Accessing Variables in a Function Block from Outside the Function
Block
You can access the input and output variables of a function block from outside the function block. Vari-
ables are written as follows:
InstanceName.VariableName
Example: T
o Access Output Variable B of Function Block Instance FB1_Instance
FB1_Instance
FB1_Instance.B
FB1_Instance.B
FB1
B
You can access the input and output variables for a function block only within the program that con-
tains the function block.
However, you cannot access these variables from within other function block instances even if they
are in the same program. Y
ou cannot access them from other programs.
6-1-6
Details on Functions
You cannot create user-defined functions for Safety Control Units. Only system-defined functions (in-
structions) are allowed.
Structure of Functions
With the FBD language, functions are represented as rectangular boxes as shown below.
A function consists of the following parts.
This function is expressed in the FBD language:
Instruction name
AND
Input parameters
Output parameters
Pa
ra1
Para2
Output1
l
Instruction Name
This is the instruction name.
6 Programming
6 - 10
NX-series Safety Control Unit User's Manual (Z930)