Hi,
First: you can create an Expression Object called ModbusSlave6 and point it to your expression statement. And then log this Expression Object in the SpreadSheet object.
Second: SpreadSheet object will always add a new row each time. To achieve what you want, you may want to use the DataTable object instead. The DataTable object is like the SpreadSheet object, but much more powerful -- it can do (or can be made to do) everything that the SpreadSheet object does, plus more -- a superset, if you will.
In the DataTable object you can have the cells accumulate values (with some logic) and then write the data to an excel file periodically.
Hope this gives you some ideas.
Best regards,
Khalid 🙂