You can specify the device address if direct access is used to communicate with the connection device (PLC).
External Device Address
This can be used when the symbol variable is a bit-address or word-address type.
[Symbol Variable] Window
Click the cell in the [Address] column and click 
.
For the variable format, refer to the following.
29.3.2.1 Registering Symbol Variables
For the address format, refer to the following.29.3.3.1 Registering Symbol Variables
When you want to import addresses and comments set up on external equipment, please see the following.
Siemens AG
5.18.7.4 Common Settings - Symbol Variable / Import STEP7 Project File
[Address] Window
Select [Device Address], and in [Type], select [Bit Address (Bit Variable)] or [Word Address (Integer Variable)].
Click the icon to display the [Input Address] dialog box.
In [Device/PLC] (for example, PLC1) and input the address of the model (for example, X00000).
Logic Screen
Double-click the operand and click to display the address input box.
In [Device/PLC] (for example, PLC1) and input the address of the model (for example, X00000).