I recently bought a Eaton 5PX1500RTN UPS(1440VA/1440W) with a Network-MS card. I connected it via ethernet and can now see the Web UI for Eaton. This thread here gave me confidence that the UPS would work via the network instead of using the USB or Serial cable/driver. Now comes the part where I configure it with FreeNAS and pfSense router in order for it to gracefully shutdown in case of a power outage...
UPS configuration - master/slave
UPS configuration - master/slave