Introduction to Industrial Automation

Figure 7.5  The SFC program for a two-door security system or a two-mechanism security sys-

tem in the same door.

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  Introduction to Industrial Automation

previous ones. In the following, some general remarks on these languages will be presented from 

a user’s experience point of view:

 

◾

The LAD language is easy to be understand by all and is preferred by engineers for some 

simple applications.

 

◾

Engineers who have some preference in digital logic design, digital electronics, or digital 

circuit design often choose FBD language.

 

◾

For those engineers that do not have the previous experience, it is difficult to choose FBD 

language.

 

◾

A large majority of engineers choose IL language.

 

◾

When the application is complex or contains enumeration, comparisons, and time counting 

functions, then the vast majority of engineers do not choose LAD language.