Checkline DT-311J - Manual (Page 10)

10. ALARMS
1. LOW SPEED INDICATOR (External signal operation only)
Below 180 rpm, the “under” symbol appears.
At degree mode
At rpm mode
2. HIGH SPEED INDICATOR (External signal operation only)
Over 1,550rpm “over” symbol appears.
At degree mode
At rpm mode
If AC power is low, the flashing will stop and “LLLL” will be displayed.
If an alarm symbol appears, (“under”, “over”) the stroboscope flash will
not function.