NEITHER 9237 quarter bridge absolute accuracy

Similar Questions

• Understand and improve the absolute accuracy

  Many sculptures absolute accuracy calculated the computation of absolute precision in the manuals of the user for the use of modules in series C the following entries:

  • TempChangeFromLastExternalCal = 70 * C
  
  
  • TempChangeFromLastInternalCal = 1 * C
  
  
  • Sigma/Std-dev = 3
  
  
  • # of samples = 100

  I have a few questions about these two values listed above TempChange

  1. Why such a low value of only 1 has the TempChangeFromLastInternalCal * C; modules are continually doing internal calibration automatically?
  
  
  2. Regarding TempChangeFromLastExternalCal, I read correctly that NEITHER is the calculation of accuracy, assuming that the material has seen a +/-70 * C delta temperature since the last time it was calibrated externally. that is calibrated to 25 * C, but runs at 95 * C?

  To improve the absolute accuracy, I'm curious to know if the following two statements would improve accuracy:

  1. The material exists in an environment temperature controlled with a + / delta 10 * C ambient temperature. Can I use the value of 10 for TempChangeFromLastExternalCal if it has been calibrated at room temperature outside?
  
  
  2. If I'm short so HAVE them + HAVE terminals and a channel not used by COM and the extent to which results can be subratcted of readings of all other channels, I essentially elimited the error of the formula of absolute precision shifting?

  For completeness, for absolute accuracy formulas are:

  Absolute accuracy = ± (VoltageReading * GainError + VoltageRange * OffsetError + NoiseUncertainity)
  GainError = ResidualAIGainError + GainTempco * TempChangeFromLastInternalCal + ReferenceTempco * TempChangeFromLastExternalCal
  OffsetError = ResidualAIOffsetError + OffsetTempco * TempChangeFromLastInternalCal + INL_Error
  NoiseUncertainity = (RandomNoise * sigma) /(# of samples)

  Hey Sean,

  Change in temperature refers to the temperature difference from the last time that you did these two calibrations and the current temperature unit. So if you did an internal and external calibration at 25 ° C, then you will find the difference between the current temperature and 25 ° C. This is valid for two years for external calibration (according to the data sheet) to answer your questions:

  (1) If you both internal as external calibrated at 25 ° c, and then assign TempChange 1 ° C if the environment is in a summer of 24 or 26 ° C.

  (2) if the room was 10 ° C when the measurement has been taken, both internal and external TempChanges is 15 ° C (because your calibration conducted at 25 ° C).

  (3) If you were doing an internal calibration at 10 ° C, then your internal TempChange would be 0 ° C and your external would be 15 ° C.

  Regarding tips, I do not have too. The best I can suggest is to use a lower range and a device that has a lower production, but I don't think that it would be viable for your application. The best try of course is calibrated as close as possible to the more uniform temperature.

  I found a VI that calculates the absolute accuracy of a device. Must be a lot of values, but it allows you to play with the values to see what you can afford. My calculations show you in your range, but be absolutely sure of these fluctuations.

  https://decibel.NI.com/content/docs/doc-9912

  Attached a photo of the values that I used to get this error. I'm sure that the devices are calibrated at 23 ° C. Here's the manual where I found the numbers that I used.

  http://www.NI.com/PDF/manuals/374231c.PDF

  Sorry for the confusion earlier, I hope that this post clears up a lot of information and if it's not please let me know.

  -KP

• NEITHER 9237 to RVDT R30A

  Dear all,

  I am a new user of systems OR and I really appreciate and need your help.

  I want to connect OR 9237 to RVDT R30A ASSY (the input voltage is 3VRMS). However, I have a load cell connected to my OR who needs 10 v excitation and I need (or have?) to use 10v for all entries. I talked to a guy in MEASSPEC (the company we bought our rvdt of them), and he said, we can use 10v excitement if our signal conditioner can support 30mA. I searched the data sheet, but I could not understand what are the components! Can you clarify for me? NEITHER 9237 can support this control?

  I appreciate your help if you introduce me some books or web pages that can help me improve my understanding of the modules and the knowledge of electricity.

  Best regards

  Bardiya

  PS: I'm not sure that I used the right forum for this question or not. I really appreciate your help.

  My first question is why you use RVDT?  They have a few advantages, but it can be difficult to use without specialized equipment.  In case you need a refresher on the RVDT technology, take a look at this.  Ideally, if you must use an RVDT for your application, you will use a special signal conditioning and measure RVDT a device like the NI SCXI-1540.  These devices, unlike the generic of the analog inputs and output devices proposed below, have specialized circuits to deal with the nuances of the RVDT technology.  You can learn more about these things here.

