In the industrial world, digital computers have to be rugged and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices or any activity that requires high-reliabilitycontrol and ease of programming and process fault diagnosis. There are two well-known types of Microcontrollers you should know. The Programmable Logic Controller and the Remote Terminal Unit.
A Programmable Logic Controller (PLC) is basically a gigantic microcontroller. It does the same things a microcontroller can do, but with higher speed, performance, and reliability where a microcontroller is really just a tiny low power CPU or computer with some output registers wired to pins.
A Remote Terminal Unit (RTU) is a microprocessor-controlled electronic device that interfaces objects in the physical world to a distributed control system by transmitting telemetry data to the system and/or altering the state of connected objects based on control messages received from the system.
The Functions of RTUs and PLCs pretty much overlap, but in terms of usage, RTUs tend to be a better fit for wide geographic telemetry, while PLCs are best suited for local area control.