National Instruments SCXI-1321 Manual de usuario descargar pdf

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January 2003

321924C-01

SCXI -1321 OFFSET-NULL AND

SHUNT-CALIBRATION HIGH-VOLTAGE

TERMINAL BLOCK INSTALLATION GUIDE

This guide describes how to install and use the SCXI-1321 offset-null

and

shunt-calibration terminal block with the SCXI-1121 module. You can

only use the SCXI-1321 terminal block with SCXI-1121 revision

C or later

modules. In addition to the 18 screw terminals, the SCXI-1321 has circuitry

for offset-null adjustment of Wheatstone bridges, and a socketed shunt

resistor for strain-gauge shunt calibration. This terminal block was

primarily designed for Wheatstone bridge transducers such as strain

gauges, although it can easily accommodate thermocouples, RTDs,

thermistors, millivolt sources, volt sources, and current-loop receivers.

Thermocouples have cold-junction compensation (CJC) support.

Conventions

The following conventions are used in this guide:

» The » symbol leads you through nested menu items and dialog box options

to a final action. The sequence File»Page Setup»Options directs you to

pull down the File menu, select the Page

Setup item, and select Options

from the last dialog box.

This icon denotes a note, which alerts you to important information.

This icon denotes a caution, which advises you of precautions to take to

avoid injury, data loss, or a system crash. When this symbol is marked on

the product, refer to the Read Me First: Safety and Radio-Frequency

Interference document, shipped with the product, for precautions to take.

bold Bold text denotes items that you must select or click in the software, such

as menu items and dialog box options. Bold text also denotes parameter

names.

™

ni.com

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Indice de contenidos

Pagina 1 - SCXI -1321 OFFSET-NULL AND

Pagina 2 - What You Need to Get Started

SCXI-1321 Terminal Block Installation Guide 10 ni.comAssuming a strain-gauge range with a gauge factor of GF = 2 and a quarter-bridge configuration, t

Pagina 3 - Connecting the Signals

Pagina 4

SCXI-1321 Terminal Block Installation Guide 12 ni.comFigure 5. Full-Bridge Nulling CircuitShunt CalibrationShunt calibration provides a method of adj

Pagina 5 - Installing the Terminal Block

Pagina 6 - Specifications

SCXI-1321 Terminal Block Installation Guide 14 ni.comgauge with a gauge factor of GF = 2, Vexc = 3.3 V, and R = 120 Ω produces the following:Vchange =

Pagina 7 - CE Compliance

Pagina 8 - Offset Nulling

321924C-01 Jan03*321924C-01*W3 Nulling circuit of Channel 2 is enabled (factory default setting)Nulling circuit of Channel 2 is disabledW4 Nulling cir

Pagina 9

SCXI-1321 Terminal Block Installation Guide 2 ni.comitalic Italic text denotes variables, emphasis, a cross reference, or an introduction to a key con

Pagina 10

Pagina 11

SCXI-1321 Terminal Block Installation Guide 4 ni.comFigure 1. SCXI-1321 Parts Locator Diagram1 Strain-Relief Bar2 Strain-Relief Screws3 Safety-Ground

Pagina 12 - Shunt Calibration

Pagina 13

SCXI-1321 Terminal Block Installation Guide 6 ni.comNote To minimize the temperature gradient inside the terminal block, move the SCXI chassis away f

Pagina 14 - Cold-Junction Compensation

Pagina 15 - RTD and Thermistor Excitation

SCXI-1321 Terminal Block Installation Guide 8 ni.comNote Refer to the Declaration of Conformity (DoC) for this product for any additional regulatory

Pagina 16 - *321924C-01*