Erratic Temperature measurements with FP-TC-120

I have two FP-TC-120 modules on a furnace system. When the temperature
reaches a certain level (930°C) my readings become very erratic. I have
shielded all of the tc's and everything else that is connected to the
FP bank to eliminate EMI noise. The interesting thing is that when I
hook another temperature reader in Parallel with the Fieldpoint module,
my readings are normal on both the new reader and Fieldpoint. Without
the parallel reader, the readings will jump all over and abort my
crystal growth runs due to a false high temp alarm. The problem affects
one or more tc's at a time, and is not specific to only one of them.
One time Tc #2 may fail, then next time may be #4. There is no rhyme or
reason. I have been chasing this problem for three weeks to no avail.
Please advise what could be causing this. I have several FP-TC-120
modules on other furnaces that operate with no problems. This is the
first time I have had trouble.

I apologize for the delay. I haven't been working on this system today.
I'm not sure if it is an Omega unit or some other unit, but it is
powered by the computer's USB port. I also have the same effect with
the old mux board that the fieldpoint is replacing. If the Mux board is
attached in parallel with the Fieldpoint, the readings are fine. I
should note that the mux board is not even hooked up to anything other
than the TC's (meaning nothing at all, no power, no PC, just sitting
there with only TC's on it). The C or COM terminals on the Fieldpoint
are not hooked to the power supply common. The erratic readings are
intermittent, and when the power to the heaters is off, the problem
goes away. Meaning, if I heat the oven up manually to 1000°C, and turn
off the heaters, the TC's will read fine. It is only when I am trying
to control the heat that the problem arises. This definitley points to
noise, but as I said, I taken great measures to eliminate the noise. My
next step tomorrow is to ground every thing that can can be grounded
and even replace all TC's with shielded versions (currently I have a
home-made shield set-up with standard TC's). If these do not work, I
may have to look into purchasing, or developing a low pass filter to
eliminate the noise.
Thanks for your help. If you think of anything else, let me know. I
will post the solution when I find it so you know and others may
benefit.
-Mark

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Temperature measurement with LV...

Will this NI system work with my LV 8.0 Profesional edition?
NI USB-9211A
http://www.ni.com/temperature/high_accuracy.htm

oetcl,
please do not hijack threads for your own questions. Please post new questions in new threads.
Nevertheless a question from my side:
I understand it that you have connected the USB 9211a using an USB hub. Is the device recognized correctly if connected directly to the laptop?
hope this helps,
Norbert
Message Edited by Norbert B on 02-24-2009 09:09 AM
CEO: What exactly is stopping us from doing this?
Expert: Geometry
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Temperature measurement with Raytek MX4?

How can i make the communication of Raynger MX4 and add the Serial End Mode for Writes to the VISA Instr property node and use TermChar as a value.Can somebody send me a Example , [email protected]

hello wenliang,
basically you could set all VISA properties via a VISA propertynode (see the attached image).
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Help needed with temperature measurement

hi guys
I need some help with temperature measurement. I've got a NI PCI 5229 card and a powertransmitter. The power transmitter is programmed to output a 4-20mA (0°C - 100°C) signal. How can i get labview to convert this mA signal to displaying it as temperature? Please include a lot of detail as I am a first time labview user.
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Hi Jaco,
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TC measurements with PXI 4351 DAQ Card

(I am using version 6i of LabVIEW). I am trying to create a VI that will use a PXI 4351 Card with a TBX-68T to take 4 thermocouple continuous measurements. I am also acquiring 8 voltages with a 6030E and TBX-68 and writing them to a file. My voltage data acquisition is modeled after "Buffered Continuous Analog Input.vi" I would like to aquire voltages and temperatures in the same vi, but using different devices and accessories. (I need a higher frequency for the voltage acquisition, and more precision with the temperatures). Is there a subvi I can use to collect the temperature data in the same vi as my voltage? I don't want the thermocouple DAQ to interfere with the voltage DAQ, either.
I tried the NI435x thermocouple.vi
but I couldn't get the Built-in Cold Junction Sensor to work or figure out how to combine it with my exisiting voltage acquisition. I also got NaN for my readings, and I checked the wire connections in all the sub vi's as suggested by another solution.
Any comments would be great. Thanks in advance.

