→External variable

External →variables within the declaration of a →function block or a →function are needed to access →global variables which were declared within a →program. External variables within the declaration of a program are needed to access global variables which were declared within a →resource (in a PLC-object).
The →data type of an external variable muss match the data type of the global variable.

The ST-syntax for external variables is listed under "Declaration of external variables in ST".
Information on the declaration of variables in →FBD is listed under "Declaring variables in FBD". Information on the declaration of variables in →LD is listed under "Declaring variables in LD and assigning a variable to contact/coil ".