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Choosing a Thermocouple Measurement Device

Publish Date: Jun 01, 2016 | 43 Ratings | 3.49 out of 5 | Print

Overview

This document introduces the available measurement platforms for thermocouple temperature sensors.

Table of Contents

  1. Platforms for Measuring Thermocouples
  2. NI Compatible Thermocouples
  3. Next Steps

1. Platforms for Measuring Thermocouples

Compact Measurements

Benchtop or Field Measurements

A CompactDAQ system consists of a chassis, NI C Series I/O modules, and software. Chassis can connect to a host computer over USB, Ethernet, or 802.11 WiFi or operate stand-alone with a built-in controller. With over 50 measurement-specific modules and 1-, 4-, and 8-slot chassis, CompactDAQ provides a flexible, expandable platform to meet the needs of any electrical or sensor measurement system.

  • Multiple timing engines for multiple acquisition rates
  • Advanced counter functionality from NI-STC3 technology

Embedded Data-Logging Measurements

CompactDAQ controllers offer a high-performance platform for embedded measurements and data logging. Controllers feature an integrated computer and nonvolatile storage, so that CompactDAQ can be deployed without an external computer.

  • Includes Intel multicore processing, up to 32 GB nonvolatile storage, and 2 GB RAM
  • Simultaneously stream continuous measurements with sample rates up to 1 MS/s per channel

Extreme Ruggedness and Advanced Control

CompactRIO is a reconfigurable embedded control and acquisition system. The CompactRIO hardware architecture includes a reconfigurable FPGA chassis and an embedded controller. You can use CompactRIO in a variety of embedded control and monitoring applications.

  • A variety of reconfigurable chassis featuring an FPGA for custom timing, analysis, and control
  • Open embedded architecture with small size and extreme ruggedness
What Is CompactDAQ? What Is CompactDAQ? What Is CompactRIO?

C Series I/O Modules With Integrated Signal Conditioning for Temperature With Thermocouples

NI 9214 

For C Series I/O modules specifically designed for the measurement of thermocouples, NI offers the NI 9211, NI 9212, NI 9213, and the NI 9214. These modules contain all of the signal conditioning required to measure thermocouples simultaneously. They also feature 24-bit ADCs for up to 0.02 °C measurement sensitivity. The NI 9213 and NI 9214 have a higher channel count, up to 16 channels, and 250 Vrms channel-to-earth ground safety isolation. The NI 9212 provides 8 isolated channels for improved safety and noise immunity. The NI 9214  provides an isothermal terminal block for measurement accuracy up to 0.45 °C, several CJC sensors, and an autozero channel for offset error compensation.

Thermocouple Data Logger—Up to 16 Channels

This thermocouple data logger consists of one 4-channel (NI 9211), 16-channel (NI 9213), or isolated 4-channel (NI 9219) C Series thermocouple module and one USB (NI 9171), 802.11a/b wireless (NI 9191), or Ethernet (NI 9181) single module carrier. Each module is specifically designed for thermocouple measurements and features integrated signal conditioning that provides direct connectivity to your sensors. The 24 bits of resolution along with built-in CJC offer superior accuracy. The isolated 4-channel module includes 250 Vrms channel-to-earth ground isolation for safety, noise immunity, and high-common-mode voltage range.

 

High-Performance and High-Channel-Count Systems

 

The PXI platform offers a variety of chassis, controller, and module options so you can create a measurement system to meet your specific application needs. The SC Express strain modules can provide up to 0.02 percent accuracy at up to 102.4 kS/s. PXI scales to thousands of strain and bridge-based measurement channels for large applications and provides both wired and wireless synchronization options.

  • Configurable desktop, rack-mount, and distributed multichassis systems
  • Compatibility with a wide range of sensors and transducers
  • More than 1,500 PXI modules available, including CAN, vision, motion, and GPS

PXI I/O Modules With Integrated Signal Conditioning for Measuring Thermocouples

The SC Express family features PXI Express DAQ modules with integrated signal conditioning for sensor measurements, such as thermocouples and other temperature transducers.

NI PXIe-4353 

32-Channel, 24-Bit, Thermocouple Input Module

The NI PXIe-4353 thermocouple input module provides integrated DAQ and signal conditioning for temperature measurements. This module includes increased accuracy and synchronization features for scalable measurement systems from low- to high-channel counts.

The NI PXIe-4353 features 32 channels with three 24-bit ADCs and operates with high-speed (90 S/s per channel) and high-resolution (1 S/s per channel) modes. It is designed to be highly accurate with 0.3 °C typical accuracy for the module and terminal block. The module has two autozero channels for offset compensation as well as open thermocouple detection to identify disconnected thermocouples.

The high accuracy is attributed to the TB-4353 isothermal terminal block that includes eight CJC channels. It has a unique design that optimizes thermal conductivity between the thermocouple terminals and the CJCs for an isothermal error as low as 0.25 °C. The TB-4353 is a front-mount terminal block with screw terminal connectivity.

 

NI InstantDAQ Technology

 

 

The USB-TC01 thermocouple measurement device features InstantDAQ technology so you can instantly take temperature measurements with your PC. Just plug it in and built-in software for viewing and logging data automatically loads. No driver installation is necessary. Connect to any USB port to use your PC as a display and monitor data in real time. The USB-TC01, which is compatible with J, K, R, S, T, N, and B thermocouples, uses a standard miniplug for easy thermocouple connection.

Additional applications for generating alarms, scheduled logging, logging to a spreadsheet file, and logging under threshold conditions are available as free downloads. For even further customization, you can build your own applications with LabVIEW graphical programming and NI-DAQmx driver software (requires version 9.1 or later).

 

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2. NI Compatible Thermocouples

 

 

For cost-sensitive applications, NI offers ready-made thermocouples and individual packets of thermocouple wire with the measuring junction provided at one end. These thermocouples are available in 1 m (39.4 in.) and 2 m (78.7 in.) lengths. For shorter lengths, trim the thermocouple to the desired length and then install it into your application. Ready-made thermocouples are ideal for starter or educational applications.

Features

  • Available in 1 m and 2 m lengths
  • Available in J, K, T, and E types
  • Ideal for starter and educational applications
  • Measures up to 900 °F (482 °C)
  • Measuring junction provided

 

 

NI field-cuttable thermocouples meet a wide variety of temperature application needs. With field-cuttable thermocouples, you can cut the probe to the desired length from 3.5 in. to 24 in. (8.9 cm to 61 cm). Therefore, you can use one stock of thermocouples for all your temperature measurements, which reduces inventory cost and production downtime. Available in grounded and ungrounded versions, these probes can measure up to 900 °F(482 °C). For applications using thermal wells, the optional spring-loaded fitting reduces installation time while ensuring contact with the thermal well. Each probe has glass braid insulated leads and is sold individually.

Features

  • Available in J, K, T, and E types
  • Cuttable from 24 in. to 3.5 in.
  • Measures up to 900 °F (482 °C)
  • Reduces inventory cost and downtime

 

 

Use extension wire to connect your thermocouple elements to your measurement and automation systems in less harsh environments. It is important to match your extension wire type to your thermocouple element type. Otherwise, errors can be introduced into your system.

Features

  • Available in 30 m and 300 m spools
  • Available in Jx, Kx, Tx, and Ex types

 

 

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