Ladder diagram value display

This section explains how variable values are displayed in ladder diagram programs for boxed instructions when the controller is offline.

For programs

When there is no initial value for a variable:
  • The default value is displayed in the instruction box and variable grid. For the STRING data type, the default value is empty.
    LD value display - Program - No initial value
    LD value display - Program - No initial value - String
  • You can change the value of the variable in the instruction box or variable grid.
    LD value display - Program - No initial value
    LD value display - Program - No initial value - String
When there is an initial value for a variable:
  • The default value or a previously entered value is displayed in the instruction box or variable grid. For the STRING data type, the default value is empty.
    LD value display - Program - Initial value
    LD value display - Program - Initial value - String
  • You cannot change the value in the instruction box or variable grid. The initial value is displayed in the variable grid.
    LD value display - Program - Initial value - Not editable
    LD value display - Program - Initial value - Not editable - String

For user-defined function block (UDFB) Program Organizational Units (POU)

When there is no initial value for a variable:
  • The value is empty and read-only.
    UDFB POU instruction box
  • The variable grid does not include a
    Value
     column.
    UDFB POU variable grid
When there is an initial value for a variable:
  • The value in the instruction box is empty and read-only.
    UDFB POU instruction box - with initial value
  • The variable grid does not include the
    Value
     column, but a previously entered initial value displays in the
    Initial Value
     column.
    UDFB POU variable grid - with initial value

For user-defined function (UDF) POUs

When there is no initial value for a variable:
  • The value in the instruction box is empty and read-only.
    UDF POU instruction box
  • The variable grid does not include a
    Value
     column.
    UDF POU variable grid
When there is an initial value for a variable:
  • The value in the instruction box is empty and read-only.
    UDF POU instruction box
  • The variable grid does not include the
    Value
     column, but the
    Initial Value
     column displays a previously entered initial value.
    UDF POU variable grid - with initial value

For an instance variable of a function block in a program, UDFB, or UDF

  • The value of the instance is empty for each operand of the function block.
  • After uploading the project, the value of all operands, excluding the instance variable, is empty.
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