National Instruments cDAQ-9172 User manual

USER GUIDE AND SPECIFICATIONS

NI cDAQ-9172

Contents

Introduction............................................................................................. 4

Safety Guidelines .................................................................................... 5

Safety Guidelines for Hazardous Voltages...................................... 5

Related Documentation........................................................................... 6

Device Documentation and Specifications ...................................... 9

Training Courses.............................................................................. 9

Technical Support on the Web......................................................... 9

Installing the Software ............................................................................ 10

Installing NI-DAQmx ...................................................................... 10

Installing Other Software................................................................. 10

Installing the NI cDAQ-9172.................................................................. 11

Mounting the NI cDAQ-9172.......................................................... 12

NI 9901 Desktop Mounting Kit................................................ 12

NI 9910 DIN-Rail Kit............................................................... 13

NI 9905 Panel Mount Kit ......................................................... 13

Setting Up the NI cDAQ-9172................................................................ 15

Understanding LED Indications.............................................................. 17

Active LED ...................................................................................... 17

Ready LED ...................................................................................... 17

Using the NI cDAQ-9172 ....................................................................... 18

C Series I/O Modules....................................................................... 18

Correlated vs. Static DIO Modules........................................... 19

cDAQ Module Interface .................................................................. 19

USB-STC2 ....................................................................................... 19

AI and AO Sample Timing....................................................... 19

Triggering Modes ..................................................................... 19

Independent Data Streams ........................................................ 19

PFI Signals................................................................................ 20

Flexible Counter/Timers........................................................... 20

ni.com/manuals

DeutschFrançais

NI cDAQ-9172 User Guide and Specifications 2 ni.com

Analog Input ............................................................................................20

Analog Input Triggering...................................................................20

AI Start Trigger Signal..............................................................21

AI Reference Trigger Signal .....................................................22

AI Pause Trigger Signal ............................................................24

Analog Input Timing Signals ...........................................................24

AI Sample Clock .......................................................................24

AI Sample Clock Timebase.......................................................25

Convert Behavior For Analog Input Modules...........................25

Getting Started with AI Applications in Software ...........................28

Analog Output .........................................................................................28

Analog Output Data Generation Methods........................................28

Software-Timed Generations ....................................................29

Hardware-Timed Generations ...................................................29

Analog Output Triggering ................................................................30

Analog Output Timing Signals.........................................................31

AO Sample Clock......................................................................31

AO Start Trigger Signal ............................................................31

AO Pause Trigger Signal...........................................................33

Minimizing Glitches on the Output Signal.......................................34

Getting Started with AO Applications in Software..........................34

Digital I/O................................................................................................35

Correlated vs. Static DIO Modules ..................................................35

Static DIO.........................................................................................36

Digital Waveform Acquisition (Correlated Input) ...........................36

DI Sample Clock Signal............................................................36

Digital Waveform Generation (Correlated Output) .........................37

Buffered Digital Waveform Generation....................................38

Change Detection Event ...................................................................39

Routing Change Detection Event to an Output Terminal .........39

Change Detection Acquisition..........................................................39

Digital Input/Output Configuration for NI 9401 ..............................39

PFI ...........................................................................................................40

Counters...................................................................................................40

Counter Input Applications ..............................................................42

Counting Edges .........................................................................42

Pulse-Width Measurement ........................................................44

Period Measurement..................................................................46

Semi-Period Measurement ........................................................48

Frequency Measurement ...........................................................49

Position Measurement ...............................................................54

Two-Signal Edge-Separation Measurement..............................57

Counter Output Applications............................................................59

Simple Pulse Generation ...........................................................59

Pulse Train Generation..............................................................61

Frequency Generation ...............................................................62

Frequency Division ...................................................................63

Counter Timing Signals................................................................... 63

Counter n Source Signal ........................................................... 64

Counter n Gate Signal............................................................... 65

Counter n Aux Signal ............................................................... 65

Counter n A, Counter n B, and Counter n Z Signals ................ 66

Counter n Up_Down Signal ..................................................... 66

Counter n HW Arm Signal ....................................................... 66

Counter n Internal Output and Counter n TC Signals .............. 67

Frequency Output Signal .......................................................... 67

Default Counter/Timer Routing....................................................... 68

