More and more often there is the need to read or write Excel files with an S7 controller. If you use Siemens products, e.g. WinCC, you can read and write data from CSV files with the help of a self-written VBA script. These files can then be imported into Excel. This is of course very old-fashioned. CSV files were state of the art 20 years ago. Today they are actually only needed for data exchange between different systems, e.g. between a PLC and an ERP system. However, as soon as a human is supposed to use these files, CSV is a bad choice.
Nowadays, customers expect a tidy representation of the values. For this purpose one usually uses the possibilities of a real Excel file (xlsx). Only this way it is possible to create really good looking data documents including logo and formatting. In addition, Excel functions such as charts, formulas or data evaluations can be easily integrated.