/WG6 fieldbus committee felt the eight-part, non-compatible IEC 61158 fieldbus standard was becoming similar to the railroad track problems. That's why he recently resigned as committee convenor . I too question the wisdom of the IEC to call a document with multiple non-compatible parts a standard. What's the user community's opinion of what has happened with fieldbus standards? Do standards making organizations delivery meaningful and useful standards; or have these organizations outlived their usefulness? What would be your recommendation to all standards making organizations, especially ISA & IEC, regarding future standards making activities?
I was reading an AMR Research (Boston, Mass.) report written by Kevin Prouty and was surprised, though I probably shouldn't have been, to find not all OPC solutions are being created equal. As I read AMR's report the image of gloves and mittens came to mind.
Object Linking and Embedding (OLE) for Process Control (OPC) is a set of guidelines that describes a standardized manner to use Component Object Model (COM) and Distributed Component Object Model (DCOM) methodologies for automation software components in manufacturing. You might think of OLE, COM, and DCOM as being a hand. Depending on how vendors implement OPC users end up with their hand in a woolen mitten (limited flexibility and usability), or a hand in a surgical glove (greater flexibility and usability).
Mr. Prouty's report explains that companies like Intellution (Norwood, Mass.), Iconics (Foxborough, Mass.), Siemens Energy & Automation (Alpharetta, Ga.), PC Soft (now eMation, Mansfield, Mass.), and Fisher-Rosemount (Austin, Tex.) developed HMI packages using OPC as the foundation for their product-the surgical glove approach; but Mr. Prouty points out, that's not the case for all popular OPC HMI applications.
To ensure users understand if they are buying a mitten or a glove, Mr. Prouty recommends users:
Know the COM-DCOM technology to better understand where vendors are going with OPC. Follow what Microsoft is planning for COM, DCOM, OLE, and OPC;
Choose vendors with a solid track record of migrating with OPC and have a good relationship with Microsoft. Look at the history of the vendor's release of OPC components and how it parallels OPC and COM-DCOM releases;
Use OPC only if you can't get all your components from one vendor. While OPC is a good tool, nothing beats having a vendor that provides all of the needed functions in one package and one UDE (Unified Development Environment);
Evaluate what an OPC component offers versus an extended interface from a vendor. OPC does have a limited set of functions. You may need to use a proprietary interface to get extended functions; and
Evaluate vendors that developed or completely retooled their products to use OPC as a foundation. Be leery of vendors that are just repackaging old applications with OPC as an add-on. Performance issues and outdated architecture are signs that a company is losing focus on its development effort.
For more information, visit www.amrresearch.com or call 617-542-6600.
New OPC servers available
S peaking of OPC, Intellution (Norwood, Mass.) and Matrikon (Edmonton, Alberta, Canada) recently released a number of OPC servers. Intellution now offers Microsoft Windows NT OPC Servers for: Allen Bradley's RSLinx (ABR) 7.2; GE Fanuc 7.10; and Leeds and Northrup (L&N) Max1 7.11. According to Intellution, these releases deliver a number of enhancements; including easier use of ABR's Power Tool utility; enhanced help files; improved performance; support for alarms and events; connectivity to CNC's (Computer Numerical Control), such as lathes and machining centers; and communications with L&N's Max 1 and Max1000 devices.
Matrikon released 50 OPC servers for Microsoft Windows2000, all compliant with the OPC 2.0 specification and backward compatible with the OPC 1.0a specification. Matrikon is also making available five popular OPC servers at no cost to non-production (education and testing) users.
Solving continuous pH control problems
I recently received a new product release from ExperTune (Hubertus, Wis.) promoting a universal pH linearization software solution that works with PID loops. What caught my eye was that ExperTune collaborated with F. G. (Greg) Shinskey, a widely recognized expert in process control and the author of numerous process and advanced process control books and papers, in developing this tool, so I'm pretty confident it works quite well.
Users enter x-y coordinates of titration data into the ExperTune application, it plots a pH curve, converts the curve into a characterizer, and writes the Basic, Fortran, or C++ code that can be applied to the pH loop. If you've been struggling with pH control problems, this is worth a look.
For more information, visit www.expertune.com or call 262-628-0088.