Counter Triggering .......................................................................... 68

Other Counter Features.................................................................... 69

Cascading Counters .................................................................. 69

Counter Filters .......................................................................... 69

Prescaling.................................................................................. 70

Duplicate Count Prevention...................................................... 71

Synchronization Modes ............................................................ 73

Digital Routing and Clock Generation.................................................... 75

Clock Routing .................................................................................. 76

80 MHz Timebase .................................................................... 76

20 MHz Timebase .................................................................... 76

100 kHz Timebase .................................................................... 76

Specifications .......................................................................................... 77

Analog Input .................................................................................... 77

Analog Output.................................................................................. 77

Digital Waveform Characteristics (Slots 1 through 4 Only) ........... 78

PFI Characteristics (Slots 5 and 6 Only) ......................................... 78

General-Purpose Counter/Timers (Slots 5 and 6 Only)................... 79

Frequency Generator (Slots 5 and 6 Only) ...................................... 80

External Digital Triggers (Slots 5 and 6 or with Some

AI Modules) .................................................................................. 80

Module I/O States ............................................................................ 80

Power Requirements ........................................................................ 80

Bus Interface .................................................................................... 81

Physical Characteristics ................................................................... 81

Safety ............................................................................................... 81

Environmental.................................................................................. 82

Shock and Vibration ........................................................................ 82

Electromagnetic Compatibility ........................................................ 83

CE Compliance ................................................................................ 83

Environmental Management............................................................ 83

Where to Go for Support......................................................................... 84

NI cDAQ-9172 User Guide and Specifications 4 ni.com

Introduction

This user guide describes how to use the National Instruments cDAQ-9172

chassis and lists specifications. For an interactive demonstration of how to

install the NI cDAQ-9172, go to

ni.com/info and enter daqinstall.

The NI cDAQ-9172 is an eight-slot USB chassis designed for use

with C Series I/O modules. The NI cDAQ-9172 chassis is capable of

measuring a broad range of analog and digital I/O signals and sensors using

a Hi-Speed USB 2.0 interface. For module specifications, refer to the

documentation included with your C Series I/O module(s) or go to

ni.com/manuals.

Figure 1. NI cDAQ-9172 Chassis

1 Power Switch

2 Ready/Active LEDs

3 Power Connector

4 USB Connector

5 Empty Module Slots

6 Installed C Series I/O Modules

7 Screw for Ground Connection

NI cDAQ-9172

Ready

Active

11-30 VDC

15 W

OFF

ON

12345

1

2

3

4 5 6

7

Safety Guidelines

Operate the NI cDAQ-9172 chassis only as described in this user guide.

Note Because some C Series I/O modules may have more stringent certification standards

than the NI cDAQ-9172 chassis, the combined system may be limited by individual

component restrictions. Refer to the Using the NI cDAQ-9172 section of this document for

more details.

Caution The NI cDAQ-9172 chassis is not certified for use in hazardous locations.

Hot Surface This icon denotes that the component may be hot. Touching this component

may result in bodily injury.

Safety Guidelines for Hazardous Voltages

If hazardous voltages are connected to the module, take the following

precautions. A hazardous voltage is a voltage greater than 42.4 V

pk

or

60 VDC to earth ground.

Caution Ensure that hazardous voltage wiring is performed only by qualified personnel

adhering to local electrical standards.

Caution Do not mix hazardous voltage circuits and human-accessible circuits on the same

module.

Caution Make sure that chassis and circuits connected to the module are properly

insulated from human contact.

Caution The NI cDAQ-9172 chassis provides no isolation, but some modules offer

isolation. Follow the safety guidelines for each module when using hazardous voltage.

NI cDAQ-9172 User Guide and Specifications 6 ni.com

Related Documentation

Each application software package and driver includes information about

writing applications for taking measurements and controlling measurement

devices. Check

ni.com/manuals for the most recent hardware

documentation, and refer to Table 1 for a list of locations for driver and

application software documentation. The following document location

references assume you have NI-DAQmx 8.8 or later, and where applicable,

version 7.1 or later of the NI application software.

