Hello,
yes, basically you need to check "upplercase/lowercase" first and then input data into the input tables, and make sure the lower/upper case are kept if you reopen the input tables.
also, you do not need to input simsession I suppose, if you have input simversion in gen_params.
I would also suggest you to use SAP standard supported FM BAPI_POSRVAPS_GETLIST3 to achieve similar functionality.
BR,
Ada