See customer-support/support-documents/software/ for the latest data logger upgrades:
You can upgrade your Ammonit data logger offline using a USB flash drive.
The download links will take you to a zip archive. You need a USB stick with a minimum capacity of 512 MiB. The USB stick must be formatted as FAT32.
Please read the "README.txt" carefully before updating your data logger.
Technical questions? Please contact our support team: firstname.lastname@example.org