Properties of an FBD program
Properties of an FBD program:
FBD sections have a grid behind them.
A grid section consists of ten grid units. A grid unit is the smallest possible space between two objects in an FBD section.
An FBD section can be configured in number of cells (horizontal grid coordinates and vertical grid coordinates).
The FBD programming language is not cell oriented but the objects are still aligned with the grid units.
The execution order is determined by the position of the FFBs in the section (executed from left to right and from top to bottom). If the FFBs are connected to a network using graphical links, the execution order is determined by the signal flow, see also section Execution order of the FFBs in the Reference manual.
The execution order can be influenced in several ways, see also section Changing the execution order in the Reference manual.
A syntax and semantics check is performed immediately after the statement is entered. The result of this check is displayed in colored text and objects.
Syntactically or semantically incorrect sections can be saved.
FBD program objects
The objects of the programming language FBD (Function Block Diagram) help to divide a section into a number of:
EFs and EFBs (Elementary Functions and Elementary Function Blocks),
DFBs (Derived Function Blocks) and
These objects, combined under the name FFBs, can be linked with each other by:
Comments for the logic of the program can be added using text objects.
Edit and view functions
Edit and view functions of the FBD Editor:
Moving objects (also between different FBD/LD sections)
Using bookmarks
Searching and replacing variables and function blocks and DFB instances.
Input assistants
Input assistants for the FBD Editor:
Function input assistants for functions, function blocks and procedures
Online functions
Online functions of the FBD Editor:
Display the current value.
Setting breakpoints
Setting watchpoints