Format a new SD card using SDFormatter

Install NOOBS onto the SD card

Connect Ethernet, HDMI, keyboard, mouse and install Raspbian Lite

Turn on SSH using "sudo raspi-config"

Configure Wi-Fi
http://weworkweplay.com/play/automatically-connect-a-raspberry-pi-to-a-wifi-network/

Now you can optionally disconnect HDMI, keyboard, mouse, and Ethernet, then SSH via the Wi-Fi connection

Install python dev tools
http://raspberry.io/projects/view/reading-and-writing-from-gpio-ports-from-python/

Turn off the serial shell

Enable UART in config.txt

Disable Bluetooth because it conflicts with UART
https://diyin.wordpress.com/2016/05/02/how-to-disable-bluetooth-in-raspberrypi-3/

After reboot the serial connection should be available at /dev/ttyS0 (and not /dev/ttyAMA0)

Connect 4 jumpers from the switch to the adapter using the wiring diagram. Basically 2 and 3 are crossovers, pin 4 on the switch needs 5V input to enable sending status back from the device over RS232. Pin 5 is a common ground.

Connect the RS232-to-TTL adapter to the Raspberry Pi. TX connects to GPIO14 (UART TXD), RX connects to GPIO15 (UART RXD). Connect ground on the Pi to GND and 3.3V on the Pi to VCC.