ibaMS4xUCO
Manual
Issue 1.5
23
The following scheme shows the period/frequency calculation, when only the positive
edge of the A signal is counted.
A
t
Counter
t
T (1 period)
Figure 9: Theory: period / frequency
Beginning with firmware version 02.12.004, additional measuring parameters can be
configured: minimum measuring time, required periods and timeout.
A
t
Counter
t
T (1 period)
Measuring time 1
Measuring time 2
Timeout 1
Timeout 2
Figure 10: Period / frequency with minimum measuring time and timeout
The minimum measuring time specifies the time period after which the measured fre-
quency value is updated. The frequency measurement starts at the first rising edge and
ends when a rising edge happens after the minimum measuring time has elapsed. Since
several periods may be passed during the measuring time, the frequency is averaged
over the measured periods. In addition, a number of periods can be defined over which
the average is calculated. If the number of required periods has not been reached during
minimum measuring time, then the measuring time is extended until the required number
of periods is reached. This means, both conditions (minimum measuring time and re-
quired periods) have to be met, then the frequency value is updated.
When a timeout is configured, measuring can be interrupted if, for example, a rising edge
cannot be detected during measuring time. The timeout starts with the minimum meas-
uring time, but must be longer than the minimum measuring time. When the measuring
