States and modes of a system are concepts used to describe the behavior and condition of a system.
The distinction between states and modes is that states describe the condition of a system, while modes describe its behavior. For example, a car's state might be "driving", while its mode might be "normal operation" or "emergency mode".
A state is a description of the condition of a system at a particular point in time. For example, the state of a car might be "driving", "stopped", or "parked". States are often used to describe the status of a system or its components, such as powered on or powered off.
They can therefore be thought of as conditions that are external to the systems control.
As another example, if the system of interest is a solar panel then possible states would be:
Additionally there may be more states that the system can be in at the same time, such as:
A mode is a description of the behavior of a system in response to certain conditions or inputs. Modes describe how a system operates under different conditions, such as normal operation, emergency mode, or maintenance mode.
It's important to understand the states and modes of a system in order to design it in a way that meets its requirements. The states and modes of a system can affect its behavior, reliability, and performance, so it's important to carefully consider them during the design process.