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National Instruments Corporation
13
BNC-2121 Connector Accessory for 660X Devices
Miscellaneous Functions
Use these functions with any of the counter applications described in this
document.
Measuring Frequency
To measure a frequency using counter pair 0 and 1, complete the following
steps.
1.
In the C interface or in LabVIEW, select GATE as the output of the
other counter. This selection allows OUT of counter 1 to be the GATE
signal for counter 0.
2.
Connect a wire from the
spring terminal to SOURCE of counter 0,
which is PFI 39. The counter counts the number of edges received
during the interval defined by OUT of counter 1.
The frequency measured is the number of counts divided by the duration of
GATE in seconds. Another counter pair also can be similarly used.
Simultaneously Starting Counters
You can configure two or more counters to arm from the same start
trigger using a software or hardware command. To simultaneously arm two
or more counters to perform single pulse generation, complete the
following steps.
1.
Configure two or more counters to generate a pulse after receiving a
start trigger. In software, select a PFI line, such as PFI 0, to receive the
start trigger.
2.
To see the pulse on the outputs, connect an oscilloscope or analog input
device to OUT of the selected counters.
3.
Connect a wire from the
Trigger
spring terminal to the selected PFI
line and use it to produce the start trigger.
Note
You can use this method for any counter application.
