Ni 9211 thermocouple will only read 1414.4

[Steeltiki]

Hello,

I have a cDAQ 9172 with one 9211 thermocouple module reading only one continuous measurement off Aio 1. I read the manual and calibrated the module and I keep getting a reading of 1414.4 off the thermocouple. I'm using a type J thermocouple. The range the module needs to read is 25 C to 300 C. What is the proper setup for the DAQ to read that thermocouple? I've done the calibration several times but I'm still get the same result. Can someone please walk me through the setup like I’m an idiot cause I don’t know where I’m going wrong. Also I change out the thermocouple and checked it with several others and the reading is the same. This thermocouple is acting as a fail safe to shaker system and must read continuously.  

Thank you to anyone who can provide me with information. 

[Joseph_Loo]

Have you configured the module in MAX for the thermocouple? Have you used Max to read the temperature?

[Steeltiki]

I checked the calibration for the MAX and it is 23 degree C which is acceptable. However when I setup a task and run the test panel I get a value of 1.4136k when the specified units are degrees C. This is also the same reading I get when I run the actual program. How do I get it to read degrees C? The range need for the thermocouple to read is 25 to 300 degrees C. The settings for samples to read is 1 at a rate of 50Hz continuous.

[Ever_Song]

Hi Steeltiki,

First off, a question:

1) What type of thermocouple are you using (i.e. J, K, T, etc.)?

Things to try:

1) Run a task that only measures the voltage into the device and see if the voltage reading makes sense.

2) If you have LabVIEW, try using one of the shipping examples for thermocouples. These can be found by opening up LabVIEW and select Help > Find Examples. In the NI Example Finder, browse to Hardware Input and Output > DAQmx > Analog Measurments > Temperature.

If these suggestions do not work, it would be helpful if we could have more information about your setup. Could you please link a Measurement & Automations Explorer (MAX) report? This can be done by opening up MAX and selecting File > Create Report. In the wizard, select custom report and check Data Neighborhoods, Devices and Interfaces, and Scales.

[Joseph_Loo]

If you read the spec on the USB device, I believe it is limited to about 14 samples per second on an aggregrated mode. If you sample too fast, there is a possibility that you will not get the accuracy. Result is you may be able to differentiate temperatures in 10 of degrees only. Look at your design.

When you run MAX, have you run it continuously and try to warm the thermocouple to see if it is working by watching the temperature increasing, e.g., hold the thermocouple in you fingers. Make sure you are not looking at the cold junction temperature.

Explain how you are attaching to the thermocouple channel in your VI. Your explanations and what you are saying is starting to diverge. I am not familiar with all the devices but I don't believe MAX provides calibration of the device.

You never mention what thermocouple is being set in your device and if you set the thermocouple type in MAX.

[Steeltiki]

Hey Bill and Joseph,

Thank you for both replying.

So the type of thermocouple that I’m using is a type J. I check the thermocouple that I’m using and it does produce a normal reading using a different cdaq and a different module.

I used DAQ assistant for voltage, the conditions are, signal input range 80m to -80m, units volts, terminal config differential, acquisition mode differential, acquisition mode N samples, samples to read 3, rate 3. This produced a flat reading of 80m.

 Did a search in Labview for examples of thermocouples and ended up using "cont. acq thermocouple sample-int clk-open thermocouple detection. vi" chose the correct cdaq and channel. This produced an code 200452 "specified property is not supported by the device or is not applicable to task."

 I have 2 of these 9211 modules so I tried the other one and got the same results.

I shortened the thermocouple wire length, changed the aio port and it produced the same results.

Then I selected a port that did not have thermocouple (empty port) and ran both the daq assistant for voltage and the thermocouple and the results showed the value of 80m for voltage and 1414.4k amplitude for thermocouple.

It looks like I’m not getting any signal from either one of the 9211 modules. How do I fix this?

[Joseph_Loo]

We are trying to be methodical about your problem. Your terminology does not match up and your explanation does not make complete sense.

1.  What is the configuration of the themocouple stated in Max? We are not interested what you are saying but what Max is saying. Screen shot of the configuration would be nice.

2.  Did you run the test panel? What kind of values are being outputted. Did you raise the temperature on MAX and see the rise in temperature or not? Screen shot will be nice.

The above 2 will tell us if your device is configured properly.

3.  How are you connecting to the unit? Are you using a task or creating the task?

4.  Do you have a simple example showing your problem, e.g., just reading the thermocouple. A posted VI will be nice to look at.