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Acquire Temperature Data From a Thermocouple

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This example shows how to read data from NI devices that support thermocouple measurements.

Discover Devices That Support Thermocouples

To discover a device that supports thermocouple measurements, access the device in the table returned by the daqlist command. This example uses an NI 9213 device. This is a 16 channel thermocouple module and is module 6 in the chassis.

d = daqlist("ni")

d =

  12×4 table

     DeviceID                 Description                    Model             DeviceInfo     
    ___________    __________________________________    _____________    ____________________

    "cDAQ1Mod1"    "National Instruments NI 9205"        "NI 9205"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod2"    "National Instruments NI 9263"        "NI 9263"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod3"    "National Instruments NI 9234"        "NI 9234"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod4"    "National Instruments NI 9201"        "NI 9201"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod5"    "National Instruments NI 9402"        "NI 9402"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod6"    "National Instruments NI 9213"        "NI 9213"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod7"    "National Instruments NI 9219"        "NI 9219"        [1×1 daq.DeviceInfo]
    "cDAQ1Mod8"    "National Instruments NI 9265"        "NI 9265"        [1×1 daq.DeviceInfo]
    "Dev1"         "National Instruments PCIe-6363"      "PCIe-6363"      [1×1 daq.DeviceInfo]
    "Dev2"         "National Instruments NI ELVIS II"    "NI ELVIS II"    [1×1 daq.DeviceInfo]
    "Dev3"         "National Instruments PCIe-6363"      "PCIe-6363"      [1×1 daq.DeviceInfo]
    "Dev4"         "National Instruments PCIe-6363"      "PCIe-6363"      [1×1 daq.DeviceInfo]


deviceInfo = d{6, "DeviceInfo"}

deviceInfo = 

ni: National Instruments NI 9213 (Device ID: 'cDAQ1Mod6')
   Analog input supports:
      -0.078 to +0.078 Volts range
      Rates from 0.1 to 1351.4 scans/sec
      16 channels ('ai0' - 'ai15')
      'Voltage','Thermocouple' measurement types
   
This module is in slot 6 of the 'cDAQ-9178' chassis with the name 'cDAQ1'.

Add a Thermocouple Channel

Create a DataAcquisition, change its scan Rate to four scans per second, and add an analog input channel with Thermocouple measurement type.

dq = daq("ni");
dq.Rate = 4;
ch = addinput(dq, "cDAQ1Mod6", "ai0", "Thermocouple");

Configure Channel Properties

Set the thermocouple type to K and units to Kelvin (the thermocouple type should match the sensor configuration).

ch.ThermocoupleType = 'K';
ch.Units = 'Kelvin';
ch

ch = 

    Index    Type      Device       Channel    Measurement Type            Range                 Name      
    _____    ____    ___________    _______    ________________    _____________________    _______________

      1      "ai"    "cDAQ1Mod6"     "ai0"     "Voltage (Diff)"    "+73 to +1523 Kelvin"    "cDAQ1Mod6_ai0"

Acquire and Plot Data

Use the read command to acquire data.

data = read(dq, seconds(1));
plot(data.Time, data.cDAQ1Mod6_ai0);
ylabel('Temperature (K)');