Hi @jmcascales ,
Thank you for the clarification! Instead of using an Option list, we would recommend using a Recipe table to achieve the row indexing. It is very similar to a drop down list, but the macro implementation would be less complex than creating a custom indexed Option List using a macro.
The Recipe Table would also make it easier to transfer data from the PLC. The current approach is attempting to read the STRING values directly from the PLC, which is generally only practical if all of the strings are stored within the same array. We would recommend reading the STRING data into HMI local memory addresses first by using a data transfer or a macro, and then linking the Recipe Table to those local addresses.
For more information on how to create a recipe drop-down list, check out this forum post: How to make a recipe drop-down list.