When manually adding tags using context menu of the device (or nested group), tags of the required variables are added alternately. If you need to get a list of variables and their addresses, open controller project in GX Works environment. The variables available for polling can be found in Label - Global Label - Global section.
Find desired variable in the table. In this example, MyVar1.
The variable has the following basic parameters: name (any name for ОРС-server), Data Type, memory area where variable is located and Assign Device (number of register of the variable).
In our example MyVar1 variable refers to Real type and is located in D memory area and has 1300 address. Create a tag and select its settings like a variable:
In a same manner you can create tags for other memory areas.
Registers (Word) or bits (Bit) are read depending on the area selected:
For such regions as T (timers) and CNT (counters) three memory types are available - Contact (S), Coil (C) and Current Value (N).
For additional details see Mitsubishi controller setup
For additional details see Importing tags