Chapter 7
Counters
7-30
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waiting for the Gate signal when it is armed. Counter output operations can
use the arm signal in addition to a start trigger.
Software can arm a counter or configure counters to be armed on a
hardware signal. Software calls this hardware signal the Arm Start Trigger.
Internally, software routes the Arm Start Trigger to the Counter
n
HW Arm
input of the counter.
Routing Signals to Counter
n
HW Arm Input
Any of the following signals can be routed to the Counter
n
HW Arm input.
•
RTSI <0..7>
•
Input PFI <0..5>
•
ai/ReferenceTrigger
•
ai/StartTrigger
•
PXI_STAR
Counter 1 Internal Output can be routed to Counter 0 HW Arm. Counter 0
Internal Output can be routed to Counter 1 HW Arm.
Some of these options may not be available in some driver software.
Counter
n
Internal Output and Counter
n
TC Signals
Counter
n
TC is an internal signal that asserts when the counter value is 0.
The Counter
n
Internal Output signal changes in response to Counter
n
TC.
The two software-selectable output options are pulse on TC and toggle
output polarity on TC. The output polarity is software-selectable for both
options.
Routing Counter
n
Internal Output to an Output
Terminal
You can route Counter
n
Internal Output to any output PFI <6..9> or
RTSI <0..7> terminal. All output PFIs are set to high-impedance at startup.
Frequency Output Signal
The Frequency Output (FREQ OUT) signal is the output of the frequency
output generator.