Many types of programmable logic controller are often used in manufacturing, industry and even amusement park rides. The different types can include ladder logic, traditional programming, state logic, human-machine interface, and remote terminal units. Most of these different controllers are defined by the physical configuration of hardware, as well as the types of software or programming languages used. Programmable logic controller hardware is often built to withstand intense weather or physical wear, and software is often made to be somewhat elastic to accommodate many different situations. As a result, the various types of programmable logic controller are often designed for manufacturing and automation systems.
Ladder logic is considered to be one of the most common types of programmable logic controller. In these systems, relay logic hardware is often automated and maintained using programmable logic. This makes ladder logic controllers useful in industrial systems, because many functions can be maintained with minimal human interaction. Additionally, ladder logic might be combined with multiple forms of programmable controllers to create advanced systems.
Traditional programming logic controllers often utilize common computer languages, such as Beginner's All-purpose Symbolic Instruction Code (BASIC), to input commands and maintain a system. These types of programmable logic controller often include some level of human interaction. Logic controllers using traditional programming also might be used to control relay-based systems or factory manufacturing processes that must be flexible.
State logic is often considered to be one of the flexible types of programmable logic controller. By building a computerized model of a real-world task, programmable state logic controllers are often used to assist with tasks that might change quickly. State logic allows for simulation of decision-making, because the state of a program will often change based on input and output data. Many types of programmable logic systems can be modeled using state logic.
Human-machine interfaces often combine the different types of programmable logic controller to allow for automation and routine human interaction. These systems may rely on input commands or provide data to users when requested. This type of programmable controller is often more advanced than fully automated systems, because various programming languages are often needed to facilitate consistent interaction.
Remote terminal units are generally designed to provide a static function. These types of programmable logic controllers, often used remotely, can provide a consistent stream of data despite harsh environmental or data-processing conditions. These systems are often designed to function without much human interaction, which can make them ideal for monitoring when compared to other control systems.
