National Instruments NI 5911 Analog Trigger Circuit

Chapter 2 Hardware Overview

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National Instruments Corporation 2-9 NI 5911 User Manual

Figure 2-3. Trigger Sources

Analog Trigger Circuit

The analog trigger on the NI 5911 operates by comparing the current

analog input to an onboard threshold voltage. This threshold voltage,

triggerValue, can be set within the current input range in 170 steps. This

means that for a ±10V input range, the trigger can be set in increments of

20 V/170 = 118m V. There may also be a hysteresisValue associated with

the trigger that can be set in the same size increments. The hysteresisValue

is used to create a trigger window the signal must pass through before the

trigger is accepted. Triggers can be generated on a rising or falling edge

condition as illustrated in the following figures. The four different modes

of operation for the analog trigger are shown in Figures 2-4 to 2-7.

Gain

Analog

Input

High

Level

Low

Level

+

–

COMP

COMP

Analog

Trigger

Circuit

ATC_OUT

a. Analog Trigger Circuit

Trigger

Software

ATC_OUT

RTSI <0..6>

PFI1, PFI2

7

2

Arm

b. Trigger and Arm Sources

CBIHWum.book Page 9 Thursday, October 29, 1998 1:56 PM

Contents

Main Page Important Information Warranty Copyright Trademarks WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS Conventions ! Contents Chapter 1 Taking Measurements with the NI 5911 Chapter 2 Hardware Overview Page Taking Measurements with the NI 5911 Connecting Signals Introduction to the VirtualBench-Scope Soft Front Panel Soft Front Panel Features Page Using the VirtualBench-SCOPE Soft Front Panel Acquiring Data Page National Instruments Corporation 2-1 NI 5911 User Manual Hardware Overview Figure 2-1. NI 5911 Block Diagram Measurement Fundamentals Differential Input Grounding Considerations Input Ranges Input Impedance Input Bias Input Protection AC Coupling Measurement Modes Oscilloscope Mode Flexible Resolution Mode Acquisition System Calibration Internal Calibration External Calibration Triggering and Arming Analog Trigger Circuit Page Trigger Hold-Off Memory Multiple Record Errors During Acquisition RTSI Bus Trigger and Clock Lines PFI Lines PFI Lines as Inputs PFI Lines as Outputs Synchronization A Specifications NI 5911 Acquisition System Page Acquisition Characteristics Accuracy Common-Mode Characteristics Filtering Dynamic Range Noise (excluding input-referred noise) Distortion Timebase System Triggering Systems Acquisition Modes Power Requirements Physical Operating Environment Storage Environment EMC Compliance Calibration Digitizer Basics Understanding Digitizers Nyquist Theorem Analog Bandwidth Sample Rate Vertical Sensitivity ADC Resolution Record Length Triggering Options Making Accurate Measurements Appendix B Digitizer Basics National Instruments Corporation B-5 NI 5911 User Manual Figure B-5. Dynamic Range of an 8-Bit ADC with Three Different Gain Settings Page Page C Customer Communication Electronic Services Bulletin Board Support FTP Support Fax-on-Demand Support Telephone and Fax Support Country Telephone Fax Technical Support Form NI 5911 Hardware and Software Configuration Form National Instruments Products Other Products Documentation Comment Form Title: Edition Date: Part Number: Mail to: Technical Publications Fax to: Technical Publications Glossary Numbers/Symbols A B C D E F G H I M N O P R S T V W Index A B C D E F G H I M N O P R S T V