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National Instruments 1141, 1142, 1143, SCXI Figure 4-1. SCXI-1141/1142/1143 Module Block Diagram

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Chapter 4 Theory of Operation

SCXI-1141/1142/1143 User Manual 4-2 ni.com

Figure 4-1. SCXI-1141/1142/1143 Module Block Diagram

External Clock

Analog Bus

Rear Signal Connector

Analog

Switch

Analog

Switch

Digital

Interface

and Control

Filter

Input

Protection

Front Signal Connector

SCXIbus Connector

Calibration

Selection

–

Instrumentation

Amplifier

Instrumentation

Amplifier

Filter

Bypass

Input

Protection

Calibration

Selection

Calibration

EEPROM

–

Output Clock

AI 0

AI 7

AI 0+

AI 0–

AI 7+

AI 7–

Digital Control Bus

Internal

16-Pin Analog

Input Connector

8 to 1 Multiplexer

Filter Filter

Bypass

AI 0

AI 7

Contents

Main Page Important Information Warranty Copyright Trademarks Patents Conventions Contents Chapter 1 About the SCXI-1141/1142/1143 Chapter 2 Connecting Signals Chapter 3 Configuring and Testing Chapter 4 Theory of Operation Chapter 5 Using the SCXI-1141/1142/1143 Module Appendix A Specifications Page Tables About the SCXI-1141/1142/1143 What You Need to Get Started National Instruments Documentation Installing Application Software, NI-DAQmx, and the DAQ Device Installing the SCXI-1141/1142/1143 into an SCXI Chassis or a PXI/SCXI Combination Chassis Installing the Terminal Block Verifying the SCXI-1141/1142/1143 Installation in Software Installing SCXI Chassis and Modules in Software Troubleshooting the Self-Test Verification Troubleshooting in NI-DAQmx Page Connecting Signals Front Connector Table 2-1. Front Signal Pin Assignments Front Connector Signal Descriptions Analog Input Channels Page Page Digital Input and Output Page Table 2-2. Rear Signal Pin Assignments Page Page Analog Output Signal Connections Digital I/O Signal Connections Page Configuring and Testing SCXI-1141/1142/1143 Software-Configurable Settings Common Software-Configurable Settings Gain/Input Range Input Selection Configurable Settings in MAX NI-DAQmx Creating a Global Channel or Task Verifying the Signal Verifying the Signal in NI-DAQmx Using a Task or Global Channel Page Theory of Operation Power-Up State Chapter 4 Theory of Operation Figure 4-1. SCXI-1141/1142/1143 Module Block Diagram SCXI-1141/1142/1143 User Manual 4-2 ni.com 8 to 1 Multiplexer Digital Control Circuitry Input Amplifiers Correcting Gain and Offset Errors Lowpass Filters Filter Theory Performance of the SCXI-1141/1142/1143 Module Filters Magnitude Response Page Phase Response Page Page Setting the Cutoff Frequency Using the SCXI-1141/1142/1143 Module as an Antialiasing Filter Page Using the External Clock Input DC-Correction Circuitry and Overload Recovery Filter Bypass Mode Rear Connector Analog Outputs Multiplexed Mode (Recommended) Parallel Mode Using the SCXI-1141/1142/1143 Module Developing Your Application in NI-DAQmx Typical Program Flowchart Figure 5-1. Typical Program Flowchart for Voltage Measurement Channels General Discussion of Typical Flowchart Creating a Task Using DAQ Assistant or Programmatically Adjusting Timing and Triggering Configuring Channel Properties Page Page Acquiring, Analyzing, and Presenting Completing the Application Developing an Application Using LabVIEW Page Using a NI-DAQmx Channel Property Node in LabVIEW Specifying Channel Strings in NI-DAQmx Text Based ADEs LabWindows/CVI Measurement Studio (Visual Basic 6, .NET, and C#) Programmable NI-DAQmx Properties Calibration External Calibration A Specifications Amplifier Characteristics Filter Characteristics System Noise Stability Digital Input/Output Physical Maximum Working Voltage Environmental Safety Electromagnetic Compatibility CE Compliance Waste Electrical and Electronic Equipment (WEEE) B Removing the SCXI-1141/1142/1143 Module Removing the SCXI-1141/1142/1143 Module from MAX Removing the SCXI-1141/1142/1143 Module from an SCXI Chassis Page C Common Questions Page Page Page Glossary Symbols Page Page Page R S Page Index A B C D E F G H I L M N O P R S T V W