Express vi thermocouple reading temperature increase as temp decrease

Hi there,
I'm using a labiew express vi to take a measurement from a j-type thermocouple. I have, however noticed that a (real) temperature increase is shown as a temperature decrease indicating that I've wired the thermocouple in the opposite way to what labview expects. Is there any way to fix this other than by stripping down my system and redoing my cable?
Cheers,
Aaron

I don't think so.
The CJC math takes into concideration the glavonic potential between the different metals.
So just flip the wires and this will serve as big warining for you some time in the future.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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NI PXI 4351 read temperature

Hi,
I'm trying to read temperature from TBX-68T connected to NI PXI-4351.
I see PXI-4351 in my hardware explorer, it show me right data in test panel.
But, I can't found any tools for reading temperature in LabView!
I installed drivers for NI PXI 4351
http://joule.ni.com/nidu/cds/view/p/id/285/lang/en
but still noresults. Driver didn't contain any examples for reading.
I use LabView 10 and I have NI DAQ Traditional 7.4.4
so, I confused. How read temperature?

JaredRo wrote:
Hi kmcdevitt,
The SC Express product family was specifically designed to take advantage of the PXIe architecture and therefore the timing circuitry on the PXIe-4353 is not designed to be compatible with the PXI platform. There are no plans to design any of the SC Express products in the PXI form factor.
Jared,
Please explain what it is that makes the PXIe-4353 so special that there can not be a PXI-4353.
This 32-Channel, 24-Bit, Thermocouple Input Module does 90 S/s/ch sample rate in high-speed mode or 1 S/s/ch sample rate in high-resolution mode. Surely you are not claming the the PXI platform's architecture and timing circuitry can not hadle the troughput generated by the 32 channels of 24bit data at 90Hz.
Jared, it is not a pleasent fealing to be prommised that the new signal conditioning cards are going to be made for your soon to be purchased PXI-1045 chassises, and later find out from an Applications Engineer Jared that it has been in the plans to never make PXI versions of signal conditioning cards. How would you feel if you purchased about 30 PXI-1045 18 slot chassises with PXI Embedded RT controllers with the promiss that if you bought the controllers and chassises that NI would continue to develope new Signal Conditioning and Other PXI Cards for your chassises. Just buy them, and the new PXI cards will come. How would you feel when you were told to be patient and just wait till next years NI week. How patient would you be after the second year of being told to be patient until the next year's NI week? How patient would you be after the third year of being told to be patient until the next year's NI week? I have been recently asked to be patient again. NI Week 2012, there may be something. And now you tell me that there will never be anything.
I just don't buy it that there is something about the PXIe architecture and therefore the timing circuitry that is required for 90 Hz data.
Kevin.

How do I take a thermocouple reading with a pci6025E?

How do I take a thermocouple reading with a pci6025E? I have seen some postings with scxi-1112 modules which I do not have. I need advice from the ground up. Do I need external circuitry, can I just wire both leads of the thermocouple to Ain0 differential pins, what vis are necessary in the actual programming... If there is an example program or anything else that might seem relavent? I appreciate any help.

This is most probably a result of multiple factor that make the measurement imperfect:
- You're not using signal conditioning, so your resolution is definitely very reduced. Any temperature drift in the board could cause a big difference in the reading. I recommend you run your vi for approximately half an hour, unplug the accessory and perform a self calibration. This will have the board at the operational temperature you're expecting and will give you the best results.
-I personally would recommend using a different sensor type (RTD or Thermistor) as the CJC source, in order to obtain an accurate measurement, otherwise you have a bit of a "chicken and egg" problem, because you're using thermocouple 2 as the CJC for thermocouple 1, but what are you using as the CJC source of thermocouple 2?
- Are both your thermocouples of the same type and manufacturer? Due to the nature of the thermocouple itself, you can find slight variations between thermocouples from different vendors, due to the purity of the metals used. While this would usually be almost impossible to detect, it might be driving your voltage just enough to be in the next detectable voltage step (again, due to the reduced resolution).
- I've worked with temperature sensors for a while, and I'd still recommend that you try some sort of signal conditioning in order to increase your accuracy. Even a small amplifier and a passive lowpass filter will do great. I know you said you don't have SCXI, but if you want some lower cost ready to use applications you might consider looking at the SCC Carriers and modules we have.
I hope these suggestions help. Please let me know if you have any other questions.
Daniel

