Reader feedback

It’s Not the Years, But the Dollars
I read your editorial, “Reaching the Young Crowd,” (Feb. ’07) and although I don’t disagree with your assertions regarding ISA, I do disagree in part with attracting the “younger people.”

I am an automation/control engineer in my 30s, and I look forward to attending tradeshows. However the problem isn’t so much the desires of younger people as it is the business culture. Fortunately my present company is willing to send me to at least one event a year, but other companies I’ve worked for don’t want to spend the time and money to send staff out of the office. Part of it is the cost of travel; part of it is not wanting to cope with staff being out of the office.

Getting employees out to learn about their trade and upcoming/current technology is a good thing, but first we must convince short-sighted management to commit to it. After that we can work on the “younger people.”

Kris Åkre, U.S. Oil & Refining Co., Tacoma, Wash.

More on Controller Windup
In the Dec. ’06  “Ask the Experts” column, I asked how to “wind up” (my words) a PID controller, so that when I change the controller mode from manual to automatic, the output starts slowly, adjusting from the manual value rather than suddenly changing to “Gain x Error.” Implied in my question was that I wanted to manipulate the integral term while the loop is in manual, so that when I switch to auto, the controller would already have an integral contribution that prevents a “bump” in the output.

In his response, R.H. Meeker pointed out that what he called “initialization” (or “bumpless transfer”) is a standard feature of many controllers. In my case, with Rockwell ControlLogix, with proper configuration, the PID loop’s algorithm adjusts the integral term components, so that the loop won’t bump when switched to auto. This feature is something I immediately used once I realized it existed, and is something anyone designing PID control strategies should understand.

William Love, Kredit Automation & Controls, Phoenix, Ariz.

Open-Source for Process Control?
Off the job, I use Fedora Linux on my personal computer. Fedora is a free operating system with a development community that’s going places with forums and user groups engaged in industrial controls. Using Java development tools, I’m engaged in my own development efforts.

On the job, I am shackled to Microsoft and Rockwell Software’s ridiculously high-priced PLC interfacing software tools.

Your magazine is just another ad avenue for high-dollar vendors and integrators. The real-world development in industrial controls is with the open system community and what can be accomplished without Microsoft. Print some real-world articles.

D. McAnally, Coca-Cola

[Editor’s Reply: If the open source community is as active in process automation as you say, why don’t you or somebody else in the community write an article for Control describing a project done with open source tools? We’d be willing to print one that’s well-written and informative.  --Walt Boyes, Editor in Chief]