Siemens Simatic S7 Series System Manual page 106

Programming concepts
5.6 Variable table
Viewing the variable table
To view the variable table for the POU selected in the program editor, select "Variable table"
from the Component drop-down list in the Windows area of the View menu.
Note
You can put the variable table on the quick access toolbar (Page 87) for easy access.
Making assignments in the variable table
Note
Make the assignments in the variable table before using local variables in your program.
When you use symbolic names in your program, the program editor checks first the Local
Variable Table of the appropriate POU, and then the symbol table. If the symbolic name is
undefined in both places, the program editor treats it as an undefined global symbol which is
indicated by a green wavy underline. The program editor does not automatically re-read the
variable table and make corrections to your program logic. If you later make a data type
assignment that defines that symbolic name (in the local variable table), you must manually
insert a pound symbol (#) in front of the name, like this: #UndefinedLocalVar (in the program
logic). For this reason, declaring the variables prior to usage minimizes the programming
effort.
The maximum limit of input/ output parameters for each subroutine call is 16. If you attempt
to download a program that exceeds this limit, STEP 7-Micro/WIN SMART returns an error.
106
System Manual, 09/2015, A5E03822230-AC
S7-200 SMART