Which of the following devices is used for process automation in industrial systems?

The Programmable Logic Controller (PLC) is specifically designed for process automation in industrial systems. It functions as a robust, specialized computer that accepts inputs from sensors, processes the information based on a pre-written program, and then sends commands to control various machinery and processes. PLCs are integral in a wide range of industrial applications, from manufacturing processes to assembly lines and complex equipment control.

The reliance on PLCs helps ensure efficiency, reliability, and safety in industrial operations by allowing for automation of routine tasks, real-time monitoring, and the ability to respond to various inputs. They are programmed to execute logical operations, facilitate sequencing, and manage timing control, which are essential for automating processes effectively.

Other devices mentioned are relevant in industrial systems but serve different roles. Fieldbus refers to a communication protocol used in automation and control systems to connect various devices, whereas Modbus is a communication protocol commonly used within industrial electronics for transmitting information. Lastly, a workstation computer is typically used for general computing tasks and data analysis, rather than directly controlling industrial processes.