NI cDAQ-9178/9174 User Guide and Specifications 32 ni.com
PFI
You can configure channels of a hardware-timed digital module as Programmable Function Interface
(PFI) terminals. Hardware-timed digital modules can be installed in up to two chassis slots. The
NI cDAQ-9178 chassis also provides two terminals for PFI.
You can configure each PFI individually as the following:
• Timing input signal for AI, AO, DI, DO, or counter/timer functions
• Timing output signal from AI, AO, DI, DO, or counter/timer functions
Counters
The NI cDAQ-9178/9174 has four general-purpose 32-bit counter/timers and one frequency generator.
The general-purpose counter/timers can be used for many measurement and pulse generation
applications. Figure 20 shows the NI cDAQ-9178/9174 Counter 0 and the frequency generator. All
four counters on the NI cDAQ-9178/9174 are identical.
Figure 20. NI cDAQ-9178/9174 Counter 0 and Frequency Generator
Counters have eight input signals, although in most applications only a few inputs are used.
For information about connecting counter signals, refer to the Default Counter/Timer Routing section.
Each counter has a FIFO that can be used for buffered acquisition and generation. Each counter also
contains an embedded counter (Embedded Ctrn) for use in what are traditionally two-counter
measurements and generations. The embedded counters cannot be programmed independent of the main
counter; signals from the embedded counters are not routable.
Counter Timing Engine
Unlike analog input, analog output, digital input, and digital output, NI cDAQ-9178/9174 counters do
not have the ability to divide down a timebase to produce an internal counter sample clock. For sample
Counter 0
Counter 0 Source (Counter 0 Timebase)
Counter 0 Aux
Counter 0 HW Arm
Counter 0 A
Counter 0 B (Counter 0 Up_Down)
Counter 0 Z
Counter 0 Gate
Counter 0 Internal Output
Counter 0 TC
Input Selection Muxes
Frequency Generator
Frequency Output Timebase
Freq Out
Input Selection Muxes
Embedded Ctr0
FIFO
Counter 0 Sample Clock
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