Control Engineering Process Control eNews for July 2002


In this issue:

If Martha Stewart were a controls engineer

I was flipping through TV channels the other day and stumbled on the 'Martha Stewart Living' show.

Martha was preparing a chocolate cake, one of my many weaknesses, so thinking I might find a 'scrumdillyicious' chocolate cake recipe, I paused.

It turns out Martha was following the recipe on the back of the Hershey's Cocoa can. That's the same recipe my grandmother, mother, and wife use. It's the same chocolate cake recipe used by millions of regular, every-day Americans.

For some reason, when I started putting together this month's newsletter, the 60 seconds I spent with Martha Stewart crept back into my mind under the heading of applying 'good engineering practices.'

Okay, so I'm a bit twisted, but when you think about it, Martha Stewart has a staff of hundreds and all sorts of influence. She could have had her staff acquire a chocolate cake recipe from some famous pastry chef, but she didn't. She chose to use a proven, readily available solution from Hershey's.

I'm guessing that if Martha Stewart were a controls engineer, for sure she wouldn't be rich, but she would be seeking, sharing, promoting, and using good engineering practices.

If controls engineer Martha attended a users group meeting, I'm guessing she would come away with a fist full of good engineering practices for things-like alarm management, interlock designs, graphic displays, power and grounding, control system security, control system disaster recovery, and fieldbus segment design-each acquired from fellow attendees.

When Martha got home, she'd share these good engineering practices with her peers. Some of the practices Martha and company might use 'as is,' others they would tweak, but it wouldn't end there. Martha would share those practices with other user group attendees and encourage them to do the same. Martha would also encourage the user group sponsor supplier to make those good engineering practices available to all users. In other words, put that 'chocolate cake recipe' on the product to sell more product!

Last month I ask readers of this e-newsletter two questions:

1. What's your company doing in the way of developing, maintaining, sharing, training in the use of, and enforcing 'good engineering practices' for control, automation, and instrumentation systems?

2. Would you, or someone in your company, be willing to share 'good engineering practices' with others outside your company?

Only five people took the time to respond. Four of those lamented on how bad things were at their company and said they would like to receive 'good engineering practices.' Only one person said they would be willing to share what they had.

That's unfortunate, because in the 1950s, `60s, and `70s the control and instrumentation industry was one of the first places technology found practical uses. This industry was among the pioneers of developing, promoting, using, and sharing 'good engineering practices.'

Perhaps I'm naïve, but I view 'good engineering practices' not as something a company protects in the name of 'competitive advantage,' but something we share with one another to ensure commercial off-the-shelf technology is safely and productively applied to the processes under our stewardship.

In many cases, good engineering practices are the 'common sense' of having been there, done that, and documented what was learned. Good engineering practices are the very things we would share as part of a mentoring process or present in a paper at a conference, seminar, or user group meeting. Good engineering practices are the chocolate cake recipe on the Hershey's Cocoa can.

'Anatomy of Good Engineering Practices'

A good engineering practice solution:

  • Targets a specific industry's problem. The industry can be specialty chemical, semiconductor, food & beverage or it could be control, automation, or instrumentation. The important thing is to identify the boundaries of where the solution has been successfully and repeatedly applied;

  • Defines specific, measurable business requirements the solution solves;

  • Identifies the ways and means used to validate the business requirements (i.e., surveys, studies, interviews, focus groups, etc.);

  • Identifies technologies and/or work practices, standards (local, national, and/or international), procedures, etc. used to assemble the solution;

  • Identifies the measured results that validate the defined problem has improved as a result of the solution;

  • Incorporates the lessons learned while developing and evolving the solution; and

  • Specifies how long the solution has been in use.

Let me try posing the question again, but this time with a specific focus.

1. Is your company applying good engineering practices when it comes to control system security? (...not just prevention of someone getting access to control software, but using some portion of the control system as an entry point to your company's entire business network.)

2. Would you, or someone in your company, be willing to share control system security 'good engineering practices' with others outside your company?

