Call Functions or Function Blocks

When finalized, you can drag-and-drop UDFBs from the library in the (Project) node to a program just like any other function block.

A new instance is automatically created. (Figure 1)

Create an Instance of UDFB in a Program

Figure 1: Create an Instance of UDFB in a Program


    • A single data type parameter defined as IN is passed by the calling program to the UDFB and the body UDFB cannot change its value.
    • A single data type parameter defined as OUT is set in the body UDFB and always actuated in the calling program after the call.
    • A parameter which is an array or a structure is always declared as IN (visible on the left of the block).
    • Both the calling program and the body of the UDFB can read and write such a parameter.

See Also