Table 1. NI Driver and Application Software Documentation

Software Document/Description Location/Topic

NI-DAQmx for Windows DAQ Getting Started

Guide—describes how to

install and use the

NI-DAQmx driver software

for Windows and your data

acquisition (DAQ) device,

how to confirm the device is

operating properly, and how

to take an NI-DAQmx

measurement.

Start»Programs»

National Instruments»

NI-DAQ»DAQ Getting Started

Guide

NI-DAQ Readme—includes

information about

NI-DAQmx and Traditional

NI-DAQ (Legacy).

Describes how to choose

the API to use, new

features, and a list of known

issues, supported devices,

and devices not supported.

Also provides details about

system requirements.

Start»Programs»

National Instruments»

NI-DAQ»NI-DAQ Readme

NI-DAQmx Help—explains

how to get started in your

OS and ADE; provides an

NI-DAQmx overview;

includes information about

programming the most

common measurement

tasks with references to

examples in CVI/C, C++,

.NET.

Start»Programs»

National Instruments»

NI-DAQ»NI-DAQmx Help

LabVIEW Getting Started with

LabVIEW—describes the

LabVIEW graphical

programming environment

and the basic LabVIEW

features you use to build

data acquisition and

instrument control

application.

Start»All Programs»

National Instruments»

LabVIEW»LabVIEW Manuals or

navigate to the

labview\manuals

directory and opening

LV_Getting_Started.pdf

LabVIEW Help—provides

information about

LabVIEW programming

concepts, step-by-step

instructions for using

LabVIEW, and reference

information about

LabVIEW VIs, functions,

palettes, menus, and tools.

Help»Search the LabVIEW Help

LabVIEW Help Topics Specific to NI-DAQmx

Includes overview

information and a tutorial to

learn how to take an

NI-DAQmx measurement

in LabVIEW using the

DAQ Assistant.

From the Contents tab, Getting

Started»Getting Started with DAQ

Describes the LabVIEW

NI-DAQmx VIs and

properties.

From the Contents tab, VI and

Function Reference»

Measurement I/O VIs and

Functions

Contains the conceptual

and how-to information you

need to acquire and analyze

measurement data in

LabVIEW, including

common measurements,

measurement

fundamentals, NI-DAQmx

key concepts, and device

considerations.

From the Contents tab, Taking

Measurements

Table 1. NI Driver and Application Software Documentation (Continued)

Software Document/Description Location/Topic

NI cDAQ-9172 User Guide and Specifications 8 ni.com

LabWindows

™

/CVI

™

LabWindows/CVI Help

Data Acquisition

book—contains

NI-DAQmx measurement

concepts and step-by-step

instructions about creating

a measurement task using

the DAQ Assistant.

Help»Contents, then select Using

LabWindows/CVI»

Data Acquisition»Taking an

NI-DAQmx Measurement in

LabWindows/CVI

LabWindows/CVI Help

NI-DAQmx Library

book—contains

NI-DAQmx API overviews

and function reference.

LibraryReference»

NI-DAQmx Library

Measurement

Studio/Microsoft Visual

Studio .NET

Microsoft Visual Studio

.NET Help/NI

Measurement Studio

Help—contains

NI-DAQmx methods and

properties.

Measurement Studio»

NI Measurement Studio Help and

select NI-DAQmx .NET Class

Library or NI-DAQmx Visual C++

Class Library

ANSI C without

NI Application Software

NI-DAQmx Help Start»All Programs»

National Instruments»

NI-DAQ»NI-DAQmx Help

NI-DAQmx C Reference

Help—describes the

NI-DAQmx Library

functions.

Start»All Programs»

National Instruments»

NI-DAQ»NI-DAQmx C Reference

Help

Table 1. NI Driver and Application Software Documentation (Continued)

Software Document/Description Location/Topic

Device Documentation and Specifications

Check ni.com/manuals for the most recent device and software

documentation. If you do not have Web access, NI-DAQmx includes a

Documentation CD that includes documentation available when

NI-DAQmx released.

Training Courses

If you need more help getting started developing an application with

NI products, NI offers training courses. To enroll in a course or obtain

a detailed course outline, refer to

ni.com/training.

Technical Support on the Web

For additional support, refer to ni.com/support or zone.ni.com.

.NET Languages without

NI Application Software

*

NI-DAQmx .NET

Help—contains conceptual

topics for using NI-DAQmx

with Visual C# and Visual

Basic .NET.