E-mail your response to

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Process control security requirements forum

The Intelligent Systems Division (ISD, Gaithersburg, Md.) of the National Institute of Standards and Technology (NIST, Gaithersburg, Md.) recently established the Process Control Security Requirements Forum (PCSRF), a working group concerned about information security in an increasingly networked world.

The PCSRF working group is made up of users, vendors, and third parties in the process control industry interested in the development and dissemination of process control security standards.

Visit to learn more and register as a participant.

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Top 20 Internet security vulnerabilities

Last October, the SANS (System Administration, Networking, and Security), Institute and the National Infrastructure Protection Center (NIPC, Washington, D.C.) released a descriptive document of the 'Top Twenty Most Critical Internet Security Vulnerabilities.'

SANS and NIPC compiled this list in partnership with computer security experts in academia, industry, and government. (The expert sources are listed at the end of the report.)

The 'Top Twenty...' list is a valuable tool because the majority of successful attacks on computer systems via the Internet can be traced to exploitation of security flaws appearing on this list. Companies can use the list to help prioritize security efforts to close the most dangerous security holes in their computer systems.

View the list via

Additionally, visit the NIPC web site via to read 'Seven Simple Computer Security Tips for Small Business and Home Computer Users.'

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Do you know the answers?

'Learning is not attained by chance, it must be sought with ardor and attended to with diligence.' -Abigail Adams

A few months ago I began introducing a few basic instrumentation and control questions in this newsletter. From the feedback, several find them useful, so here's a few more.

1. In the U.S., all states are regulated by OSHA (Occupational Safety and Health Administration)

a. True
b. False

The answer is: b - False
(Some states have implemented their own safety regulations that are 'tougher' than federal regulations.)

2. On an instrumentation diagram, a diamond represents:

a. Setpoint
b. Control action
c. Power source
d. Interlock

The answer is: b - Control action
(An interlock is one example of control action).

3. The loop identification on an instrumentation diagram:

a. Consists of two, three, or four letters
b. Is the same for all instruments in a specific loop
c. Identifies the measured or initiating variable
d. Appears in the upper portion of the instrument balloon

The answer is: b - Is the same for all instruments in a specific loop.

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FREE - Heat and power calculator from Liebert

For a limited time, Liebert (Columbus, O.) is making available 'Power Calculator,' a slide chart with conversion scales for electric power and heat. The slide chart has been designed to help engineers, plant managers, contractors, and facility managers in determining selection factors for uninterruptible power systems and precision air conditioning.

On the front side of the calculator, set volts vs. amps and directly read single-phase and 3-phase kVA, single-phase and 3-phase kilowatts, or DC kilowatts. Set any two known values (e.g. kVA and nominal voltage) and directly read a third (e.g. amps). Or set kVA and read kW at different power factors.

On the reverse side, convert directly between kilowatts, BTU/hour and tons of cooling. Or set rated kW of a UPS at its efficiency and directly read heat losses in kW, BTU/hour, and tons.

For more information, visit

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Rotary-action valve actuators suit water treatment plants

The U.S. Environmental Protection Agency Safe Drinking Water Act mandates water treatment plants meet turbidity levels of 0.3 Nephelometric Turbidity Unit (NTU) or less. Engineers and plant managers at these plants must scrutinize every element of potable water treatment operations to ensure water leaving the filtering process falls within the mandated turbidity levels.

One of the problems facing water treatment plant personnel is getting older valve actuators to provide precision control valve positioning.

Manufactured by K-Tork (Dallas, Tex.) rotary-action, pneumatic technology meets American Water Works Association standards and provides a simple, accurate and reliable alternative to precisely controlling water treatment plant valves. It helps water-treatment plant staff to better control turbidity levels while reducing downtime and premature backwashes.

