National Instruments NI 6612 User Manual

3-22 | ni.com
Chapter 3 Counters
Figure 3-23 shows an example of a Pulse-Width measurement using an Arm Start Trigger. Note
that if the counter is armed while the signal-to-measure is already in the active state, the counter
will wait to perform the measurement on the next full pulse after the Arm Start Trigger.
Figure 3-23. Pulse-Width Measurement: Using the Arm Start Trigger
Other Settings
The counter measures the pulse using the Counter Timebase signal. By default, the counter uses
an onboard 100 MHz signal as the timebase. To change the timebase, use the CI.CtrTimebaseSrc
DAQmx Channel property.
You can filter noise on any PFI signal that is an input to the counter by enabling a filter. Refer
to the
PFI Filters section in Chapter 4, PFI, for more information.
If you route the same PFI signal to multiple destinations, you should enable the Synchronization
feature. Refer to Chapter 4,
PFI, for more information.
Two-Edge Separation
In a Two-Edge Separation measurement task, the counter measures the time between two events.
The beginning event is an active edge on a first signal. The ending event is an active edge on a
second signal. Figure 3-24 shows an example of a Two-Edge Separation measurement.
Figure 3-24. Two-Edge Separation Measurement
Counter Timebase
Signal to Measure
Counter Value
Buffer
0
21
DAQmx Start Task
2
21 3
2
3
Arm Start Trigger
First Signal
DAQmx
Start Task
000123 45678
Measured Interval
Second Signal
Counter Timebase
Counter Value
Latched Value
0
8
DAQmx
Read

National Instruments NI 6612 Specifications

General

Brand	National Instruments
Model	NI 6612
Category	Computer Hardware
Language	English