Start»All Programs»

National Instruments»

NI-DAQ»NI-DAQmx .NET

Reference Help. Expand

NI Measurement Studio Help»

NI Measurement Studio .NET

Class Library»Reference to view

the function reference. Expand

NI Measurement Studio Help»

NI Measurement Studio .NET

Class Library»Using the

Measurement Studio .NET Class

Libraries

Visual Studio .NET

Help—contains conceptual

topics for using NI-DAQmx

with Visual C# and Visual

Basic .NET.

Help»Contents. Select

Measurement Studio from the

Filtered By drop-down list and

follow the location instructions for

the NI-DAQmx .NET Help.

*

With the Microsoft .NET Framework version 1.1 or later, you can use NI-DAQmx to create applications using Visual C#

and Visual Basic .NET without Measurement Studio. You need Microsoft Visual Studio .NET 2003 or Microsoft Visual

Studio 2005 for the API documentation to be installed.

Table 1. NI Driver and Application Software Documentation (Continued)

Software Document/Description Location/Topic

NI cDAQ-9172 User Guide and Specifications 10 ni.com

Installing the Software

Installing NI-DAQmx

The DAQ Getting Started Guide, which you can download at ni.com/

manuals

, offers NI-DAQmx users step-by-step instructions for installing

software and hardware, configuring channels and tasks, and getting started

developing an application.

Installing Other Software

If you are using other software, refer to the installation instructions that

accompany your software.

Installing the NI cDAQ-9172

Figure 2 shows the dimensions of the NI cDAQ-9172 chassis.

Figure 2. NI cDAQ-9172 with Dimensions in Millimeters (Inches)

53.8 mm

(2.12 in.)

46.0 mm

(1.81 in.)

23.7 mm

(0.94 in.)

20.3 mm

(0.80 in.)

25.0 mm

(0.98 in.)

44.1 mm

(1.74 in.)

24.8 mm

(0.98 in.)

23.2 mm

(0.91 in.)

19.1 mm

(0.75 in.)

31.7 mm

(1.25 in.)

58.9 mm

(2.32 in.)

44.1 mm

(1.74 in.)

63.1 mm

(2.49 in.)

36.4 mm

(1.43 in.)

51.7 mm

(2.04 in.)

165.1 mm

(6.50 in.)

59.6 mm

(2.35 in.)

88.1 mm

(3.50 in.)

254.0 mm

(10.00 in.)

NI cDAQ-9172

11-30 VDC

15 W

ON

OFF

Active

8 7 6 5 4 3 2 1

Ready

19.0 mm

(0.75 in.)

4.10 mm

(0.16 in.)

NI cDAQ-9172 User Guide and Specifications 12 ni.com

Mounting the NI cDAQ-9172

You can mount the NI cDAQ-9172 chassis using a desktop, a 35 mm

DIN-Rail, or a panel mount accessory kit. For accessory ordering

information, refer to

ni.com.

Caution Your installation must meet the following requirements:

• Allows 25.4 mm (1 in.) of clearance above and below the NI cDAQ-9172 chassis for

air circulation.

• Allows at least 50.8 mm (2 in.) of clearance in front of the modules for common

connector cabling such as the 10-terminal detachable screw terminal connector and, as

needed, up to 88.9 mm (3.5 in.) of clearance in front of the modules for other types of

cabling. For more information about mechanical dimensions, refer to

ni.com/

info

and enter the info code cDAQMechanical. For more information about cable

dimensions, refer to

ni.com/info and enter the info code cDAQCable.

NI 9901 Desktop Mounting Kit

The NI 9901 Desktop Mounting Kit includes two metal feet you can install

on the sides of the NI cDAQ-9172 chassis for desktop use. With this kit,

you can tilt the NI cDAQ-9172 chassis for convenient access to the I/O

module connectors. When you install the two metal feet, the two existing

screws on the power switch side of the chassis must be removed. After

removing the screws, replace them with the two longer screws included in

the NI 9901 Desktop Mounting Kit.

