Great variation on thermocouple readings

Similar Questions

• Thermocouple readings of the CRIO

  Hello

  I am fairly new to work with Compact RIO and I have problems with thermocouples that I have connected. My Setup has two modules of thermocouple in the NI 9213, NI 9211.

  I have connected a Type K thermocouple (one of each) both of the units. I used the vi FPGA target for reading from the Thermocouple channels as well as the CJC values and put two modules. I also CRIO vi which reference the FPGA vi, and then uses the values and feeds them to the "voltage convert to Temperature.vi. I've attached screenshots of the vi.

  The problem is the output I get is - 2 or 1 degree. When I touch the thermocouple increses value to about 5 or 8 degrees.  The room temperature is about 24 degrees.

  Can someone please help with where I'm wrong.

  concerning

  Bastien.

  Yes, it's the bad VI to be used with CompactRIO.  I'm not 100% sure why this does not work, but I don't know that the scaling VI that you use is designed to be used with NOR-DAQ, not CompactRIO.  Please open the examples for your modules to see the correct way to the scale of the CompactRIO thermocouple data.  I hope that these scaling methods will work for you.  You should find the examples here:

  C:\Program NIUninstaller Instruments\LabVIEW 8.6\examples\CompactRIO\Module Specific\

  This is the best advice I can give you, unfortunately.  If you need more detailed help, maybe someone on the forum knows more what to do about the scale of the data of thermocouples cRIO in degrees celsius.

• Variation of thermocouples (+ - 2 ° C) and are under the same conditions

  Hi, my English is not the best but I trust in your intuition and intelligence capacity.

  Actually Im connecting many thermocouples (type J) in a DAQ 9213. I managed to take all measures (7 thermocouples) and also the thermocouples are calibrated. My problem is that the 3 thermocuples give me one 20 ° c (60F) and the other 4 give me 22 ° c = 71.6 ° F, and all the thermocouples are under the same environmental conditions.  The easy solution is to put an offset and compensate for the error but it is not a good solution.

  Can someone tell me what is happening? I think it's wiring problem maybe the COM, but I've referenced the negative signal (low signal) to the COM, also tried not to referencing the negative signals to the commune, but the result is worse because the signals are going crazy.

  Please help me, please!

  Hi Jesus Hernandez

  Also remember that the thermocouples have a positive and a negative side, so if you plug wrong temperature will be different and it will decrease rather than increase when something warmer so close.

  Best regards

  Julio Mena

• NOR-4351 incorrect Thermocouple readings

  Had had problems of expierencing with our boards of NOR-4351, we have several and the only work is done without knowing why.

  I took a Board of Directors and setting up a new system with a new installation of windows XP SP3. I then installed TDAQ744.

  He installed, then XP recognized the device and install its drivers.

  Then, I set the properties of the 4351 for a TBX68T accessory.

  Then, I created a virtual channel to measure a thermocouple type j to channel 11, which is RM correctly.

  I put the refrence to user at 25deg C.

  I then had 23.899 ° c and it woudlnt change such as the thermocuple has been heated or cooled.

  I tried changin the ref built in, and then the reading went to 2800 or almost.

  I repeated with a different 4351, same problem.

  I changed the TBX68T with a CB68T

  My guess is a problem with TDAQ744, I can wipe the system and startover and install 7.2

  Very disappointed that we have made to buy these cards a few years ago that in-kind for them drop that left us in this impasse.

  Finally had the chance to install another system. Even found a replacement cable, or it turns out the problem. It was damaged enough to cause problems intermittly.

• Noise on the readings of thermocouple on the NI PCI-6225

  Hi all

  I have a problem with what appears to be static electricity caused by noise on thermocouples.

  We test with a sand as a medium flowing through a plexiglas window and measure the temperature in the stream. The interaction of mixture air/sand flowing through the plexiglas creates a significant amount of static electricity and our thermocouple readings are severely affected. Is there a way to filter the signal so that my data and off-scale obvious signal analysis tools ignore?

  The filtering I see seems to apply only to high frequency noise. I would like to cut the signals from the TCS to ignore all of the above measures 700DegF and under 32Degf.

  Thank you

  Hi Emi_emii,

  It might be useful to see what the current state of your VI acquisition is - just to get an idea of your overall architecture. I see a couple of alternatives.

  1. You could do some external signal filtering to get rid of the extra load on your son of thermocouple - see this valuable whitepaper on the topic of wiring: http://www.ni.com/white-paper/3344/en/
  2. The extent of the filtering software, you could use the cooker and force the function (http://zone.ni.com/reference/en-XX/help/371361J-01/glang/in_range_and_coerce/) on your data and the use of the Boolean output to hide your actual data or simply to force your MAX/MIN values

  Hope this helps!

