ISPSoft User Manual 11.1 Introduction of Function Block Diagrams 11.1.1 Knowing Function Block Diagrams A function block diagram is one of the five languages defined by IEC 61131-3 standard. A function block diagram and a ladder diagram are graphical programming languages. A ladder diagram is a programming language that represents a program by a graphical diagram based on the circuit diagrams of relay logic hardware. A function block diagram is a block diagram that describes a function between input variables and output variables. A program is systematically divided into several function blocks, and these function blocks are arranged in a function block diagram.
A function block diagram in ISPSoft is shown below. 11.1.2 Editing Environment Select the Function Block Diagram (FBD) option button in the Language section in the Create Program window. Please refer to section 5.4.1 for more information. 11-2