Unscrew the weatherproof cover and loosen the retainer locking screw. Remove the sensor by pulling straight out (do not twist).
I can provide the exact wiring diagrams or programming steps for your configuration. Xnx Universal Transmitter Quick Start Guide
Turn on the power supply. The display will show the firmware version and then the "Warm-up" screen. Unscrew the weatherproof cover and loosen the retainer
Perform a zero calibration. If using a toxic sensor, perform a span calibration using the appropriate calibration gas. Troubleshooting Common Issues Xnx Universal Transmitter Quick Start Guide
Apply 24V DC power to the unit. The XNX will initiate a self-test routine, which includes: Flashing the diagnostic LEDs. Displaying the internal software version. Testing the LCD backlight. Running a sensor initialization countdown.