The black rotary switch is turned clockwise causing the device to power-up and self-check. All yellow LED's illuminate, then blink twice to confirm communication with active detonator receivers (the device is now in "STANBY/READY MODE").
Pressing "ARM ALL" extinguishes the yellow "STANDBY" LED's and illuminates all 8 red "ARMED" LED's. The red LED above "FIRE ALL" begins flashing (the device is now in "ALL-ARMED MODE").
Pressing "FIRE-ALL" causes all 8 "ARMED" LED's flash twice and extinguish ("FIRING COMPLETE").