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Counters
Figure 5-1 shows a counter on the AO Series device.
Counters 0 and 1 each have two inputs (source and gate), one output, and two software registers,
which are used to perform different operations. Counter functionality is built into the DAQ-STC.
For more information on the DAQ-STC, refer to the
System
Overview.
Counter Triggering
Counters support two different triggering actions: start and pause. Only digital triggers can
initiate these actions. For more information on digital triggers, refer to the
Digital Source
section of Chapter 10, Triggering.
Start Trigger
A start trigger begins a finite or continuous pulse generation. When a continuous generation is
initiated, the pulses continue to generate until you stop the operation in software. The specified
number of pulses are generated for finite generations unless the retriggerable attribute is used.
The retriggerable attribute causes the generation to restart on a subsequent start trigger.
Pause Trigger
You can use pause triggers in edge counting and continuous pulse generation applications. For
edge counting acquisitions, the counter stops counting edges while the external trigger signal is
low and resumes when the signal goes high or vice versa. For continuous pulse generations, the
counter stops generating pulses while the external trigger signal is low and resumes when the
signal goes high or vice versa.
Figure 5-1. Counter Block Diagram
Source
Gate
Software Registers
Out
DAQ-STC
section of Chapter 1,
© National Instruments | 5-1
5
DAQ
Triggering with a
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