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National Instruments NI cDAQ-9172 Routing AI Reference Trigger Signal to an Output Terminal

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© National Instruments Corporation 23 NI cDAQ-9172 User Guide and Specifications

When the reference trigger occurs, the NI cDAQ-9172 continues to write

samples to the buffer until the buffer contains the number of posttrigger

samples desired. Figure9 shows the final buffer.

Figure 9. Reference Trigger Final Buffer

Using a Digital Source

To use ai/ReferenceTrigger with a digital source, specify a source and an

edge. Either PFI or one of several internal signals on the NI cDAQ-9172

chassis can provide the source. Refer to the Device Routing in MAX topic

in the NI-DAQmx Help or the LabVIEW Help in version 8.0 or later for

more information.

The NI-DAQmx Help is available after installation from Start»

All Programs»National Instruments»NI-DAQ»NI-DAQmx Help.

To vi ew th e LabVIEW Help, in version 8.0 or later, select Help»

Search the LabVIEW Help in LabVIEW. Alternately, to download

the LabVIEW Help, go to ni.com/manuals.

You also can specify whether the measurement acquisition stops on the

rising edge or falling edge of ai/ReferenceTrigger.

Using an Analog Source

Some C Series I/O modules can generate a trigger based on an analog

signal. In NI-DAQmx, this is called the Analog Comparison Event.

When you use an analog trigger source, the acquisition stops on the first

rising or falling edge of the Analog Comparison Event signal, depending

on the trigger properties.

Routing AI Reference Trigger Signal to an Output Terminal

You can route ai/ReferenceTrigger to any output PFI terminal.

Reference Trigger

Pretrigger Samples

Complete Buffer

Posttrigger Samples

Contents

Main USER GUIDE AND SPECIFICATIONS NI cDAQ-9172 DeutschFranais ni.com/manuals Contents Page Page Introduction Safety Guidelines Safety Guidelines for Hazardous Voltages Related Documentation Page Page Device Documentation and Specifications Training Courses Technical Support on the Web Installing the Software National Instruments Corporation 11 NI cDAQ-9172 User Guide and Specifications 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) Mounting the NI cDAQ-9172 NI 9901 Desktop Mounting Kit NI 9910 DIN-Rail Kit NI 9905 Panel Mount Kit Page Setting Up the NI cDAQ-9172 Page Understanding LED Indications Active LED Ready LED Using the NI cDAQ-9172 C Series I/O Modules Correlated vs. Static DIO Modules cDAQ Module Interface USB-STC2 AI and AO Sample Timing Triggering Modes Analog Input Analog Input Triggering AI Start Trigger Signal Routing AI Start Trigger to an Output Terminal AI Reference Trigger Signal Routing AI Reference Trigger Signal to an Output Terminal AI Pause Trigger Signal Analog Input Timing Signals AI Sample Clock Routing AI Sample Clock to an Output Terminal AI Sample Clock Timebase Convert Behavior For Analog Input Modules Scanned Simultaneous Sample-and-Hold Sigma-Delta Slow Sample Rate Modules Getting Started with AI Applications in Software Analog Output Analog Output Data Generation Methods Software-Timed Generations Hardware-Timed Generations Buffered Analog Output Analog Output Triggering Analog Output Timing Signals AO Sample Clock Routing AO Sample Clock to an Output Terminal AO Sample Clock Timebase Signal AO Start Trigger Signal Routing AO Start Trigger Signal to an Output Terminal AO Pause Trigger Signal Minimizing Glitches on the Output Signal Getting Started with AO Applications in Software Digital I/O Correlated vs. Static DIO Modules Static DIO Digital Waveform Acquisition (Correlated Input) DI Sample Clock Signal Using an Internal Source Using an External Source Digital Waveform Generation (Correlated Output) Buffered Digital Waveform Generation Change Detection Event Routing Change Detection Event to an Output Term ina l Change Detection Acquisition Digital Input/Output Configuration for NI 9401 PFI Counters Figure 15. NI cDAQ-9172 Counters Counter Input Applications Counting Edges Single-Point (On-Demand) Edge Counting Buffered (Sample Clock) Edge Counting Controlling the Direction of Counting Pulse-Width Measurement Single Pulse-Width Measurement Buffered Pulse-Width Measurement Period Measurement Single Period Measurement Buffered Period Measurement Semi-Period Measurement Single Semi-Period Measurement Buffered Semi-Period Measurement Frequency Measurement Method 1Measure Low Frequency With One Counter Method 1bMeasure Low Frequency With One Counter (Averaged) Method 2Measure High Frequency With Two Counters Method 3Measure Large Range of Frequencies Using TwoCounters Page Choosing a Method for Measuring Frequency Position Measurement Measurements Using Quadrature Encoders X1 Encoding X2 Encoding X4 Encoding Channel Z Behavior Measurements Using Two Pulse Encoders Two-Signal Edge-Separation Measurement Single Two-Signal Edge-Separation Measurement Buffered Two-Signal Edge-Separation Measurement Counter Output Applications Simple Pulse Generation Single Pulse Generation with Start Trigger Retriggerable Single Pulse Generation Pulse Train Generation Continuous Pulse Train Generation Frequency Generation Using the Frequency Generator Frequency Division Counter Timing Signals Counter n Source Signal Routing a Signal to Counter n Source Routing Counter n Source to an Output Terminal Counter n Gate Signal Routing a Signal to Counter n Gate Routing Counter n Gate to an Output Terminal Counter n Aux Signal Routing a Signal to Counter n Aux Counter n A, Counter n B, and Counter n Z Signals Routing Signals to A, B, and Z Counter Inputs Routing Counter n Z Signal to an Output Terminal Counter n Up_Down Signal Counter n HW Arm Signal Counter n Internal Output and Counter n TC Signals Routing Counter n Internal Output to an Output Terminal Frequency Output Signal Routing Frequency Output to a Terminal Default Counter/Timer Routing Counter Triggering Other Counter Features Cascading Counters Counter Filters Prescaling Duplicate Count Prevention Example Application That Works Correctly (No Duplicate Counting) Example Application That Works Incorrectly (Duplicate Counting) Example Application That Prevents Duplicate Count When To Use Duplicate Count Prevention Enabling Duplicate Count Prevention in NI-DAQmx Synchronization Modes 80 MHz Source Mode Other Internal Source Mode External Source Mode Digital Routing and Clock Generation Clock Routing 80 MHz Timebase 20 MHz Timebase 100 kHz Timebase Specifications Analog Input Analog Output Digital Waveform Characteristics (Slots 1 through 4 Only)1 PFI Characteristics (Slots 5 and 6 Only) General-Purpose Counter/Timers (Slots 5 and 6 Only)1 Frequency Generator (Slots 5 and 6 Only) External Digital Triggers (Slots 5 and 6 or with Some AI Modules) Module I/O States Power Requirements Bus Interface Physical Characteristics Safety Environmental Shock and Vibration Electromagnetic Compatibility CE Compliance RoHS Where to Go for Support