Specifications

5.2 Structured Ladder/FBD
5.2.1 Standard format
5-13
5
WRITING PROGRAMS
5.2 Structured Ladder/FBD
The structured ladder/FBD is a graphic language for writing programs using ladder symbols such
as contacts, coils, functions, and function blocks.
5.2.1 Standard format
In the structured ladder/FBD language, units of ladder blocks are used for programming.
For structured ladder, connect the left power rail and ladder symbols with lines.
For FBD, connect the ladder symbols with lines according to the flow of data or signals without
connecting with the left power rail.
Contact Coil
Function
Input variables
Output variables
Function block
Ladder block label
Left power rail