SCXI 16-Channel RTD Module

Overview

The National Instruments SCXI-1503 RTD module provides 16 differential

input channels, 16 channels of 100

cold-junction (CJ) sensor channel. The NI SCXI-1503 is ideally suited

for measuring resistive transducers, such as RTDs or thermistors. Each

channel has an amplifier with a selectable gain of 1 or 100 and a lowpass

filter with a 5 Hz cutoff frequency to reject 50/60 Hz noise. The SCXI-1503

can programmatically connect each input to ground, which greatly

improves its accuracy by enabling a self-calibration of each input to

reduce offset drift errors. You can multiplex several SCXI-1503 modules

and other SCXI modules into a single channel on the data acquisition

device, greatly increasing the number of analog input signals that you

can digitize. The SCXI-1306 is a front mounting terminal block that offers

screw-terminal connectivity for the SCXI-1503.

Analog Input

Each of the 16 differential analog input channels feeds to a separate

instrumentation amplifier with a programmable gain of 1 or 100. Each

channel has a fixed 100

through a fixed two-pole, 5 Hz lowpass filter. The CJ sensor input

channel reads the sensor temperature from the terminal block. The

temperature sensor is for cold-junction compensation of thermocouple

measurements. The CJ sensor channel also passes through a 5 Hz

lowpass filter to reject unwanted noise on the SCXI-1503. Along with

the other 16 input channels, the CJ sensor is multiplexed to the output

buffer, where the data acquisition device can read it.

Current Source Operation

SCXI-1503 current sources continuously provide 16 channels of 100

μA

current excitation. These current sources are on whenever the SCXI

chassis is powered on. SCXI-1503 current sources are designed to be

accurate within ±0.05 percent of the specified value with a temperature

drift of no more than ±5 ppm/°C. The accuracy and stability of these

current sources make them especially well-suited to measuring

resistance to a high degree of accuracy.

Calibration

The SCXI-1503 is shipped with a calibration certificate and is calibrated

at the factory to the specifications described in

NI SCXI-1503

EEPROM, provide software correction values that your application

development software uses to correct the measurements for both offset

and gain errors in the module.

Measurement Services Software

NI-DAQmx measurement services software is included with all

National Instruments data acquisition and signal conditioning products.

This easy-to-use software tightly integrates the full functionality of your

NI data acquisition hardware with NI LabVIEW, LabWindows/CVI, and

Measurement Studio for Visual Basic software. High-performance

features include multidevice synchronization, networked measurements,

and DMA data management. Bundled with NI-DAQmx, the Measurement

& Automation Explorer (MAX) utility simplifies the configuration of your

measurement hardware with device test panels, interactive

• 16 channels of voltage or

resistive inputs

• Ideally suited for 2-, 3-, and 4-wire

RTD and thermistor measurements

• Programmable gain settings per channel

• 5 Hz filter per channel

• 100

μA current excitation

• 333 kS/s maximum sampling rate

• NI-DAQmx driver software

simplifies configuration, scaling,

and measurements

Operating Systems

• Windows XP/2000/NT

Recommended Software

• LabVIEW

• Measurement Studio

Other Compatible Software

• Visual Basic, C, C++

Measurement Services

Software (included)

• NI-DAQmx driver software

• Measurement & Automation Explorer

configuration utility

Calibration Certificate Included

NI SCXI-1503

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