When installing a new grating in a Princeton Instruments spectrometer, the grating values are saved to the EEPROM of the spectrometer, which is then read by RossApp.
Problem: The new gratings are saved to EEPROM as presets 4,5,6. The original gratings remain in the presets as 1,2,3. Since RossApp only sees the first three presets, the new values will not appear in the Spectrometer Tab dropdown.
Solution: Using the PI software, uninstall the first grating before installing the new one. In the terminal mode of the PI software, the command ?gratings will return which values have been saved to the EEPROM. The first three preset values should now read the newly installed grating.