National Instruments Eight-slot USB Chassis NI cDAQ-9172 - Manual (Page 20)

NI cDAQ-9172 User Guide and Specifications 20 ni.com
PFI Signals
The PFI signals, available through correlated digital input and output
modules installed in slots 5 and/or 6, provide access to advanced features
such as triggering, synchronization, and counter/timers. Refer to the
PFI
section for more information.
The PFI pins have a digital filter circuit at the inputs that is configurable on
a per-line basis. The filters allow the rejection of noise caused by noisy
environments, bounces on switches, and so on.
Flexible Counter/Timers
The NI cDAQ-9172 includes two general-purpose 32-bit counter/timers
that can be used to count edges, measure pulse-widths, measure periods and
frequencies, and perform position measurements (encoding). In addition,
the counter/timers can generate pulses, pulse trains, and square waves with
adjustable frequencies. You can access the counter inputs and outputs using
correlated digital I/O modules in slots 5 and/or 6. Refer to the
Counters
section for more information.
Analog Input
To perform analog input measurements, insert a supported analog input
C Series I/O module into any slot on the cDAQ chassis. The measurement
specifications, such as number of channels, channel configuration, sample
rate, and gain, are determined by the type of C Series I/O module used. For
more information and wiring diagrams, refer to the documentation included
with your C Series I/O modules.
The NI cDAQ-9172 has one AI timing engine, which means that only
one analog input task can be running at a time on a chassis. However, the
analog input task can include channels from multiple analog input modules.
Analog Input Triggering
A trigger is a signal that causes an action, such as starting or stopping the
acquisition of data. When you configure a trigger, you must decide how
you want to produce the trigger and the action you want the trigger to cause.
The NI cDAQ-9172 chassis supports internal software, external digital
triggering, and analog triggering.
Three triggers are available: start trigger, reference trigger, and pause
trigger. An analog or digital trigger can initiate these three trigger actions.
Any C Series correlated digital input module can supply a digital trigger
when installed in slots 5 or 6, and some C Series analog modules can supply
an analog or digital trigger in any slot. The start, reference, and pause