L1 and L2 represent the LEDs on the protection relay's LHMI. When an input is set to TRUE, the corresponding LED is lit. When a function key on LHMI is pressed, the corresponding output, K1 or K2, is set to TRUE.
Note: Function keys in REX610 are designed for a continuous press operation reliably up to 5 seconds. If Function keys are to be used in application for longer than 5 seconds key press, this can be done by using Function keys in conjunction with logic gates, flip-flops, and timer function in the configuration (ACT).