Contacts

Contacts are graphic components of Ladder Diagram (LD) diagrams used in Function Block Diagram (FBD) programs. Depending on the type of contact, it represents the value or function of an input or internal variable.
Contact types available from the FBD toolbox are:
  • Direct Contact
  • Reverse Contact
  • Pulse Rising Edge Contact
  • Pulse Falling Edge Contact
Change the type of a contact at any time after insertion.
When inserting contacts in program organization units (POUs), assign variables using the
Variable Selector
. Names of assigned variables display above the contact elements within POUs. Replace existing variables by double-clicking the variable names to access the
Variable Selector
or by single-clicking variable names to select from drop-down combo-boxes containing the global and local variables. Also, single-click existing variables, then type literal values in the text boxes provided. When inserting literal values that being with a letter or an underscore, enclose the variable name in single quotes as follows: 'abc'.
  • Select a variable from the drop-down combo-box:
    fbd_var5_TRUSTED
  • Type a literal value in the text box:
    fbd_var6
Task
Procedure
Insert an FBD contact
  1. From the
    Toolbox
    , drag the desired contact type into the language container and place it on the rung.
    The
    Variable Selector
    is displayed.
  2. In the
    Variable Selector
    , select the required variable, then click
    OK
    .
Insert a parallel FBD contact
  1. From the
    Toolbox
    , drag the contact element into the language container while placing it parallel to the existing contact.
  2. Drag the left and right connections to the respective connection points on the rung.
    The required contact is displayed on the parallel branch.
Change the type of a contact in FBD
  • In the language container, select the contact, then select the required type in the
    Modifier
    property of the
    Properties
    window.
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