• Registration of multiple Thermocouples

  Hello world

  I'm watching 4 Thermocouples simultaneously using a cDAQ-9174 and the NI 9211 thermocouple module. I am very new to LabView. I found a VI which seems to do what I want on the forum (I'll hang), but I can't seem to operate beyond recognition the first data channel.

  I think I missed something simple when it comes to select the analog inputs of the VI fort, in order to get the four channels to work.

  I am also open to suggestions for a better example VI that can connect 4 thermocouple readings at the same time.

  Thanks for your help!

  You have to hit the ": 3" at the end of the round.  Select channel 0 from the list, and then add the ": 3" to it.  Who says DAQmx you want channels 0 to 3.  I have a slightly different material (a 9213 instead of 9211) but your VI read the 4 first thermocouples I connected and stacked the traces in the first four graphs.

• Thermocouple configured in module module-9221

  Hi all!

  Nice day!

  I try to configure thermocouples type K 6 through the NOR-9221 analog input module and chassis cDAQ-9174. I'll be able to get the direct temperature readings outside this module not being a thermocouple module? Otherwise? Please suggest me how to get the temperature for this add-on module-9221 directly! Quick help will be very appreciated!

  Best regards!

  Tajim

  To build on what the broken arrow, the 9221 is really not at all optimal for measurement by thermocouple.  Most of the measures by thermocouple are between 0 to 80 mV.  The module 9221 is a 12-bit with a range of ±60V module.  The width of the code for this module is about 15 mV and your accuracy is 156 mV.  All your thermocouple readings will be lost in the noise for this add-on.  I would recommend the 9211 or the 9213 for measurement by thermocouple, because each has CYC and is specially designed for thermocouples.  If you want to try an external amplifier, which can run, but you will probably need something that can amplify from 0 to 80 mV to 0 - 60V.

  Kind regards

• control thermocouples

  Hey, I have a strange problem and I hope someone can help. I have been using a program for about 6 months now that basically keeps a cold temperature next to a heat sink and maintains a warm temperature on the other side.  Then I 25 hung in the meantime thermocouples to measure temperatures I can do the analysis of the material in the environment.  My problem is that all of a sudden the readings of the thermocouples were out of control and unpredictable.  I add me automation program so it could run several tests at the same time and in the process developed by this problem.  The weird part is that the problem is also past in the old version of the program now too, and that has worked perfectly for the last 6 months.  I have 25 hung thermocouples and temperatures will all look all right, but then 3-5 of them will be quite wrong at random.  What is interesting about this problem, it is that when I change the thermocouple which become the use of heaters to maintain the set temperature, the values that were wrong again on the right and some other thermocouples start giving invalid data.  The installation program uses a NI 9213 and 3 NI 9211 inputs for thermocouples.  It also uses one OR 9401 to control heaters through a box pulse width modulation power we have.  Someone at - he never experience something like this or have any ideas?  Thanks for any help

  Hey Nathan,.

  Thanks for the ideas.  I ended up spending to playback of multiple samples as you suggested and this error has not popped up once again, so hopefully that fixed this issue.  I think I solved the problem of both weird thermocouple readings! I think that I had a ground loop problem which I fixed it by the grounding all thermocouples to a metal table.  For all those who on their getting odd unexplained readings, certainly experiment with ground everything correctly.

• invoke the node (screw in a parallel work library)

  Hi all

  I'm evaluating a temperature probe. For this I must watch the thermocouple readings. Thermocouple is attached to the FP-TC-120 of temperature module. Moreover, I have to acquire data from the optical spectrum analyzer. I use 3650.VI to monitor the temperature and 86140 B Capture of Trace_Screen .llb (2) o trace data of OSA.
  I try to use Invoke node VI for Spectrum Analyzer trace data. For this, I specified the path to the necessary file as an input for the code. The problem is that the necessary VI (write Trace to File.VI) is within a Bachelor of law. folder and need codes to operate completely.
  It is when I run the code (and when the condition of stability is met) the computer asks me to save data of Spectrum Analyzer in a file called trace.csv. When I press ok, it simply registers an empty file with a header (Power (dbm) wavelength (nm)). Apparently it works in parallel with the other VI. How can I make use of the VIs within a .llb file with call node VI or should I use another VI to combine temperature monitor VI VI of tracing data.

