Not all USB flash drives are compatible with the S331L. Anritsu recommends performing a full FAT 32 long format prior to use with the instrument. Some USB devices may not be recognized even after formatting, in these cases the device must be replaced with another type.
Set the Site Master to save files to an external USB flash drive:
1. Attach the external flash drive and turn on the instrument.
2. Press the File (1) button, then Save.
Choose a Storage Drive
3. Press the Location button then double-tap on the word DRIVE or press the left arrow key until the external USB drive is displayed.
Choose a Storage Drive
4. Double-tap on USB. The Location breadcrumb will change to DRIVE : USB.
5. Press the Set Location submenu key.
The external USB flash drive is now the default location for saving files.