Sources:
https://clearcom.com/DownloadCenter/manuals/Arcadia_v1.62/Arcadia_UserGuide-PUB-00021A.pdf
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Note: Arcadia validates firmware versions to internal hardware. In some instances, Arcadia and its components cannot be downgraded. In these instances use a newer firmware version.
HelixNet Upgrade
Upgrades to the HelixNet system are included with the Arcadia software. The HelixNet system requires that all connected devices have the same firmware. Therefore, any mismatches that are detected will cause an immediate and automatic upgrade (or downgrade) to the HelixNet devices on connection. The HelixNet system will also upgrade automatically when the Arcadia Central Station is upgraded.
Note: HelixNet Endpoints manufactured in January 2023 (serial number ends with C00 or higher letter/number) or later can only be used with Arcadia version 2.8 or HMS-4X version 4.4. These endpoints cannot be used with older versions due to differences in hardware components.