Claudia-
Thanks for the response.
Regarding the CJC- When I switch it on, the temperature readings I get are very random, roughly negative 1 degrees. (I am operating right now at room temperature, and will be using J-type TC's to measure ~43 degrees C). Also, when I use the built-in CJC, the aquisition rate seems to slow down considerably. When I use the "user specified" everything seems to be ok, including the aquisition rate.
I measured the resitance of the Thermistor on the TBX-68T and it was about 5000 Ohms, as expected.
Just to make sure: When using the TBX-68T, do I need to hard-wire a thermocouple to Channel 1/auto-zero and another to channel 0/CJC? Because I connected a TC to channel 0 right now, but I wasn't 100%
sure.
I've attached my main vi and two sub vi's that I am using for the voltage aquisition part of my project. (Note:the current measurements are just voltage measurements multiplied by the recipricol of the resistance it was measured across, ie. 10).
I would like to keep this file as is because it writes to a file exactly the way I want it to. I'd like to have the temperature aquisition with the 4351 in the same vi as the 6030E so that they both stop and start at the same time. I am just not sure how and where to log the temperature data since there will be fewer data points than the voltage data. Any suggestions? Should I write two separate files? can I somehow append them?
Thanks again. Hope to here from you soon.
Attachments:
EBlackMainDAQ.vi ‏107 KB
Save_Data8.vi ‏45 KB
Build_String_Array5.vi ‏33 KB

RTD Temperature Measurements using LabView 2013 and MyRio

Hey everyone. I am VERY new to LabView programming and working with a MyRio. I need to figure out how to measure the resistance of a 2 wire RTD to find a temperature utalizing the MyRio and LabView. I am pretty lost on how to do this. Does anyone know some good resources for making the LabView program off of the tops of their heads? I've figured out how to measure from specific pins, but I am not sure how to get it to constantly output a voltage from the output pins.
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Hi JoshEpstein87,
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http://www.ni.com/myrio/setup/getting-started/
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Applications Engineer
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Temperature measurements display incorrectly after opening a project.

Dear All,
I am having some difficulty in setting up LabView SignalExpress version 5.0.0 to display RTD temperature measurements from the NI9217 module and the NI cDAQ-9178.
I have two problems:
1. I cannot set the waveform chart to show the desired time interval; I need to set the time interval displayed on the chart to 30 minutes. This means that before taking 30 minutes of continuous measurement the user would see a fixed grid with fixed time boudaries and the plot moving from the left hand side of the screen to the right hand side of the screen. After thirty minutes of measurements have been taken, the chart would begin to "scroll" so that the earliest measurements move off the screen and the chart still displays the time interval of 30 minutes.
2. I need the chart to display correctly immediately after the project has been opened; When I open the project and click the 'run' button, the windows are all displayed correctly but the readings are not displayed correctly, the chart only displays one short line to the right of the screen and a very short time interval of less than a second. I can correct this by changing to a Time XY Graph and then back to a waveform chart but need this to display correctly as soon as the software is opened. The incorrect and the corrected chart are shown below:
The chart below is displayed when the software is opened and the run button is clicked. This chart style is incorrect because the temperature line is displayed in the bottom right of the chart and only for a short time interval.
The chart below is closer to the required graph described in point 1 but I cannot set the time interval to stay fixed at 30 minutes, nor can I make the software display the graph like this on opening, I always have to switch to a different chart type and then switch back to a Waveform chart to replace the format above with the format below:
Any help would be appreciated,
Thanks,
Matthew

