one button test function

test instrument self-diagnostic function direct from Wanlin Fire Protection — 12-year factory experience, WL-ST600 smoke detector tester certified CE/UL 268A/EN 54/NFPA 72/BS 5839/AS 1851. Key specs: Rechargeable Aerosol Dispenser + Precision Heat Element + NIST Calibration + Digital Display, USB-C Charging + LCD Display + Calibration Certificate + Data Sto···