When using a device/PLC address in the logic program, do not mix input and output variables within a word address. As the display unit processes in word units, an unintended value may be written depending on the timing.
You can specify the device address if direct access is used to communicate with the connection device (PLC).
When using a device/PLC address in the logic program, do not mix input and output variables within a word address. As the display unit processes in word units, an unintended value may be written depending on the timing.
See the following for more details on the Direct Access Method. 
2.4.1 Minimizing the Load for Device/PLC Communication (Direct Access)
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.30.3.2.1 Registering Symbol Variables
When you want to import addresses and comments set up on external equipment, please see the following.8.14.5.1 Common Settings (Symbol Variables) - Import STEP7 Project
[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] select the device name (for example, PLC1) and enter the address of the model (for example, X00000).
Logic
Double-click the operand and click to display the address input box.
In [Device/PLC] select the device name (for example, PLC1) and enter the address of the model (for example, X00000).