Figure 3. NI 9901 Desktop Mounting Kit

NI 9910 DIN-Rail Kit

The NI 9910 DIN-Rail Kit contains one clip for mounting the chassis on a

standard 35 mm DIN-Rail. To mount the chassis on a DIN-Rail, fasten the

DIN-Rail clip to the chassis using a number 2 Phillips screwdriver and

two M4 × 17 screws. The screws are included in the DIN-Rail kit. Make

sure the DIN-Rail kit is installed as illustrated in Figure 4, with the larger

lip of the DIN-RAIL positioned up. When the DIN-Rail kit is properly

installed, the NI cDAQ-9172 chassis is centered on the DIN-Rail.

Caution Remove the I/O modules before removing the chassis from the DIN-Rail.

Figure 4. DIN-Rail Installation on the NI cDAQ-9172

NI 9905 Panel Mount Kit

To mount the chassis on a panel, align the chassis on the panel mount

accessory. Attach the chassis to the panel mount kit using two M4 × 17

screws (as shown in Figure 5). National Instruments provides these screws

with the panel mount kit. You must use these screws because they are the

correct depth and thread for the panel. These slots in the panel mount kit

NI cDAQ-9172 User Guide and Specifications 14 ni.com

can be used with M4, M5, No. 8, or No.10 panhead screws. Figure 5

illustrates the panel dimensions and installation on the NI cDAQ-9172

chassis. Refer to the documentation included with the NI 9905 Panel

Mount Kit for more detailed dimensions.

Figure 5. Panel Mount Dimensions and Installation on the NI cDAQ-9172

NATIONAL

INSTRUMENTS

NI cDAQ-9172

11-30 VDC

15 W

ON

OFF

Active

87654321

Ready

330.2 mm

(13.00 in.)

88.1 mm

(3.47 in.)

28.1 mm

(1.11 in.)

48.1 mm

(1.90 in.)

Setting Up the NI cDAQ-9172

Complete the following steps to prepare the NI cDAQ-9172 chassis for use:

1. Before connecting the hardware, install the NI-DAQmx software.

Refer to the DAQ Getting Started Guide for more information about

software installation.

Note The NI-DAQmx software is included on the CD shipped with your kit and is

available for download at

ni.com/support. The DAQ Getting Started Guide is available

after installation from Start»All Programs»National Instruments»NI-DAQ»DAQ

Getting Started Guide. Other NI documentation is available from

ni.com/manuals.

2. If you are not using any mounting accessories, attach the provided

rubber standoffs to the back of the NI cDAQ-9172 chassis.

3. Make sure the NI cDAQ-9172 chassis power switch is turned off.

4. Attach a ring lug to a 14 AWG (1.6 mm) wire. Connect the ring lug to

the ground terminal on the side of the chassis using the ground screw.

Attach the other end of the wire to the system safety ground.

Figure 6. Ring Lug Attached to Ground Terminal

Note

Additionally, attach a wire with a ring lug to all other C Series I/O module cable

shields. You must connect this wire to the ground terminal of the chassis using the ground

screw.

5. Remove the plastic cover from the connector in any empty module slot.

1 Attached to System Ground

1

NI cDAQ-9172 User Guide and Specifications 16 ni.com

6. Squeeze both C Series I/O module latches, insert the I/O module into

the module slot, and press until both latches lock the module in place.

7. Connect the NI cDAQ-9172 chassis with the supplied USB cable to

any available USB port on your computer.

8. Connect the power source to the NI cDAQ-9172 chassis. The

NI cDAQ-9172 chassis requires an external power supply that meets

the specifications in the Power Requirements section.

Note The NI cDAQ-9172 chassis uses a DC input jack with a locking ring. Use only this

connector with the NI cDAQ-9172 chassis. Refer to the Specifications section for more

information about the connector.

9. Secure the power supply and USB cables, as depicted in Figure 7,

using the two tie wraps and adhesive tie wrap mounts included in the

shipping kit. The tie wraps and adhesive mounts help secure the

non-latching USB connection. They can also be used to route the

cables to a desirable position.

Figure 7. cDAQ Chassis With Secured Cables

10. Power on the NI cDAQ-9172 chassis.

11. Double-click the Measurement & Automation icon, shown at left,

on the desktop to open MAX.

12. Expand Devices and Interfaces, and then expand NI-DAQmx

Devices.

