OM1P and OM2P nodes will work together as long as they are on the same major version of firmware. For example, OM1Ps and OM2Ps both on 4xx-series firmware will work together but one device on firmware 4xx will not communicate with version 3xx. You will need to upgrade your units before adding the new nodes.
To upgrade, uncheck "Disable Automatic Upgrades" and check "NG Firmware." Click "Update Network Settings".
The upgrade process may take several hours depending on the size of your network. For a faster upgrade you can Re-flash the device. Click here for instructions how to do so.