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NI-DAQmx: Continuously Acquire Thermocouple Samples - Hardware Timed in LabVIEW

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Filename: cont_acq_thermocouple_samp.vi
Requirements: View

I. Description:
This example demonstrates how to make continuous, hardware-timed temperature measurement using a thermocouple.

II. Instructions for Running:
1. Specify the Physical Channel where you have connected the thermocouple.
2. Enter the Minimum and Maximum temperature values in degrees C you expect to measure. A smaller range will allow a more accurate measurement.
3. Enter the scan rate at which you want to run the acquisition.
4. Specify the type of thermocouple you are using.
5. Thermocouple measurements require cold-junction compensation (CJC) to correctly scale them. Specify the source of your cold-junction compensation.
6. If your CJC source is "Internal", skip the rest of the steps.
7. If your CJC source is "Constant Value", specify the value (usually room temperature) in degrees C.
8. If your CJC source is "Channel", specify the CJC Channel name.
9. Specify the appropriate Auto Zero Mode. See your device's hardware manual to find out if your device supports this attribute.

III. Block Diagram Steps:
1. Create a Thermocouple (TC) temperature measurement channel.
2. Get all the channels in the task.
3. Convert channel(s) array to a comma-delimited channel string.
4. This attribute is set to compensate for input offset errors. May not be supported by all devices*.
5. Call the Timing VI to specify the hardware timing parameters. Use device's internal clock, continuous mode acquisition and the sample rate specified by the user.
6. Call the Start VI to program and start the acquisition.
7. Read N samples and plot it. By default, the Read VI reads all available samples, but you can specify how many samples to read at a time and the timeout value. Continue reading data until the stop button is pressed or an error occurs.
8. Call the Clear Task VI to clear the Task.
9. Use the popup dialog box to display an error if any.

* If your device does not support Auto Zero Mode bypass Step 2, 3, and 4.

IV. I/O Connections Overview:
Connect your thermocouple to the terminals corresponding to the Physical Channel I/O Control value.

Requirements


Filename: cont_acq_thermocouple_samp.vi

Software Requirements


Application Software: LabVIEW Professional Development System 7.1, LabVIEW Base Development System 7.1, LabVIEW Full Development System 7.1
Language(s): LabVIEW

Hardware Requirements


Hardware Group: Multifunction DAQ (MIO), SCXI
Hardware Model: PCI-6010, SCXI-1125, PCI-6014, PCI-6023E, PCI-6024E, PCI-6025E, PCI-6031E, PCI-6032E, PCI-6033E, PCI-6034E, PCI-6035E, PCI-6036E, PCI-6040E (PCI-MIO-16E-4), PCI-6052E, PCI-6053E, PCI-6071E, PCI-6110, PCI-6111, PCI-6115, PCI-6120, PCI-6122, PCI-6123, PCI-6132, PCI-6133, PCI-6143, PCI-6153, PCI-6154, PCI-6220, PCI-6221, PCI-6221 (37-Pin), PCI-6222, PCI-6224, PCI-6225, PCI-6229, PCI-6230, PCI-6233, PCI-6238, PCI-6250, PCI-6251, PCI-6254, PCI-6255, PCI-6259, PCI-6280, PCI-6281, PCI-6284, PCI-6289, SCXI-1102, PCI-6013
Driver: NI-DAQmx 8.0

 
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This example program (this "program") was developed by a National Instruments ("NI") Applications Engineer. Although technical support of this program may be made available by National Instruments, this program may not be completely tested and verified, and NI does not guarantee its quality in any way or that NI will continue to support this program with each new revision of related products and drivers. THIS EXAMPLE PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND AND SUBJECT TO CERTAIN RESTRICTIONS AS MORE SPECIFICALLY SET FORTH IN NI.COM'S TERMS OF USE (http://ni.com/legal/termsofuse/unitedstates/us/).