Standalone environmental sensors (rack-mount or DIN-rail) almost universally expose SNMP, using either a generic MIB or one specific to the sensor vendor.
Most dedicated environmental sensors ship with SNMP on by default; check the community string is set to something other than the factory default before relying on it.
Generic sensors often support the standard environmental MIB; some vendors (APC's NetBotz line, for instance) use their own. Check the sensor's documentation if Linivo doesn't recognize it as a known profile automatically.
Once polling, set high/low thresholds for temperature and humidity based on your equipment's actual operating range, not a generic default, since a server closet and a purpose-built data hall have very different acceptable bands.