PLCgen: IO tests in plcgen-test-models-v33 fails due to allocation of real on the analog IO

This issue is a duplicate of #1062 (closed).

The allocation of a variable with data type real:

input real in_real;  

on the analog input:

%IW6,,in_real 

fails for S7-1500:

Addresses: #798 (comment 2858264), #1062 (comment 2854875), #1019 (closed), #679