Hi Matthew,
We should be able to used this function to save the graph settings as well. I have just tried it on my system and got it to work. the procedure I undertook was:
Open my Signal Express Project
Turn off x-axis auto scale (Right click on graph >> X Scale >>Auto scale)
Enter Properties (Right click on graph >> Properties)
Select the scales tab
Select 'Relative To' under the Timestamp Type.
Set the min as 0 and the max as 1800...Press OK
View >> Layouts >> Make Current Project Layout Default
Save
In this case I used the Relative Timestamp Type but you can use whatever time stamp you wish. When opening up this project after doing this the graph is formatted as required immediately.
Let me know how you get on with this.
Regards,
Aaron. E
Applications Engineer Team Lead
National Instruments
ni.com/support

NI WSN 3212 takes incorrect measurement with external power

Hi, all.
I have a problem with temperature measurement using NI WSN 3212 node with external power supply. The value randomly changes for all four channels. It happens if at least one thermocouple connected to any channel. If I disconnect all thermocouples, the values of channels are NaN. I have not this problem when node powers by battery.

Hi,
1. Check for the correct power cord that you have attached with the node to give the external power.
2. Check for any external power supplied to the channels from your side.
3. Reboot the node and try to obtain the temperature from thermometer.

Frequency response measurements with pxi-5922

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Claudia-
Thanks for the response.
Regarding the CJC- When I switch it on, the temperature readings I get are very random, roughly negative 1 degrees. (I am operating right now at room temperature, and will be using J-type TC's to measure ~43 degrees C). Also, when I use the built-in CJC, the aquisition rate seems to slow down considerably. When I use the "user specified" everything seems to be ok, including the aquisition rate.
I measured the resitance of the Thermistor on the TBX-68T and it was about 5000 Ohms, as expected.
Just to make sure: When using the TBX-68T, do I need to hard-wire a thermocouple to Channel 1/auto-zero and another to channel 0/CJC? Because I connected a TC to channel 0 right now, but I wasn't 100%
sure.
I've attached my main vi and two sub vi's that I am using for the voltage aquisition part of my project. (Note:the current measurements are just voltage measurements multiplied by the recipricol of the resistance it was measured across, ie. 10).
I would like to keep this file as is because it writes to a file exactly the way I want it to. I'd like to have the temperature aquisition with the 4351 in the same vi as the 6030E so that they both stop and start at the same time. I am just not sure how and where to log the temperature data since there will be fewer data points than the voltage data. Any suggestions? Should I write two separate files? can I somehow append them?
Thanks again. Hope to here from you soon.
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EBlackMainDAQ.vi ‏107 KB
Save_Data8.vi ‏45 KB
Build_String_Array5.vi ‏33 KB

SCXI-1328 temperature measurement accuracy

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Hello efour,
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http://www.ni.com/advisor/accuracy/
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General information about taking thermocouple measurements can be found at:
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http://zone.ni.com/devzone/conceptd.nsf/webmain/4C54819521D3503786256D73006E8BE9?opendocument
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TBX-68T temperature measurement errors

I am using a TBX-68T with a PXI 4351 card to measure the temperature of a steel plate while the plate is undergoing a TIG (electric arc) welding process. To my knowledge (and based on past experience), the device is connected properly in MAX, with the TBX-68T selected as the accessory. In MAX it also passes the tests. Using the built in CJC and specifying a K-type thermocouple at a range of +/-0.625v, MAX reports temperatures of -80C. The temperature remains nearly the same as the range is increased, but if I change the range to +/-3.75v, the temperature suddenly jumps to 100+C. I used the Measure Thermocouple (with accessory).vi that comes with the driver, and it gives me the same readings. Furthermore, when I initiate the TIG welder the card reads extremely negative (-10e9) temperatures.
What is odd, is that I have used these devices for the exact same process in the past and it generated believable results.
How can I fix the current temperature offset problem? Could I have possibly damaged the unit? Is it possible to use the TBX-68T to reliably detect temperature in arc welding process?
Thanks,
William

Hello,
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If you cannot read the proper voltage on the card, then it is possible that the card will need to be repaired. Please update us so we can help you further.
Thank you
Regards,
CharlesD
Digital MultimetersSchedule a Free 1 Hour LabVIEW Tutorial with an NI Applications Engineer

