What Are PLCs?
Traditionally, programmable logic controllers (PLCs) are single-use electronic computing devices that are deployed to manage the operation of machines and electromechanical processes, primarily in an industrial context. Today, manufacturers and other industrial organizations are embracing soft PLCs: software-based controllers that can run on widely available general-purpose PC hardware. Multiple soft PLCs can be hosted on a single device. Both traditional and soft PLCs are commonly used in conjunction with SCADA systems and human-machine interfaces (HMIs).
How PLCs Work
PLCs use the ladder logic programming language to enable engineers to build virtual circuits that can control electromechanical systems. They feature rugged designs that can tolerate harsh conditions and strenuous industrial applications. Because PLCs are often used in time-sensitive applications, they’re capable of scanning inputs and executing programming extremely quickly. Input/output (I/O) connections enable the PLC to receive information from connected equipment and output the appropriate instructions.
PLC Programming Standards
To optimize performance and results as they program PLCs, developers rely on a variety of programming standards. These apply modern software principles to help streamline and simplify the process of designing and operating industrial control systems. While IEC 61131 has long been the industry’s primary standard, many are making or considering a transition to IEC 61449 to maximize IT/OT convergence, especially in multivendor scenarios.
Frequently Asked Questions
PLCs are single-use electronic computing devices that are deployed to manage the operation of machines and electromechanical processes, primarily in an industrial context.
PLCs are often used in industrial applications to control manufacturing equipment, often alongside SCADA systems. They’re also used in nonindustrial use cases such as traffic lights and elevators.
Traditional PLCs are fixed-function appliances that are typically used for a single, specific purpose on the plant floor. Soft PLCs are software-based PLCs that can be run on general-purpose commercial hardware. Multiple soft PLCs can run on a single device.