Manual
ibaMS4xUCO
24
Issue 1.5
time exceeds the timeout then the frequency w
ill be set to „0“. Measuring starts again
with the next rising edge. The timeout is not active, when it is set to „0“.
With the default settings, measuring is carried out as depicted in Figure 9. Default values
are:
Minimum measuring time = 0 µs
Required periods = 1
Timeout = 0 µs.
In “quadrature mode”, the period is measured between the activated edges. When us-
ing the “quadrature mode”, the measured results need to be converted as follows:
f = f
meas
: 4
T = T
meas
* 4
The measured frequency may be converted into the unit „revolution per minute“ by using
a virtual module, see chapter 11.4.1.
7.4.4.6 Pulse width / duty cycle
When measuring the pulse width, the 50 MHz clock cycles of the internal quartz oscillator
are counted as for the period time. The pulse width
results from the counted 50 MHz
clock cycles multiplied by the quartz cycle time of 20 ns.
The ratio between the pulse width and period time is referred to as duty cycle
D
.
T
D
The following scheme illustrates the used terms.
A
t
T (1 period)
PulseWidth
Counter
t
Figure 11: Theory: pulse width / duty cycle
When a timeout is configured, measuring can be interrupted if a measuring pulse cannot
be detected. When the measuring time exceeds the timeout then the period will be set
to the maximum and pulse and duty cycle will be set to „0“. The timeout is not active,
when it is set to „0“.
