System flowcharts

Flowcharts are used to design and plan control systems. All flowcharts use the same symbols, linked with arrows to show direction of the flow.

Flowcharts start and end with the oval 'start' and 'end' symbols. Inputs and outputs are shown as parallelograms and processes as rectangles. Sometimes the process box links to a sub-routine [sub-routine: a section of a programme that is not part of the main set of commands. ] - another flowchart with more detailed steps, which then feeds back into the main process. The diamond shape is a "decision box", which checks an input or condition before carrying on.

The diagram below shows the main flowchart symbols and how they are used in a system flowchart.