What are "field devices" in control systems?

Field devices in control systems refer to the physical components that are essential for the operation and implementation of control systems. This includes items such as sensors, which gather data about the process being monitored (e.g., temperature, pressure, flow), and actuators, which are responsible for making adjustments to the process (e.g., opening a valve, starting a motor). These devices are situated in the actual environment where the control processes take place, often referred to as "the field."

Their primary function is to interface with the system being controlled, providing real-time data and executing commands. This direct connection to physical processes is crucial for maintaining control system performance and ensuring the desired outcomes. The presence and functionality of field devices greatly influence the precision and reliability of the control system overall, often providing the necessary feedback loop that is essential for process control.