Technical data

Defining Symbols
8.5 Symbol Table for Shared Symbols
Programming with STEP 7
202 Manual, 05/2010, A5E02789666-01
R/O/M/C/CC Columns
The columns R/O/M/CC show whether a symbol was assigned special object properties
(attributes):
• R (monitoring) means that error definitions for process diagnostics were created for the symbol
with the optional package S7-PDIAG (V5).
• O means that the symbol can be operated and monitored with WinCC.
• M means that a symbol-related message (SCAN) was assigned to the symbol.
• C means that the symbol is assigned communication properties.
• CC means that the symbol can be quickly and directly monitored and controlled in the program
editor ('Control at Contact').
Click on the check box to enable or disable these "special object properties". You can also edit the
"special object properties" via Edit > Special Object Properties menu command
"Symbol" Column
The symbolic name must not be longer than 24 characters.
You cannot assign symbols in the symbol table for addresses in data blocks (DBD, DBW, DBB,
DBX). Their names are assigned in the data block declaration.
For organization blocks (OB) and some system function blocks (SFB) and system functions (SFC),
predefined symbol table entries already exist which you can import into the table when you edit the
symbol table of your S7 program. The import file is stored in the STEP 7 directory under
...\S7data\Symbol\Symbol.sdf.
"Address" Column
An address is the identifier for a particular memory area and memory location.
Example: Input I 12.1
The syntax of the address is checked as it is entered.
"Data Type" Column
You can choose between a number of data types available in STEP 7. The data type field already
contains a default data type that you may change, if necessary. If the change you make is not
suitable for the address or its syntax is incorrect, an error message appears as you exit the field.
"Comment" Column
You can assign comments to all symbols. The combination of brief symbolic names and more
detailed comments makes creating programs more effective and makes your program
documentation more complete. A comment can be up to 80 characters in length.