TM5-250_B
10
LP0859X 10/10
RATE DISPLAY OVERFLOW
The rate of the input signal along with the programmed scaling values can cause the
calculated rate display to exceed the meter's 6-digit capacity. If this occurs, the
display will
show
"OLOLOL"
to
indicate an overflow condition.
INPUT FREQUENCY CALCULATION
The meter determines the input frequency by summing the number of falling edges received
during a sample period of time. The sample period begins on the first falling edge. At this falling
edge, the meter starts accumulating time towards Low Update and High Update values. Also,
the meter starts accumulating the number of falling edges. When the time reaches the Low
Update Time value, the meter looks for one more falling edge to end the sample period. If a
falling edge occurs (before the High Update Time value is reached), the Rate display will update
to the new value and the next sample period will start on the same edge. If the High Update
Time value is reached (without receiving a falling edge after reaching Low Update Time), then
the sample period will end but the Rate display will be forced to zero. The High Update Time
value must be greater than the Low Update Time value. Both values must be greater than 0.0.
The input frequency calculated during the sample period, is then shown as a Rate value
determined by either scaling method.