  RVDT need an AC source excitation and have an AC output including amplitude and phase varies linearly with the angular displacement.  So if you insist on using it in cRIO, since there is no series C LVDT/RVDT/resolver signal conditioning module, you will need two separate modules to use this device with cRIO.  One excitation of the AC and the other to measure the voltage AC power.

  Module of excitement: the data sheet for this specific RVDT tells ideally to a 3 Vrms, 10 kHz excitation source.  Since Vrms for a sine wave is approximately equal to 2.8 * Vpp wave, which means that you need a range of output of about 8.5 v p - p  Here are a few cards that could fit this specification: NI 9263, NI 9269, NI 9264 NI 9260.

  Measuring module: you can use any module analog input here that has enough channels and can taste a minimum of 20 kech. / s (with a frequency of 10 kHz of excitement, you'll exit will also be 10 kHz.)  Meet the criteria of Nyquist sampling to 2 * 10 kHz = 20 kHz sampling frequency).  You can find all the analog input C Series modules at least 4 channels of entry here.

  In short: use a specific measure RVDT if possible.  If this is not possible, explore other displacement measurement technologies that may be easier to use, as an optical encoder.  If none of these things are an option, you should be able to use the listed above analog input and output modules to interact with the cRIO RVDT, although it will take significant software development on your part.

• NEITHER 9237 external excitement - VeriStand 2013 SP1

  The voltage recommended for my pressure is + 10 VDC sensors. I prefer to use external excitation according to the NI 9237 manual, total power to the module is limited to 150 mW, which in my case is "four bridges complete 350 ohm at 3.3 V. (I'll use pressure transducers (4) 350 ohm full bridge). I use scanning for EtherCat engine and the NI 9237 in a chassis 9144 OR connected to a cRIO-9081. For troubleshooting, I have two transducers on a pressure calibrator and another RJ50 connection a NI 9949 escape. If I select "External excitement" and have my power supply of 10 V connected to the bass + EX, EX-connecteur, I get an invalid value for my pressure sensor. It is after the scaling of the calibration value. The gross value is also incorrect. If I let the value "External excitement" but shoot the EX +, EX-connecteur, the EX +, EX-tension (pins 6 & 7) will go to 4.735 V and I'll get a CORRECT pressure reading. If I select an internal 3.3V excitement, I'll get a statement of the correct pressure, but I am a little concerned about the resolution that recommended excitement is + 10 VDC for the pressure transducers. My question is: Why can't I use the external excitement? I have another application with a chassis PXI and EtherCAT and it works OK. I also tried to place a NI 9237 module in the chassis cRIO-9081 and get the same invalid value that I describe above.

  You have the latest version of the scanning engine and EtherCAT custom device? On the community page for this custom device, the last listed specifically done bug fix reference to this module. There is also a specific forum for this custom device which may be a good idea to post on as well if you have not already posted here about this problem.

• load cell 9237 + full-bridge: load cell_null_off_shuntcal.vi - error 200077

  I try to use load_cell_null_off_shuntcal.vi with load cell (Honeywell model 31, not amplified). I'm using LabView 8.6, cDAQ-9172 and NI9237. Entries: excitation10V internal; mV/V 2.1492 (calib. bin); weight 10 lbs max. resistance bridge 350 ohms (Honeywell specifications); 9237 internal shunt resistance 100 kohm; map of shunt R4 (default setting). Selected "offset null" and "shunt cal.

  Error-200077 occurred to Shunt calibration perform DAQmx
  . VI:1 (bridge) or the possible reasons:

  Measurements: Requested value is not a supported value for
  This property.

  Property: I. Bridge.ShuntCal.GainAdjust

  You asked:-61.980405e3

  Valid values begin with: 500.0e - 3

  Valid values ending with: 1.500000

  If "shunt cal' green button not selected, no error. Setting the gain should be about 1. Subvi DAQmx PerformShuntCalibration (bridge) .vi contains "Call library function node" which is locked (?).

  Any ideas?

  What is the location of item correct shunt for a full-bridge load cell? Change this location does not eliminate the error.

  Hello, YTC,.

  The problem is most likely in your external connections of the NI 9237 and the load cell.  As mentioned in NI 9237 Operating Instructions and specifications, page 9, SC + SC - pins must be connected to the terminals of the resistance specified in the .vi of Shunt calibration perform DAQmx (bridge) (in the case of a full bridge, it would be R3).

  Let me know if you still have problems with your calibration.

