Coils

Coils are graphic components of Ladder Diagram (LD) programs and represent the assignment of Boolean outputs. In an LD program, a coil represents an action. It must be connected on the left to a Boolean symbol, like a contact or the Boolean output of a block.
Types of coils are available from the LD toolbox are:
  • Direct Coil
  • Reverse Coil
  • Pulse Rising Edge Coil
  • Pulse Falling Edge Coil
  • Set Coil
  • Reset Coil
Change the type of a coil at anytime after insertion.
When inserting coils in POUs, assign variables using the Variable Selector. Names of assigned variables display above the coil elements within POUs. Replace existing variables by double-clicking the coil 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 beginning 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:
    ldr_cl1
  • Type a literal value in the text box:
    ldr_cl2
When selecting items like local variables, global variables, and defined words from the drop-down combo-box, typing characters in the text box focuses on the possible items.
While dragging coils from either the toolbox or within a diagram, the language editor displays the possible drop points. Drop points display as plus signs in a black circle. For elements, the possible drop points display on the rung. For instance, since a rung can only have one coil on the right, the editor does not display possibilities when dragging another coil onto the rung. However, if a parallel branch is placed around the coil, the editor displays a possible location for another coil on the branch.
Drop points on a run while dragging elements over the rung:
ldr_dpcl
Task
Procedure
Insert a coil
  1. From the
    Toolbox
    , drag the desired coil type into the language container and place it on the rung where a drop point appears.
    The
    Variable Selector
     appears.
  2. In the
    Variable Selector
    , select the required variable, then click
    OK
    .
    The coil element and its associated variable name appear on the rung.
Insert a parallel coil
  1. From the
    Toolbox
    , drag the branch element onto the existing coil in the language container.
  2. From the
    Toolbox
    , drag the desired coil type onto the branch.
    The
    Variable Selector
     appears.
  3. In the
    Variable Selector
    , select the required variable, then click
    OK
    .
    The coil element and its associated variable name appear on the branch.
Drag a coil
  • To reposition a coil within the diagram, select the coil while holding down the left mouse button, then drag the coil to the required location on a rung where a drop point is displayed.
Change the type of a coil
  • In the language container, select the coil, then press the space bar.
Align all coils in a diagram
  1. Right-click in the language container, then choose
    Properties
    from the contextual menu.
  2. In the
    Properties
    window, set the
    Coil Alignment
     property to True.
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