Step ladder diagram (SFC) is a graphical language similar to an operational flowchart. When writing programs in SFC, you use graphical components and arrange them to form a set of process plans. The following types of components are available for you to use when creating programs:

Graphic	Name	Description
	Start State	The initial state of the sequential control program, which is only active in the initial state.
	status	A state of the sequential control program that is initially turned off.
	Conditional Transition	When the upper state is active and the transition condition is conductive, the upper state will be turned off and the lower state will be turned on.
	Single Horizontal Line	Horizontal Line connects multiple conditional transitions.。
	Double Horizontal Line	Horizontal Line connects multiple states.。

The program segment is composed of the above elements and represents a complete circuit. At the beginning of PLC operation, the starting state will be activated, and then it will transition downwards to one or more states.