Ladder Diagram (LAD), Function Block Diagram (FBD) and User-Defined Function (UDF)

LOGO!Soft Comfort provides you with three options of creating circuit programs:

Who will use the ladder diagram (LAD)?

The LAD program editor is suitable for users who are used to working with circuit programs.

Who will use the function block diagram (FBD)?

The FBD program editor is suitable for users who are familiar with the logic boxes of Boolean algebra.

What is the User-Defined Function (UDF)?

UDF is a circuit logic diagram of a group of function blocks, and can be used as a function block in an FBD.

In the following contents, a UDF is called a UDF type, and the copy of a UDF is called a UDF instance. For details, see Using the UDF in an FBD circuit program or another UDF.

Differences between LAD, FBD and UDF in the online help

The online help primarily describes the FBD Editor, because its functionality is closely related to that of the LAD Editor. The UDF is described separately. Where LAD, FBD and UDF differ, the online help describes the differences. The following symbol in the online help indicates the difference in LAD, FBD and UDF functionality:

Converting circuit programs

For information on converting circuit programs, refer to the topics for converting LAD to FBD and from FBD to LAD.

Switching between LAD, FBD, and UDF

You can switch the editor from the Options selection of the Tools menu.