@andré sorry to be so slow responding. Somehow I missed the post. There are instructions in the data sheet on how to use groups 2 and 3.

As a summary getting the IO to work with Group1 was fairly involved, and given that it is identical across all Neuron devices a function block instance is created and the mappings from registers is done automatically. For groups 2 and 3 you will need to map the IO using standard CODESYS features. To make this simpler, all of the Registers and Coils for these groups are named, there are also function blocks provided that will assist with converting between registers and larger data types.