For more information, go to

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Eurotherm introduces multi-function I/O module for DAQ applications

Eurotherm's Action Instruments (San Diego, Calif.) recently introduced the I/O Pak IOPK-C112-U Multifunction I/O Module. The Model C112 is a DIN-rail mount I/O module with four universal analog input channels, one analog output channel, and two discrete channels that can be used for either inputs or outputs. The C112's RS-485 serial port may be configured for ACSII, Modbus-RTU, or Profibus-DP communications. The C112's math, logic, control and diagnostic functions, and configurable I/O channels allow the C112 to function as a stand-alone controller or I/O processor, as a remote I/O subsystem for Profibus- or Modbus-based control systems, or as an I/O interface for data acquisition systems.

IOPK-C112-U's analog input channels can be configured to measure any combination of voltage, current, or resistance sensors, with 16-bit resolution and sample rates as fast as 16ms. The analog output channel provides a configurable current output with 14-bit resolution. The output value may be derived locally from a PID (proportional, integral, derivative), from user-defined math functions, or over the network from a 'host' device (i.e., personal computer, programmable logic controller, or operator interface panel). In addition to monitoring on/off status, the discrete input channels provide frequency measurement (up to 25kHz), pulse counting, and quadratured position measurement. The open collector-type discrete outputs may be used for on/off or pulse width modulated control. Control commands may be initiated by a 'host' (PLC/PC) or may be initiated by the C112 itself as an alarm/control function based on a measured or calculated process value.

For more information, visit

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Conferences, seminars, and exhibitions

Control Engineering's website includes registration for nine topical e-mailed newsletters, access to exclusive coverage from Control Engineering Europe , site search, Online Control Engineering Buyer's Guide , and Automation Integrator Guide Online , with advanced search functions. Recently added features include enhanced site search, bookstore, and improved navigation. Go to /

Control Engineering's website also includes links to upcoming conferences, trade shows, and exhibitions:

  • Sep 3-6, Fisher-Rosemount Users Group, San Diego, Calif.

  • Sep 8-12, Invensys Showcase & Users Group, Orlando, Fla.

  • Sep 24-26, Sensors Fall Expo, Boston, Mass.

  • Oct 7-9, ABS Consulting's U.S. Environmental Laws & Regulations Training, Washington, D.C.

  • Oct 8-11, Center for Chemical Process Safety Conference, Jacksonville, Fla.

  • Oct 21-24, ISA Expo, Chicago, Ill.

  • Oct 22-25, ABS Consulting's Clean Water Compliance Institute, Scottsdale, Ariz.

  • Nov 3-8, AIChE Annual Meeting, Indianapolis, Ind.

  • Nov 4-5, ISPE Annual Meeting, Orlando, Fla.

  • Nov 18-24, Embedded Systems, Boston, Mass.

  • Nov 19-23, BIAS, Milan, Italy

  • Nov 20-21, AB Automation Fair, Anaheim, Calif.

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July in Control Engineering

Cover: Embedded control
Along with the need for distributed control (shrinking enclosures, reducing costs, getting control closer to sensors and actuators, reducing wiring, etc.) comes the maturity of embedded control products usually built on 'PC' technology. This article will look at embedded technologies, how major automation companies are exploiting them, and what this means to OEM and end-user engineers who are designing new automation systems.

Frequency domain
The 'frequency domain' is a mathematical construct that simplifies the analysis of feedback control systems. It can be used to show how the closed-loop system will react to a disturbance, a setpoint change, or a change in the behavior of the process. Here's an overview of how frequency-domain analysis works.

Pressure sensing (also in Control Engineering Europe )
Today's pressure transmitters are not your father's pressure-sensing instruments. The article compares and contrasts five essential parameters for pressure transmitters from 1972 to 2002 and explores common instrument practices and opportunities to improve these practices through recent technology enhancements.

Product Focus: Discrete sensors (also in Control Engineering Europe )
Original Control Engineering/Reed Business Research examines trends and user issues with discrete sensors. Recent product descriptions from leading suppliers will be included, along with research results.

Integrator Update
This piece examines challenges and solutions in an application requiring system integration.

Back to Basics: Motion control standards
Most say there is a lack of recognized standards for motion control; a few say there are too many. Here is an overview of the subject and some pointers to what standards are available.

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