Want to get POE to some equipment that doesn’t natively support POE? Don’t worry, it’s easy through the use of commercially available POE splitters that take a POE Ethernet line and split it out into separate standard power and Ethernet data plugs. 5 volt and 12 volt splitters are plenty easy to find. For 9 volt splitters, you’ll find the market to be much more hard-pressed. More typical is “universal” 5 V, 9 V, 12 V splitters, but this equipment much bulkier and simply not as nice as a purpose-built one would be.
There are also POE injectors available for situations where you may only want to run one cable, but don’t have access to a POE switch port.
20190728/https://en.wikipedia.org/wiki/Power_over_Ethernet
This is a useful article about proper grounding for POE equipment. It should not be connected to local ground because it may not be at the same potential as the remote ground, and you can get ground loops. If you want to connect to protective ground, you should do so with an appropriate protective circuit.
20190728/https://electronics.stackexchange.com/questions/222630/grounding-a-poe-powered-device
20190728/DuckDuckGo 5 volt micro-usb poe splitter
20190728/https://www.amazon.com/poe-splitter-micro-usb/s?k=poe+splitter+micro+usb
20190728/DuckDuckGo 12 volt poe splitter
20190728/https://www.amazon.com/PLUSPOE-IEEE802-3af-Splitter-Ethernet-Switches/dp/B075CQD69R
20190728/DuckDuckGo 9 volt poe splitter
Not so successful, but luckily, it looks like step-down 12 V DC to 9 V DC converters are easy to buy on Amazon.
20190728/https://www.amazon.com/Magnolian-Efficiency-Converter-Supply-Waterproof/dp/B00A71E52G/ref=sr_1_3?keywords=12+volt+to+9+volt+converter&qid=1564339891&s=gateway&sr=8-3
Now, let’s see if this nifty gadget is available. 12 volt UPS. There is equipment available, but it is not being sold by Amazon.
20190728/DuckDuckGo 12 volt ups
20190728/DuckDuckGo 12 volt output ups
The name of the game is additional battery power systems for use in taxis and other cars. Yes, so if you want to have a relatively ready-made system to boot, look around for devices built for car power systems.
20190728/https://www.powerstream.com/DC-UPS-1212.htm
20190728/https://www.pimfg.com/product-detail/PIPS-UPS-12V
20190728/DuckDuckGo 12 volt dc ups
20190728/ttps://www.powerinverters.com/