Measurement with NI 9211

Hello,
I want to use a PT 100 or 1000 with my existing NI 9211.
But for using this setting I need an external power supply.
I know normally you supply a PT 100 with 1mA and 1mW.
CAn someone help me with the electric circuit.
thanks
patrick

Hello pwotawa,
unfortunately I have to tell you that this module cannot be used with a PT100. It is meant to be used with thermocouples.
See this post as reference:
http://forums.ni.com/t5/LabVIEW/measure-temperature-pt100-with-cRIO9211/td-p/1919201
You can also find this information in the modules manual:
http://digital.ni.com/manuals.nsf/websearch/1A7D292F8762FBC68625775A004C99BA
For use with PTD, you will need something like this: NI9217
http://sine.ni.com/nips/cds/view/p/lang/de/nid/208804
If you have got one of these, please find the manual here, which tells you how to connect a RTD on page 10:
http://digital.ni.com/manuals.nsf/websearch/754EF1A59C48FB73862573D0006CC9AB
I hope I could help you.
Have a nice weekend,
Best regards!
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Intern Application Engineering | NI Certified LabVIEW Associate Developer (CLAD) | NI Germany

Which board is good to produce 5v TTL and temperature measurement?

I want to use Labview to control a valve controller,which contects 6 solenoid valves. This instrument accepts 0-5V TTL signals. I need to switch the valves on/off below 1 second. Which Ni board is good for this application as well as temperature measurement I want also?
Thanks a lot for your suggestion.

Sheng,
One of National Instruments E Series multifunction DAQ devices should provide all of the functionality you require. You may want to also consider using SCC signal conditioning for your temperature measurements. With regards to the digital output, you will want to verify that the current drive provided by an E Series device is great enough to control the valve. If it is not, the NI 6509 digital I/O device provides high current drive. Below, I have included links to the appropriate product pages:
E Series Multifunction DAQ
SCC Signal Conditioning
NI 6509 Product Page
Good luck with your application.
Spencer S.

Accurate differential temperature measurements

May I connect my RTD's in series to improve differential temperature measurement accuracy. I currently use an SCC RTD01 together with a DAQCARD. My differential temperatures are in the magnitude of 0.5 - 1.0C.

Tom,
After reading your second post, I realize that you want to couple the RTD's in series. Originally, I thought you wanted to couple the modules in series.
Ok, you can place the RTD's in series, but this will not increase your measurement accuracy. If you decide to experiment with this setup, make sure you provide sufficient current excitation for both RTD's. What will happen is the experimental error you receive at the first thermocouple will be seen by the next RTD in series, so your error will not decrease.
I advise you to try the oversampling idea to increase your accuracy. Here is information regarding this form of accu
racy improvement.
You can use this accuracy calculator to calculate the accuracy of a given SCXI module and compare this value to the measurement accuracy you're seeing with the SCC module.
I hope this helps! Please let me know if the averaging technique helps to increase your accuracy.
Best of Luck,
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Sound Power Measurement with 4472

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Is it simply because NI has not yet written a software for Sound Power Measurement using 4472 or is it technically NOT possibly to do Sound Power Measurment using 4472?
Gurdas Singh
PhD. Candidate | Civil Engineering | NCSU.edu

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2. It is important to note that any toolkit add-on to LabVIEW "could" be written by the end user using the very same subVIs distributed with the Full Development System. Sound power is merely a term used to describe a particular mathematical method involved in transforming the acquired sound data from the real domain to the frequency domain. The mathematical methods have been used for many decades. I use my own custom code originally developed in FORTRAN, converted to C++, and now embedded in a code interface node (CIN). The issue to resolve comes down to a) do you have the in-house capability to write and support detailed code development, or, b) do you purchase the toolkits and thereby achieve the capability very quickly. Although the toolkits are expensive, the burdened cost of, say, 1
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Erratic Temperature measurements with FP-TC-120

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