→Internal variable

An internal variable is a →variable which cannot be used outside of the POU by default.
Related to the ST-syntax, the variables of the section VAR ... END_VAR are usually identified as internal variables. In FBD/LD, these variables are rather identified as →local variables .

In fact, internal variables are:

However due to the rule Assignments from/to local variables of a function block are not allowed outside of function blocks, the variables from section VAR ... END_VAR can be used outside, if these variables have been declared within a →function block .