You do not manually create your own tags for I/O data.
That is done automatically for you when you put the I/O module into the configuration.
There are 2 tags created for an Input Module. By example, if I assign an Input Module to Slot 2 in the same chassis as the controller, the tags created are:-
Local:2:I - data Input to the controller from the Input module
Local:2:C - configuration data downloaded to the module
Part of (repeat, part of) the Local:2:I tag that is created, is a 32-bit DINT (called .Data) which contains the data from the I/O points on the module. Yes, it is a 32-bit DINT, so that it can handle a 32-point module, but if it is a 16-bit module, only the first 16-bits in .Data are used.
Simple now...
IN-0 on your Input module appears in the controller database as Local:2:I.Data.0
IN-13 on your Input module appears in the controller database as Local:2:I.Data.13