Yes, models created in 3.1 should be fully supported when opening them in 3.0. The one exception to this would be a configuration in 3.1 of an Alien RFID reader that does not support LLRP. In 3.1 we added support for the Alien Reader protocol (ARP) to control the RFID Reader, which is not supported in the older version. So, any Alien readers that required ARP would no longer work after the downgrade.
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