Finding information about instructions and ladder elements Chapter 1
Rockwell Automation Publication 2080-RM001D-EN-E - February 2015 17
Calling a function
Connected Components Workbench
TM
does not support recursive function calls.
When a function of the Functions section is called by itself or one of its called
functions, a run-time error occurs. Furthermore, functions do not store the local
values of their local variables. Since functions are not instantiated, they cannot call
function blocks.
• A function can be called by a program, by a function, or by a function block.
• Any program of any section can call one or more functions. A function can
have local variables.
• A function has no instance meaning local data is not stored and so is usually
lost from one call to the other.
• Because the execution of a function is driven by its parent program, the
execution of the parent program is suspended until the function ends.
Main program Function Function
Defining function and parameter names
The interface of a function must be explicitly defined with a type and a unique
name for each of its calling (input) parameters or return (output) parameters. A
function has one return parameter. The value of a return parameter for a function
block is different for each programming language (FBD, LD, ST).
Function names and function parameter names can use up to 128 characters.
Function parameter names can begin with a letter or an underscore followed by
letters, numbers, and single underscores.
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