Tracing OSA data automatically when thermocouple reading stabilized

Hello,
        I am working on a temperature application. I have two parallely working VIs. One is for tracing data from an Optical Spectrum analyzer and the other is for monitoring thermocouple reading. I combined these two and made a VI that records the Optical Spectrum Analyzer data when the thermocouple reading stabilized.
        The problem is the code requires user feedback. I mean the VI ask the user whether to trace the data or not. I want the process to be automated completely so that I can leave the set up overnight. I want computer to record the OSA data everytime to a different column of .csv file. And since the wavelength column will always be the same, the computer can only record the power data.
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Attachments:
code.zip ‏146 KB

   By saying user input, I mean specifying the location of file. In the code 3650.VI, when temperature condition is met, a dialog appears and asks me whether or not to trace the data in a trace.csv file and asks for a file location. I want a stationary file and write all the OSA data,only power column, to be written into that file.Every time to a different column,of course.
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trace.JPG ‏248 KB
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Thermocouple reading

Hi,
I am working with a type K thermocouple and I use a LM 35 temperature sensor to get an accurate CJC. I have got an external serial device were I do the voltage measurement of both (K and LM35), that means I get the voltage value as string using VISA in Labview.
I would like to use the thermocouple reading vi for the linearization. My questions are:
Which option should I choose on the CJC sensor input of the thermocouple reading vi?
Can I connect the value that I get from the lm 35 to the CJC voltage input of the thermocouple vi?
Thanks

Hi Navarro,
thank you for your answer.
The first thing you have to define, is the Temperature Unit you want to get as the output of the Converter VI. Please refer to the LabVIEW help for the options:
Convert Thermocouple Reading VI - LabVIEW 2014 Help - National Instruments
http://zone.ni.com/reference/en-XX/help/371361L-01/lvinstio/conv_thermcoup_read/
As you described, your serial device returns scalar singular values to you, choose the scalar option of the converter VI.
The CJC options depend on your reference sensor. You can use a voltage or current reference, depending on what signal comes from the reference. Please refer to the help and the following link for more information:
What is CJC and Why Does My Data Acquisition Board or Signal Conditioning Unit Include a CJC Sensor? - National Instruments
http://digital.ni.com/public.nsf/allkb/E332E1D829059FB5862570AE005066B3
I hope, this helps.
Best regards,
Melanie

Thermocouple reading stop updating

Hi,
I am having a problem with a cRIO application and a NI 9213 module. I have a heater application and I am using the NI 9213 to read the temperature values of the heaters.
When I am using the heater to heat the system, the
NI 9213 suddenly (after reading for a few minutes)stops updating the
temperature values and is stuck to the old value. The time and
temperature at which it gets stuck is different every time. I have some other analog and digital modules in my system and they continue updating without problem
I verify my loop an it never stop, but by any reason the thermocouple reading stop updating the values. I am running in scan interface. Any help to solve this issue will be greatly appreciated. I am working in a new application with a short dead time.
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Hi Sebastian,
To get the 9213 working again I have to reboot the controller or make any change in the module properties like change from "hi rtesolution" to "hight speed" or something like that.
Attached is my code. It just a vi to test my inputs and outputs.
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I have a DAQ signal accessory connected to a laptop via a 6024E DAQ card. I am attempting to connect a type K thermocouple to the thermocouple port on the signal accessory and take temperature readings. The VI that I have set up is a slightly modified 'continuous thermocouple reading' example VI. I am having problems getting accurate readings. The temperature fluctuates 30-40 degrees between readings. This is impossible do to the lack of thermal variations in the environment. Please help!

