Control Engineering hot topics, September 2017

Control Engineering's most clicked articles in September 2017 included stories about PID, ladder logic, differential pressure flowmeters, cloud computing, and process sensors. Miss something? You can catch up here.
By Chris Vavra October 1, 2017

Figure 1: In this example of a well-behaved process, the process variable (green) reacts more-or-less immediately to a step change in the control effort (red). It then rises at an ever-decreasing rate until it reaches a steady-state value. First-order lag processes such as this one—common in temperature, pressure, and flow control applications—are particularly amenable to PID control. Courtesy: Control EngineeringHot topics in Control Engineering, for September 2017, included PID, ladder logic, differential pressure flowmeters, cloud computing, and process sensors. These are based on the top 10 most read articles online in Control Engineering September. Links to each article below.

1. To PID or not to PID

The venerable proportional-integral-derivative (PID) algorithm can solve a variety of feedback control problems, but not all.

2. Ladder Logic: Auto cycles and safety routines

The auto cycle command in ladder logic allows the auto cycle to start in auto mode if no faults are present and for the cycle to stop only when the auto sequence has not been started.

3. Square root scaling for differential pressure flowmeters

The square root for differential pressure-(DP-) based flow can be taken either in the transmitter or in the controller and its easier to configure the transmitter to take the square root because, on the low end, a very small change in DP results in a large change in flow.

4. Ten control system programming best practices

Best practices for programmers include defining their structure, knowing the system resources and tools, consistency, and keeping track of changes during a project.

5. How cloud computing works for industrial processes

Cloud computing can process, filter, and analyze data using an HMI that can then be turned into actionable information for industrial facilities.

6. Choosing sensors for the application: Answers to audience questions

The Control Engineering RCEP webcast, “Choosing sensors for the application,” resulted in more questions than speakers had time to answer in the allotted time. Here each speaker provides more answers.

7. Safety compliance and changing industry practices

To minimize worker injuries and incidents, look at existing workflows to assess the degree of risk and identify areas of concern. Then form specific and targeted interventions that can address these gaps.

8. An integrated network for Industrie 4.0

System integration via the cloud makes networking at the production level easy and secure by vertically integrating management and systems as well as providing a security function for Industrie 4.0.

9. Know when to use open- or closed-loop control

Open-loop controls and closed-loop controls each have unique situations where they are needed and the operator needs to know the setting and the situation before deciding on which one to use.

10. Eight things to avoid in control system automation projects

Identifying missteps such as not building a cross-functional team and not defining responsibilities early in a project can help ensure that a control system automation project is successful.

The list was developed using CFE Media’s web analytics for stories viewed on, September 1-30, for articles published within the last two months.

On Mondays, see the top 5 articles of the prior week. In January, see the hot topics for the prior year.

Chris Vavra, production editor, CFE Media,

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