Product key instructions 1Short press can start the machine. Auto-shutdown function is turned on by default (10 minutes). Auto-shutdown function can be turned on or off by pressing this button. The power icon on the upper left of the screen is turned on or off accordingly. Long press this key, shut down. 2LIGHT 1 > Backlight on/off: Short press to turn on the backlight function, then turn off the backlight. 2 > 650nm light source on/off: long press to the open red light - - then flicker at 1Hz - - then flicker at 2Hz - - then turn off the red light, and cycle in turn. When the red light is turned on, the first line of the screen displays 650 nm. Warning! Do not look directly at the laser light, lest it cause damage to the eyes. 3dB By short pressing this key, the relative optical power test (insertion loss test) or absolute power test can be realized. After entering the relative power test mode, the insertion loss (dB) is displayed at the bottom of the screen, and the reference value is displayed at the second line of the screen. Open RJ45 test mode in 3 seconds, then display RJ45 in the third line, and then exit RJ45 test mode. ( Please note: This product is a simple version, can not test RJ45, if you want to have this function, please contact us.) 4REF Press this key to set the current optical power as a reference value and enter the relative optical power test (insertion loss test) mode. The second line of the display screen will display the set reference value, and the third line will display the relative power value (insertion loss dB). 5 Eight different test wavelengths can be selected, 1310, 1550, 1490, 1625, 1650, 850, 1300 and 980, and the selected test wavelength is displayed on the upper screen.