NI cDAQ-9172

13. Check that your device appears under Devices and Interfaces. If your

device does not appear, press <F5> to refresh the view in MAX. If your

device is still not recognized, refer to

ni.com/support/install for

troubleshooting information.

14. Right-click your device and select Self-Test.

If you need help during the self-test, select Help»Help Topics»

NI-DAQmx and click MAX Help for NI-DAQmx.

When the self-test finishes, a message indicates successful verification

or an error. If an error occurs, refer to

ni.com/support/install

for troubleshooting information.

Note When in use, the NI cDAQ-9172 chassis may become warm to the touch. This is

normal.

Understanding LED Indications

Active LED

The Active LED indicates whether the NI cDAQ-9172 chassis is

communicating over the USB bus.

Ready LED

The Ready LED is lit when the NI cDAQ-9172 chassis is ready for use. The

color indicates whether the USB connection is Full-Speed or Hi-Speed.

Table 2. Active LED

LED Definition

Amber Power is applied, but USB connection is not

established

Green USB traffic present

Off No USB traffic present

Table 3. Ready LED

LED Definition

Amber Hi-Speed (480 Mbit/sec)

Green Full-Speed (12 Mbit/sec)

Off USB connection is not established

NI cDAQ-9172 User Guide and Specifications 18 ni.com

Using the NI cDAQ-9172

The cDAQ system consists of three parts: C Series I/O modules, the cDAQ

module interface, and the USB-STC2. These components digitize signals,

perform D/A conversions to generate analog output signals, measure and

control digital I/O signals, and provide signal conditioning.

Figure 8. NI cDAQ-9172 Block Diagram

C Series I/O Modules

National Instruments C Series I/O modules provide built-in signal

conditioning and screw terminal, spring terminal, BNC, D-SUB, or

RJ-50 connectors. A wide variety of I/O types are available, allowing

you to customize the cDAQ system to meet your application needs.

C Series I/O modules are hot-swappable and automatically detected by the

NI cDAQ-9172 chassis. I/O channels are accessible using the NI-DAQmx

driver software.

Because the modules contain built-in signal conditioning for extended

voltage ranges or industrial signal types, you can usually make your

wiring connections directly from the C Series I/O modules to your

sensors/actuators. In most cases, the C Series I/O modules provide isolation

from channel-to-earth ground.

For more information about which C Series I/O modules are compatible

with the NI cDAQ-9172 chassis, refer to the KnowledgeBase document,

C Series Modules Supported in the NI cDAQ-9172 CompactDAQ.

C Series

I/O Module

C Series

I/O Module

C Series

I/O Module

cDAQ Module

Interface

USB-

STC2

USB

2.0

To access this KnowledgeBase, go to ni.com/info and enter the info

code

rdcdaq.

Correlated vs. Static DIO Modules

Digital I/O module capabilities are determined by the type of digital signals

that the module is capable of measuring or generating. Static digital I/O

modules are designed for signals that change slowly and are accessed by

software-timed reads and writes. Correlated digital I/O modules are for

signals that change rapidly and are updated by either software-timed or

hardware-timed reads and writes. For more information about Digital I/O

modules, refer to the Digital I/O section.

cDAQ Module Interface

The cDAQ Module Interface manages data transfers between the

USB-STC2 and the C Series I/O modules. The interface also handles

autodetection, signal routing, and synchronization.

USB-STC2

The USB-STC2 features independent high-speed data streams; flexible

AI and AO sample timing; triggering; PFI signals for multi-device

synchronization; flexible counter/timers with hardware gating; digital

waveform acquisition and generation; and static DIO.

AI and AO Sample Timing

The USB-STC2 contains advanced analog input and analog output timing

engines. A wide range of timing and synchronization signals are available

through the PFI lines. Refer to the Analog Input Timing Signals and

Analog Output Timing Signals sections for more information about the

configuration of these signals.

Triggering Modes

The NI cDAQ-9172 supports different trigger modes, such as start trigger,

reference trigger, and pause trigger with analog, digital, or software

sources. Refer to the Analog Input Triggering and Analog Output

Triggering sections for more information.

Independent Data Streams

The NI cDAQ-9172 supports four independent high-speed data streams;

allowing for up to four simultaneous hardware timed tasks, such as analog

input, analog output, buffered counter/timers, and correlated digital

input/output.

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

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