Bit Fields tab

A bitfield is a user-defined data type that combines multiple Boolean or integer values into a single variable.

  • Bit Fields are used to define custom variable types and values.
  • A bitfield packs multiple pieces of data together in one variable.
  • Each bit represents an independent piece of information.
    • These bits can be referenced individually within the application.
  • Bitfields provide a compact and organized way to group related status and control flags while maintaining easy access to individual fields.

Adding Bit Fields

A Bit Field is created in one of these ways:

  • Right-click in the Bit Fields tab and select Insert BitFields.
  • Press the Insert key while the Bit Fields tab is active
  • Double-click in the Bit Fields tab.

This creates a default Bit Field labeled as BitFieldn with a Value type INT.

  • The Bit Field type Value is changed by double-clicking on value, allowing a selection from a list.

    • Figure 1:  

Once the Type is defined you may populate the bits.

  • Double click on a bit value to change the text.

  • To save the changes, you must press Enter, Tab, the Up, or the Down arrow key.

Using Bit Fields

This example sets up and tests a Bit Fields entry.

  1. Define the Bit Field Type and Values.
    In this example, the bit is defined as ConveyorState with five values. (Figure 2)
  2. To define a multibit field, select multiple value cells and type the name of the new field.

    3. Figure 2: Example: ConveyorState

    The name of the multibit field appears in all bits the field occupies. (Figure 3)

    Figure 3: Multibit field


      • Not all bits need to be assigned to a field.
      • There may be unassigned bits between fields.
  3. Create a variable whose Type that matches the Bit Field.

    4. In this example, a variable is defined as Converyor1State.

  4. Select the ConveyorState type from the drop-down menu. (Figure 4)

    5. Figure 4: Selected ConveyorState

  5. To use a field, enter the VariableName.FieldName in any editor.
    • In this example, the Structured Text editor is used.
    • Conveyor1State. is entered as the VariableName.
    • When the dot is typed, the user-defined fields dialog box opens. (Figure 5)

    6. Figure 5: Conveyor1State user-defined field dialog box

  6. In the dialog box, select the applicable field for the variable (e.g., PartCount).
  7. Click OK to save the changes or selections and close the dialog box.
  8. To assign or compare the value of a multibit field against a constant, specify the bitfield base type followed by # before the numerical constant.

    9. In this example, since ConveyorState has a base type of SINT, the SINT# prefix is used. (Figure 6)

    Figure 6: Multibit Field Comparison

  9. To assign or compare the value of a field comprising of a single bit, use True, False, 0, or 1.
    Using the base type prefix generates a compiler error. (Figure 7)

    10. Figure 7: Single-bit Assignment

Modbus Support

Bit Fields are supported over Modbus.

  • Figure 8 is a variable with a custom Type defined in the Bit Fields list which is flagged for KVB.
  • It will be exported to Modbus.

Figure 8: Custom Type