Instrument off
GX-2009 monitor face
Power Mode Button
Short press: cycle display modes Live → Peak → STEL → TWA → Full Scale (returns to Live after 20 s idle). Hold to power on/off. Short press resets a latching alarm once gas drops below threshold. In Cal/Setup mode: MODE = SELECT / EXECUTE.
Air Button
Hold Air (in fresh air) to perform a fresh-air adjustment. On Peak screen, hold Air to clear peaks. In Cal/Setup mode: AIR = NEXT ITEM / ADJUST VALUE.
Calibration & Setup Modes
Hold AIR, then hold POWER MODE together. Release at the first beep (~1 s) → Calibration Mode (DATE, AIR CAL, AUTO CAL, ONE CAL, BUMP, REFRESH, START). Release at the second beep (~3 s) → User Setup Mode (adds ALARM--P and PASSWORD). STEL/TWA alarms require power-off to clear.