Z Sensor: Port 0 Explained

Port 0 is an internal sensor that is built into the Z Sensor. This sensor will not be visible outside of the device. This allows the Z Sensor to monitor up to 3 locations with just 1 unit - the internal port as well as the two external ports (Ports 1 and 2). 

Note: This temperature will vary slightly compared to external readings due to being encased inside the device.