Focusing on controller choice, Lean

Many plant-specific factors affect controller criteria, but choices unique to controller type exist as well.

By Jack Smith, CFE Media August 12, 2018

Choosing a controller can be challenging, whether for discrete manufacturing or process industries. While so many plant-specific factors affect controller criteria, choices unique to controller type exist as well.

The author of the cover story explains that matching the capabilities of the controller to the needs of the plant is the place to start. “Breaking down the equipment’s operational needs is a starting point and will help evaluate the range of controllers specified by OEMs or machine builders. Depending on how the equipment fits into the larger manufacturing environment, the automation system can provide a complete solution or just control individual parts.”

In addition, the author explains the capabilities of programmable logic controllers (PLCs) and programmable automation controllers (PACs), remote input/output (I/O) bases communicating via Ethernet and using either a large PLC or multiple smaller connected PLCs.

According to the author, I/O plays a big part in the controller decision. “With some of the system-level items out of the way, defining the I/O count and field device types is next on the list. It is good practice to list all the discrete inputs and outputs on a spreadsheet-and to define each type, such as analog sensor, digital sensor, solenoid, actuator, control valve, and so on. Include the signal type, power requirement, communication protocol, and other considerations.”

Lean manufacturing has focused on eliminating waste since the concept began. Part of eliminating waste is minimizing scrap. The second story in this issue addresses this topic head-on. According to the author, “The cost of scrap is far more than the cost of material itself. Hiding behind every dollar of scrapped inventory are several more dollars lost in storage, productivity, customer satisfaction, and potential revenues.”

Jack Smith, content manager, CFE Media,

This article appears in the Applied Automation supplement for Control Engineering and Plant Engineering.

– See other articles from the supplement below.