> 3.1 | Format of the Firmware File supplied from Siemens

> For this download solution, the firmware must be available in the format *.USF. Files for each type of module can be requested from Siemens. The firmware file consists of records to be transferred one by one from the host application to the module.
> Figure 6: Format of *.USF firmware file
> Length: The 1st byte of each record is the length byte which specifies the number of data bytes to follow.
> Data: 2nd to nth byte