Technical information

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Software

Unity Pro software

Small/Large/Extra Large

DFB user function blocks

With Unity Pro software, users can create their own function blocks for specic

application requirements on Modicon M340, Modicon M580, Premium and Quantum

platforms.

Once created and saved in the library, these user function blocks can be reused as

easily as EFBs (Elementary Function Blocks).

The user function blocks can be used to structure an application. They are used

when a program sequence is repeated several times in the application or for freezing

a standard programming routine. They can be read-only or read/write. They can be

exported to all other Unity Pro applications.

Using a DFB in one or more applications:

b Simplies program design and entry.

b Improves program readability and understanding.

b Facilitates program debugging (variables handled by the DFB are identied in the

data editor).

b Enables the use of private variables specic to the DFBs, which are independent

of the application.

A DFB is set up in several stages:

b The DFB is designed by assigning a name, a set of parameters (inputs, outputs,

public and private internal variables) and a comment to it via the data editor.

b The code is created in one or more sections of the program, with the following

languages selected according to requirements: Structured Text, Instruction List,

Ladder or Function Block Diagram (ST, IL, LD or FBD).

b The DFB can be stored in a library with an associated version number.

b A DFB instance is created in the data editor or when the function is called in the

program editor.

b This instance is used in the program in the same way as an EFB (the instance can

be created from within the program).

Functions (continued)

Selection guide:

page 4/2

Design

Creating the code

Use within the program