Recommended NI Hardware for Thermocouple Measurements

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Hardware: Multifunction DAQ (MIO)>>E Series, Multifunction DAQ (MIO)>>M Series, Multifunction DAQ (MIO)>>Portable>>USB-9211A, SCXI>>Modules>>SCXI-1102, SCXI>>Terminal Blocks>>SCXI-1303, SCXI>>Modules>>SCXI-1112, SCXI>>Modules>>SCXI-1125, SCXI>>Terminal Blocks>>SCXI-1328, SCC>>Modules>>SCC-TC01, SCC>>Modules>>SCC-TC02, SCC>>Modules>>SCC-TC03, Counter/Timers (TIO)>>Connectivity>>SCB-68, Multifunction DAQ (MIO)>>Connector Blocks>>SCB-100, FieldPoint>>Analog I/O Modules>>FP-TC-120, Modular Instruments>>High-Precision DAQ (Dataloggers)>>DAQCard-4350, Modular Instruments>>High-Precision DAQ (Dataloggers)>>PXI-4351, Modular Instruments>>High-Precision DAQ (Dataloggers)>>TBX-68T

Problem:
What is the best NI hardware to use for taking thermocouple measurements?

Solution:
There are various configurations of NI hardware available for thermocouple measurements depending on the application needs. Some of these factors might include accuracy, channel count, cost, or environment. Below are several configurations with comments. The hardware discussed are as follows: E Series, M Series, SCXI-1102, SCXI-1303, SCXI-1112, SCXI-1125, SCXI-1328, SCC-TC0x, SCB-68, SCB-100, FP/cFP, FP/cFP-TC-120, NI 435x, TBX-68T, USB-9211A

E or M Series DAQ board with SCXI-1102 and SCXI-1303 terminal block

Best choice for high channel count applications. Up to 3072 channels per DAQ board. (32 channels per module)
SCXI-1303 has isothermally constructed terminals to minimize cold junction temperature gradients.
Has built-in configurable open thermocouple detection. Detectable in software.
One CJC sensor per terminal block.
Slower sample rates. Max rate = 100 kHz / (number of CJCs + number of channels).

E or M Series DAQ board with SCXI-1112

One CJC sensor per channel.
Most accurate for high channel counts. Up to 768 channels per DAQ board. (8 channels per module)
Has built-in open indicator LED's on front of module. Automatically configured.
Slower sample rates than the SCXI-1102. Since there is one CJC sensor per channel, the Max rate = 100 kHz / (2 * number of channels)

E or M Series DAQ board with SCXI-1125 and SCXI-1328 terminal block

SCXI-1125 isolation allows thermocouple measurements with high common-mode voltage.
SCXI-1328 has isothermally constructed terminals to minimize cold junction temperature gradients.
Less accurate than SCXI-1102 or SCXI-1112
One CJC per terminal block. 8 channels per module.

E or M Series DAQ board with SCC-TC0x

Low channel count
CJC per channel for better accuracy
Good if inputs other than thermocouples are needed which will also require signal conditioning

E or M Series DAQ board with SCB-68 or SCB-100 terminal block

Low cost
Low channel count
Allows other general purpose inputs if needed.
Fast sampling rates for a thermocouple.
One CJC sensor for all channels. CJC is sampled once per channel scan.

FieldPoint or Compact FieldPoint NI FP/cFP-TC-120

Good for distributed thermocouple measurements.
Software-timed updates.
16-bit resolution.

NI 435x with TBX-68T terminal block

Most accurate NI configuration for thermocouples. Accuracy -- 0.42 °C for J-type thermocouples
24-bit resolution.
Very slow scan rates. 60 readings/s.
Low channel count. 14 channels.

USB-9211A

Low channel count. 4 channels.
24-bit resolution
Plug-and-play compatible via USB
Small and portable device

Report Date: 06/20/2003
Last Updated: 03/09/2006
Document ID: 2YJEQIBG

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