What are control systems?
A control system makes decisions about how a discrete, continuous, or hybrid processes function, generally ensuring processes operate within appropriate parameters, safely, at an appropriate rate, and within required quality. Control systems help factories and facilities produce quality goods safely and efficiently. Open-loop control is when the output (decision) doesn’t feed back into the control loop. Closed-loop control uses the output to influence, or provide feedback for, the next decision. Control systems can include hardware and software for programmable logic controllers (PLCs), programmable automation controllers (PACs), embedded systems and edge computing, dedicated controls, proportional-integral-derivative (PID) and advanced process controls (APC), along with distributed control systems (DCS), supervisory controls and data acquisition (SCADA), and other controllers, such as industrial PCs (iPCs).
There’s a big difference between a phased process control system migration and just putting delaying the problem of control system obsolescence. Those who don’t plan for distributed control system (DCS) obsolescence will see options narrow.
Nine considerations when selecting a programming language. Ladder logic is favored by manufacturers in discrete industries, but as technology and automation evolve, its usefulness compared to other IEC 61131-3 programming languages and PC programming depends on application complexity and other factors.
Taking accurate, reliable measurements of process parameters that matter is the first step to optimizing any control loop. You cannot improve what you do not measure. Process sensors help, including temperature sensors, pressure sensors, level sensors and flow sensors (flow meters).
While there are many excellent loop tuning methods available, many practitioners prefer tweaking proportional-integral-derivative (PID) tuning constants or using rules-of-thumb rather than doing the required step test and data analysis. But having knowledge about how the individual PID components interact can go a long way to learning proper tuning theory and methods.
Cover Story: Understanding the main types of loads, motors, and applications can help simplify industrial motor and accessory selection.