  The second problem is with the temperature stability criterion. In the attached VI, I check if the thermocouple reading is within the range of stability of 0.8 degree 900 seconds. I want to change that. I have
  you want to check the stability of the temperature by comparing the final data with the previous ones. Y at - there no specific VI which should be used to check fluctuations of waveforms?

  Thank you very much

  Deniz says:

  Now, I struggle with timing. The problem is that if I put a timer inside a case structure, it disables the time VI

  This is not what is actually happening. What is happening is that the loop must wait until the delay function is completed before you can continue to the next iteration. There are several ways to solve this problem. Here are 2:

  • Instead of having a time delay within the structure of the case, use a shift register to keep track of the last time a trace has been captured. If the time is greater than or equal to 1 minute and you are supposed to be captured, and then do the capture and reset the timer. Thus, the structure of the case would be headed by 2 conditions rather than 1. It is a relatively simple change.
  • Place trace capture in a separate and independent loop. The case structure would be as is inside this independent loop. You must use a property node or a local as a flag variable, so that the trace capture can be triggered. For example, you must create an indicator of the output of the or less? function so that you can read the value in the other loop.

  I recommend method 1.

  PS, I just noticed that the "Trace Xfer" VI has already incorporated in writing in a spreadsheet file .  As it is, you will get a dialog box asking you for a file name. You can either:

  • Delete the entry in the worksheet in the "Trace Xfer" VI file as you do in your top-level code.
  • Delete the entry in the worksheet of your first level VI file and add a path control to the "Trace Xfer" VI and past in the path to the file you want to write.

• Cold welding of 2 ° C error

  I use a PCI-6229 to measure temperatures using thermocouples type K and a channel of thermistor for cold junction compensation.  The thermistor cricuit, I've done seems to work very well.  It is the reading of good ambient temperature, which is be 20.7 ° C and is essentially the same as what I get on three different thermocouple panel meters, more it agrees with my cacluations of this thermistor voltage-temperature relationship.  This thermistor is settled in a terminal used on the CB-68LPR, right there where plug thermocouple extension cables.  It fits perfectly in one of the small holes.

  But when I use this channel of thermistor for CCM my measures by thermocouple readings are constantly low, about 2 ° C, even using thermocouples of same that I use with the Panel counters.  The error of-2 ° C is constant in all of my channels of thermocouple.

  With junctions to measure thermocouples is the same temperature as the CB-68LPR, the tensions of thermocouple to the places where the thermocouple extension cables are connected to this block should be 0 volt.  I've confirmed with a voltmeter. If the PCI-6229 map should see 0 Volts on the channels for thermocouple, either by NIST, 0 ° C tables.  It seems that all this has to do is now to add measurements of temperature thermistor.  Better, I can understand, this addition is not right, or not, 0 Volt is equal to 0 ° C, on this forum or something else happens.

  I use DAQmxCreateAIThrmstrChanIex to configure the channel of the thermistor and DAQmxCreateAIThrmcplChan to configure the channels of thermocouple.  The CJC sourse is DAQmx_Val_Chan.

  No idea what's going on, what I am doing wrong, etc.. ?

  Thank you.

  Looks like you do everything right, but THST is close enough to the accuracy of the system.  The K type thermocouples only have an accuracy of 1.5 degrees.  Furthermore, a K type thermocouple voltage changes by about 40 microvolt/degree, and the accuracy of the 6229 (when it is in its smaller range of +/-2V type 0) is 112 microvolts.  It is generally recommended that you do some conditioning on thermocouple inputs before reading signals data acquisition card.  It SCC and SCXI modules already have the conditioning of signals, and the CJCS included.  It can allow you to get better results, but you are still limited by the precision of the thermocouple.

  -Christina

• Is there a single SCXI module adapted to the entries for mixed probes?

  I'm trying to set up an SCXI system to receive signals from a number of different types of sensors. I have a large number of thermocouples for which I decided to use the SCXI-1102 module. I also have a unique pressure sensor (unknown spec so I'll assume type of strain gauge), a unique accelerometer (once again, unknown technique) and possibly a few tensions ahead right (unknown County and spec so assume - 10 v to + 10 v Beach max).

  Is there a single SCXI module through which I can acquire voltage signals, accelerometer and pressure sensor? Or maybe just use 2 modules instead of 3 if I have a SCXI-1530 for my accelerometer and an another module for the tensions and the pressure transducer? I was watching the module SCXI-1121, which looks promising for the tensions and pressures but then was unsure as to what block of connection to use for the combination of signals (possibly, I could live with a - 5V to + 5 v range if necessary).

