I want to scan printer IPs in my organization. Is there authentic method? I am using Nmap. I have already checked some commands like: 

1) `nmap -O 10.10x.x.0/24 -oG - | grep printer >> outfile`  

2) `nmap -p 9100,515,631 192.168.1.1/24 -oX printers.xm`

With option 2 I have obtained an xml file, but I don't how to read this file to identify printers because I got many IP's whether they are PCs or printers. 

```
Nmap scan report for 192.168.x.x
Host is up (0.00082s latency).
PORT     STATE    SERVICE
515/tcp  filtered printer
631/tcp  filtered ipp
9100/tcp filtered jetdirect

```

Kindly help me to find out printer IP. I am really messing up. If you want to suggest any command kindly also add some brief instruction for printer IP identification.
One more thing, what is filtered state here?