To note, on the Raspberry Pi 3 /dev/ttyAMA0 is used by the bluetooth.
Razberry2 board can be found on /dev/ttyS0
To get Razberry2 to work with Raspberry Pi 3:
sudo nano /usr/share/openhab2/runtime/karaf/bin/setenv
-Dgnu.io.rxtx.SerialPorts=/dev/ttyS0:/dev/ttyUSB0"
sudo nano /boot/config.txt
Add to the end:
enable_uart=1
sudo nano /boot/cmdline.txt
Remove everything and add this:
dwc_otg.lpm_enable=0 console=tty1 elevator=deadline net.ifnames=0 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait
Then run these commands:
sudo usermod -a -G dialout openhab
sudo usermod -a -G dialout pi
sudo usermod -a -G dialout root
sudo usermod -a -G tty openhab
sudo usermod -a -G tty pi
sudo usermod -a -G tty root
sudo reboot