  (Additional info: I use TC-2095 blocks with my SCXI-1102 module, can not really use spare entered on those voltage inflows).

  Thanks for any help.

  CASE NO.

  It's expensive,

  Thanks for your inquiry. You obviously already did a lot of research on this issue. I fear that it is unlikely that you will be able to use a single SCXI module to perform any function you listed. Necessary accelerometers such air conditioning specialist, it will take a module - as you mentioned already, something like the 1530 (4 channel accelerometer input module) would be ideal.

  However, you have a number of different options for the pressure, voltage and temperature measurements.

  For example, you could buy a mudule 1520 for your measurements of pressure and then use a generalist 1102 b for voltage and temperature (need you the connection block insulated from 1303 to condition the thermocouple readings... and work around the CYC technology for pressure readings).

  Or, you may use the module thermocouple 1102 for your temperature readings and then use a 1102 b to take pressure readings and the pressure. Of course, that would require making your own bridge to the pressure sensor configuration, but this should be pretty easy.

  Before making any final decision, I would recommend that you call your local branch of the NC and speak with a sales representative. Perhaps, a member of the sales field staff might actually come see discuss you it face to face.

  Finally, it looks like you have a number of ways relatively high for some of your reading, is why you decided to use the SCXI platform. I was just wondering if you had considered compact DAQ (cDAQ), which combines the DAQ hardware with signal conditioning. Top spec, ease of use, lower number of channels. Swings and roundabouts I guess.

  I hope this has been of some use to you.

  Best wishes

• HP 5940 - color cartridge status light flashes with new HP 97 cartridge

  Just installed a new HP 97 cartridge and the light flashing color cartridge status. Put in old 95 HP cartridge and the lights are out, but this cartridge is empty. I have cleaned all connectors (inside the printer and the cartridge), tried reinstalling several times. Any ideas or am I stuck with a bad cartridge? The only difference I see between the cartridges, it is that the 97 is a greater variation of the 95. Thanks for any help.

  Never forget, faulty cartridge. He took over and replaced it, it works now.

• Connection of door AND dynamic data

  The program compares a thermocouple readings to a constant. The superiors are introduced into a door AND exits. However, if one of the inputs can be connected in dynamic data at the port of entry of the door AND. When the same data of the other DAQ is sent, it gives an error. Interchanging the ports also gives the same error.

  Can I use a Boolean Dynamics to the converter so to counteract this? The output of the gate AND then entered the port of exit DAQ.

  Thank you.

  Hello

  try something like the logic shown in the attached photo.

  Let us know if that's what you're looking for.

• Alarm connect once

  Hello world

  I have an interesting question with the connection of an alarm "disconnected thermocouple" as part of a condition to the monitoring application.

  I connect thermocouple readings to 5 Hz when a thermocouple becomes disconnected increases reading in 1372, which is detected and should sound the alarm.  The application generates a string at that time (and publishes on a table) by telling the user what thermocouple has disconnected and any action taken (for example, turning off the radiator).

  I would usually include a snippet of code, although the code uses the property nodes (as the code of error log is in another loop) making it virtually unreadable.

  My problem is that the alarm is published in each iteration.  I need to keep control of other failures of thermocouple, but disable one that has already occurred.  I thought to defining a variable 'already written' in a registry to offset for each case of error, but it became quickly messy.

  Help (or ideas of a better way to do it!) are appreciated.

  Pete

  Pete.Dunc wrote:

  Are there any suggestions for a more effective architecture to have the same result?

  Well, some of your code is not necessary. For example, you don't need to choose between the file name and "-" in the lower loop, because it's already done in the upper loop.

  • It seems preferable to maintain the fixed-size table and rotate the lines if necessary.
  • I would recommend 10 entries in the table, otherwise you miss some if all are disconnected at the start of the program.
  • I remove all the constants of diagram 'false' in domestic affairs and take the tunnel exit to "use by default if the thread continues".
  • I think that you still get not a newspaper because you accidentally a REAL inside of the case 'High '. Check this!

• Error-50103 took place at DAQmx start Task.vi

  Hi all

  I'm having quite the difficulties of merging the two screws I'm trying to get the thermocouple readings and pressure readings in a VI. I think the two AOs are competing for the resources of the clock. Please forgive my noob-ness. I am very new to LabVIEW and it is not the most intuitive. I have attached the thermocouple VI I try to insert in the VI pressure. I appreciate all help. Two screws were working before the merger.

  Sorry!

  You gave the wrong link, here's the good: http://digital.ni.com/public.nsf/allkb/3296BA2AEF586B7386256D6D00528E3D?OpenDocument