In a Nuclear Power plant, there are a variety of machines performing different specific tasks. One of those is a standalone PID controller having multiple input/output being used in NPP Control is having an inbuilt processor. System control module and multiple communication channels, a floating-point arithmetic unit, multiple Ethernet controllers and also, an Analog Input acquisition module, Digital Input acquisition module, Contact Output Module is to generate contact out being used for annunciation purpose. We have used C programming to write applications, drivers code in a Linux environment. Cross compiler is used for compiling the code. A general purpose PID controller can be used to control a number of different parameters, which can be represented as an Analog Signal. It monitors critical parameters and issues alerts in case of deviant behaviors. Countermeasures can be deployed to take appropriate actions. The uses of such a general purpose PID controller can be extended to various applications in different fields.