Borrowing technologies from another industry
S ometimes a product developed for another industry could be useful in process control, if only you knew about it. If you've been searching for a miniature solenoid valve that can provide high reliability, low dead-volume, complete isolation between actuator and fluid cavity, and is available in several different plastics, take a look at Burkert Contromatic's (Irvine, Calif.) 6600 series of solenoids designed for use in medical equipment applications.
For more information, visit www.burkert.com or call 949-223-3100.
Freeware from Intellution
I f you are using ActiveX controls, Visual Basic Applications (VBA), etc. to develop control software, a trip to Intellution's freeware site could save you development time. The Intellution site hosts a collection of free software developed and contributed by the Intellution user community. You can help yourself to ActiveX controls, VBA code samples, and other useful tools to help leverage the Intellution Dynamics technology. Just keep in mind, this is 'freeware,' so support is slim at best. The site can be found at www.intellution.com/solutions/freeware .
New Safety System site
C ontrol Engineering has added a new Safety System channel to our Web site at www.controleng.com/ch-process/safety.html . We added this channel anticipating the 4- to 6-fold growth in safety system deployments expected over the next couple of years combined with a recognition that many of those persons who will be responsible for safety system design and application may be looking for help in making informed decisions.
Topics we have planned for this site include:
Do I need a safety-instrumented system (SIS)?
What does safety integrity level (SIL) mean and how do I use it?
What regulations and standards apply to safety instrumented systems?
How can I rank hazardous risk to define SIL's?
What are my safety instrumented system (SIS) options?
Can my SIS and my basic process control system (BPCS) share I/O devices?
Are there any fieldbus's suitable for use with my SIS?
Can my SIS and BPCS share operator interfaces?
How often do I need to test my safety system?
Should I be concerned if my SIS and BPCS are on the same network?
How do safety system devices differ from my other field instrumentation?
If you have safety system related questions, send them to email@example.com and it will be put before our panel of experts.
FREE roadmap for designing a safety instrumented system
M oore Process Automation Solutions (Spring House, Pa.) has produced a 4-color poster providing reference information about the design of a safety-instrumented system (SIS). SISs monitor processes for potentially dangerous conditions and initiate actions to achieve a safer state.
Illustrated with diagrams and charts, the twelve topics include: understanding the safety life cycle; determining the required safety integrity level (SIL); and developing a system architecture. The poster is helpful to anyone involved in developing, implementing, testing, or maintaining an SIS. This non-commercial reference provides detailed information on common safety issues via a step-by-step, visual approach.
For more information, visit www.moore-solutions.com .
Control & Automation Buyer's Guide - Trying to locate a supplier for your control and automation needs? The 1999-2000 Control & Automation Buyers' Guide might be the only stop you need to make.
Automation Integrator Guide - Looking for someone with process control integration experience? The 2000 Control Engineering Automation Integrator Guide provides more than 1,000 listings from integrators all over North America.
Tutorials - Did you know Control Engineering 's Web site host a lot more information than what you find in our monthly magazines? In the process control tutorial section you might find these helpful in making control loops perform better. Some of the Process Control tutorials include:
Process controller tuning guidelines
Turn Problem Loops into Performing Loops
Basics of Proportional-Integral-Derivative Control
Examining the Fundamentals of PID Control
National Manufacturing Week 2000 - Just like the flowers, the conferences and exhibitions begin 'popping up' each spring. The 10th annual National Manufacturing Week Conference and Exhibition is March 13-16, 2000 at McCormick Place in Chicago. Actually this is multiple exhibits under one 600,000-sq. ft. roof. The shows are; National Industrial Automation, National Industrial Enterprise IT, National Plant Engineering MRO & Management, National Design Engineering, plus there is a Motion Hall and a Quality Hall.
Batch process answers - If your process control and automation responsibilities include batch processes and you have a question, you might want to join the electronic World Batch Forum list.
Public service announcement
Y ou can decide if this is a public service announcement or just a painful reminder, but if on April 14th you are working on your 1999 Federal Income Taxes and discover you don't have all the instructions and/or correct forms, click on www.irs.ustreas.gov/prod/forms_pubs/index.html . The 'friendlier' IRS is waiting on you!