Nah. I think we've isolated the problems.
It sounds like noisy inputs to the DAQ board.
As I said, TCs are very prone to noise on the line, and normally there's a filter on the TC to eliminate the noise, and just get the DC component of the TC--but you don't have that.
Therefore, to get the same effect, you're going to have to average many readings, which will in effect average out the AC component.
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Hi All
This is the configuration of my apparatus
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PCI-MIO-16E-4 card
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I have a Temperature sensor driver error as follows:
2011 Mar 17 19:53:28 GB2FCC202EA %MODULE-4-MOD_WARNING: Module 12 (serial: JAF1435BFPG) reported warning due to Temperature sensor driver error in device 49 (device error 0xc310020b)
2011 Mar 18 03:09:15 GB2FCC202EA %PLATFORM-4-MOD_TEMPFAIL: Module-12 temperature sensor 1 failed
exception information --- exception instance 2 ----
Module Slot Number: 12
Device Id         : 49
Device Name       : Temperature-sensor
Device Errorcode : 0xc310020b
Device ID         : 49 (0x31)
Device Instance   : 00 (0x00)
Dev Type (HW/SW) : 02 (0x02)
ErrNum (devInfo) : 11 (0x0b)
System Errorcode : 0x00000046 Temperature sensor driver error
Error Type        : Warning
PhyPortLayer      : Fibre Channel
Port(s) Affected : none
Error Description : sensor_read_temp: failure reading temperature from sensor 0
DSAP              : 0 (0x0)
UUID              : 0 (0x0)
Time              : Thu Mar 17 19:53:28 2011
                    (Ticks: 4D8258A8 jiffies)
Temperature:
Module   Sensor        MajorThresh   MinorThres   CurTemp     Status
                       (Celsius)     (Celsius)    (Celsius)
12       Outlet1         n/a             n/a         n/a        Failure
It looks a match for CSCsw41181 - however we don't see the following condition against any interface:
'Error disabled - SFP vendor not supported'
We tried reseating an SFP on this module but still no SFP vendor not supported condition.
Any other known bugs or do we have to treat it as a hardware issue?
thanks

Hi,
If it is related to CSCsw41181, a reload of the module would clear the condition.
If you can schedule a maintenance window to reload the module, that may be the least
intrusive next step (keep in mind that reloading the module will be disruptive to all the ports
on that module).
Regards,
Ken

Thermocouple reading (w/ Built-in CJC Source) only works on random SCB channels

I am using LabVIEW 8.2.1, a PCI-6255 card, and an SCB-68 terminal block. I have a Type K thermocouple with a thermocouple calibrator which I am trying to measure. Here is the problem, first, using the attached VI, I have tried to read this TC using AI0. Everytime I use AI0 I get the error saying Built-In CJC is not available. When I use any other channel, this error disappears. The second problem, when I use a channel other than AI0, I am only able to successfully read the TC on random channels. For example, it only works on AI13 to AI15. For the channels that it does NOT work on, I am able to see the correct voltage through MAX, however the AI Read TC VI does not for some reason give an accurate reading.
Does anyone know why I would not be able to use AI0, and why I am only to use certain channels for this TC? This makes absolutley no sense and I have tried swapping the SCB, the DAC Card, and the cables. I have reinstalled drivers and LabVIEW also.
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Thanks
Solved!
Go to Solution.
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test.vi ‏28 KB

bkb wrote:
So AI0 is the CJC value? And I have to specify CJC Channel when I read the TC? Why is it that I got this to work when specifying Built-In source, and wired the thermocouple to AI15? And why does it not work on other channels?
Not sure if this helps you but...
Thermocouple reading are often differential measurements since they are typically very small values. To get differential readings two AI channels are paired up so half of the channels go away when you set things up for differential measurements. So could you double check the documentation for your device to ensure you are wiring the thermocoules properly? Correct pair, proper polarity, and proper TC type specified.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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Need some help to understand how to work with this. In trying to use the express VI to setup DAQ to measure temperature I have found that half of the channels setup differential and half single ended.
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Express vi thermocouple reading temperature increase as temp decrease

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