Function Block Diagram (FBD) Editor

The FBD Editor is a graphic tool used to enter and manage function block diagrams according to the IEC 61131-3 standard. (Figure 1)

• The editor supports advanced graphic features such as drag-and-drop, object resizing, and connection line routing features to rapidly and freely arrange the elements of a diagram.
• Insert in an FBD diagram graphic elements of the FFLD (Ladder Diagram) language (e.g., contacts and coils).

Figure 1: FBD main screen

FBD Diagram Components	Related Sections
Call a Function Block FBD Comments FBD Corners FBD Network Breaks FBD Variables LABELS Jumps  JMP  JMPC  JMPNC  JMPCN Use ST Expressions in Graphic Language	Bookmarks Draw FBD Connection Lines FBD Toolbar Insert FBD Objects on a Line Move or Copy FBD Objects Programs: Structure and Syntax Resize FBD Objects Select Function Blocks Select Variables and Instances View FBD Diagrams

FFLD Components

• FFLD Contacts and Coils
• "OR" vertical rail
• Power rails

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• When a contact or a coil is selected, press the Spacebar to change its type (e.g., normal, negated, pulse).

Toggle the Connection to Make it Negative

Boolean connections can be negative at the entry of a block.

1. Select the Boolean connection. ()

   

   Figure 2: Boolean selected connection in FBD program

2. Press the Spacebar (a small circle is displayed)

   

   Figure 3: Toggle Connection in FBD Programs

Display the Execution Order

Data flow is executed from top left to bottom right (CTRL+d shows the execution order).

Figure 4: Execution Order on FBD