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National Instruments Corporation
17
NI myDAQ User Guide and Specifications
Digital I/O (DIO) and Counters/Timers
There are eight, software-timed DIO lines on the NI myDAQ that can be
individually configured for input or output. Additionally, lines DIO <0..4>
can be configured for counter/timer functionality. The input—accessed
through DIO 0, DIO 1, and DIO 2 signals configured as a counter—is used
for counter, timer, pulse width measuring, and quadrature encoding
applications.
When using the counter/timer, the Source is accessed through DIO 0,
the Gate through DIO 1, the Auxiliary Input through DIO 2, the Output
through DIO 3, and the Frequency Output through DIO 4. When using the
counter/timer as a quadrature encoder, A, Z, and B correspond to DIO 0,
DIO 1, and DIO 2, respectively. In some instances, the software may refer
to the output lines as PFI as opposed to DIO. Refer to Table 3 for a list of
the corresponding counter/timer signals assignments through the DIO
terminals.
For more information about event timing requirements, refer to the
section. For more detailed information on using
counter/timers with NI myDAQ, refer to the KnowledgeBase document
How Do I Use the NI myDAQ Counter?
. To access this document, go to
ni.com/info
and enter the Info Code
mydaqcounter
.
Table 3.
NI myDAQ Counter/Timer Signal Assignments
NI myDAQ Signal
Programmable
Function Interface
(PFI)
Counter/Timer
Signal
Quadrature Encoder
Signal
DIO 0
PFI 0
CTR 0 SOURCE
A
DIO 1
PFI 1
CTR 0 GATE
Z
DIO 2
PFI 2
CTR 0 AUX
B
DIO 3
*
PFI 3
CTR 0 OUT
—
DIO 4
PFI 4
FREQ OUT
—
*
Pulse-width modulation (PWM) pulse train measurements are generated through DIO 3
