Technical data

Defining Symbols
8.6 Entering Shared Symbols
Programming with STEP 7
Manual, 05/2010, A5E02789666-01 205
8.6 Entering Shared Symbols
There are three methods of entering symbols that can be used for programming at a later stage:
• Via Dialog Box
You can open a dialog box in the window where you are entering a program and define a new
symbol or redefine an existing symbol. This procedure is recommended for defining individual
symbols, for example, if you realize that a symbol is missing or you want to correct one while
you are writing the program. This saves you displaying the whole symbol table.
• Directly in the Symbol Table
You can enter symbols and their absolute addresses directly in a symbol table. This procedure
is recommended if you want to enter a number of symbols and for when you create the symbol
table for a project because you have the symbols which were already assigned displayed on
the screen, making it easier to keep an overview of the symbols.
• Import Symbol Tables from Other Table Editors
You can create the data for the symbol table in any table editor you are comfortable with (for
example, Microsoft Excel) and then import the file you created into the symbol table.
8.6.1 General Tips on Entering Symbols
To enter new symbols in the symbol table, position the cursor in the first empty row of the table and
fill out the cells. You can insert new rows before the current row in the symbol table using the menu
command Insert > Symbol. If the row before the cursor position already contains an address, you
will be supported when inserting new symbols by a presetting of the "Address" and "Data Type"
columns. The address is derived from the previous row; the default data type is entered as data
type.
You can copy and modify existing entries using the commands in the Edit menu. Save and then
close the symbol table. You can also save symbols which have not been completely defined.
When you enter the symbols, you should note the following points:
Column Note
Symbol The name must be unique within the whole symbol table. When you confirm the entry in this
field or exit the field, a non-unique symbol is marked. The symbol can contain up to 24
characters. Quotation marks (") are not permitted.
Address When you confirm the entry in this field or exit the field, a check is made as to whether the
address entered is allowed.
Data Type When you enter the address, this field is automatically assigned a default data type. If you
change this default, the program checks whether the new data type matches the address.
Comment You can enter comments here to briefly explain the functions of the symbols (max. 80
characters). Entering a comment is optional.