• NEITHER 9237 and SignalExpress

  I have a cDAQ-9174 with modules OR 9237 with SignalExpress 2011 for strain gage measurement. After a few problems and doing some research on this forum, I discovered that the minimum sampling frequency for the NI 9237 is 1613 samples/second. However, I need a sample of about 1-5 samples/second rate as my tests will be the order of 4 to 5 hours and record 1613 samples every second will make my too big data file. On the forum, I found these workaround solutions:

  Subset and resampling (http://zone.ni.com/reference/en-XX/help/371268M-01/expresswb/subset_and_resample/) seems to be the most recommended, however I have a few questions about this. I selected a range of subset of 0s to 1s and then choose a resampling of 200 Ms. that seems to be the more manageable sampling frequency, but then I have a problem with the export of the data collected. I get a message that says I can't export to Excel, as the data are 'not continuous' and can only convert to text. However, the text file is not really useful as it breaks down the data in individual games and puts the time in terms of dt. For small sets of data, it seems that it would be possible to manually determine every moment given by point, but I will receive a large number of data sets. I have tried uncheck the "optimize to run once" but still not the same type of data file. What makes a kind of aggrivating, it's in SignalExpress data view tab can display a graph of deformation over time, that I need in Excel.

  Another recommendation is to use the 'Statistics' using the collected samples, then changing the number of samples to change the rate. However, I prefer not to use this method because it seems to imply "at x time, average of the latter strain is y" rather than 'x time, strain is there' and I want just the value of the strain at every 0.5 s, 1 s, 1.5 s and so on (although I guess that how that differ from the subset and resample method?).

  The last recommendation I found suggested to use an N-sample acquisition, set to read two samples and then set a delay of acquisition of post about 1000 m that would have been a nice solution, but it seems that SignalExpress impossible to compile all the samples to read a log file, that I have seen only two data points when I opened it in Excel.

  I'd appreciate any help, thank you.

  Hello MAF101,.

  I ran your own project and it worked for me. I just used the following values:

  

  It worked very well, I managed to turn on logging. Then, I tried logging information in a txt file using the instructions below:

  

  I got the attached file below using a relative timestamp. It connected two samples per second.

  Concerning

  Frank R.

• NEITHER 9237, map of the c series

  
  

  Yes, the change of measure may mainly be due to the precision.

  I think that load cell specifications contain details of precision. It is usually in % of the maximum nominal weight.

  Trust that helps

• NEITHER 9237 Raccordementdu external excitation

  Hello

  I work with labview 8.6 and using a NI9237 mounted on a chassis.

  I use 4 guauges of strain with a voltage of 10V for which I need to connect an external excitation source.

  I can't find a way to do this? There are 2 boxes of samll with some connection terminals, but I don't know if I'm doing things.

  Also, do I need to change my connections in any way when I use an external excitation source?

  Karthik85:

  It is not black magic. The constant reading you get is actually the value of mv/V. Which must be multiplied by the corresponding voltage for the mV reading. Read this article and if all goes well he will clarify all black magic.

  http://digital.NI.com/public.nsf/allkb/21CA039D8F43C5188625729F005AC2F7

  Best,

  Santiago

• calibration OR 9237-200077

  I'm trying to calibrate the NI 9237 + NOR 9945 quarter bridge extensometer or max.

  I get the error-200077 occurs calibration of strain meters.

  Possible reasons:

  Requested value is not supported for property value,

  Property HAVE. Min

  Asked the value - 1.0E - 3

  Valid values begin wih 18.8988984e - 6

  Valid values ending with 103.843984e - 3

  Channel name: strain

  I've tried everything, the meter of different strain, different 9945 9237 different, different cables, different computers. everything.

  I changed all the settings I found in or max.

  I searched the forums and inernet and what is there is not help.

  Any ideas?  Please?  I'm so desperate.

  I just got the same error message again and again.

  What went down: when I set my limit min between the highest and lowest allowable values specified in the error and then dialog window have been, I had the same mistake all over again, but the highest values and more allowed bass displayed in the window had changed to completely different numbers.  This happened several times.  No matter what I put my limits, allowed values min max always change, so it would be mistake every time regardless of what I entered.  Sometimes he complain on the gain of shunt calibration factor, he couldn't put it is '+ inf' or '-inf '.  Looking closely at the calibration window, I noticed that NEITHER MAX read the same value of strain, with or without, the resistance of the shunt connected.  When the calibraion subtracted Y2 - Y1, he got zero, and the opposite of zero is started.  This is when I knew for sure it was something my son and began the search in there deeper.

  Cause: short in the wires running to the extensometer.  When the specimen has been assembled and bolted on the luminaire, the wires were hidden so that nobody could see them, and they were crushed between two metal components.

  Solution: look for shorts or other problems in the wiring itself extensometer. I imagine that if the strain gage circuit is open, you would see probably the same error of MAX NOR in this case as well.

  Recommendation: I ask OR to add more useful information in the dialog box for error, to offer the user to check the wiring, etc.

• Wavy jagged singal of 9237 at no load condition

  Dear forum users and employees of OR,.

  I would be grateful to you if you can solve my problem. My specimen is a simple piece of plastic 1 0.25 inch rectangular cross section with a length of 8 inches. I'm trying to measure the deformation (with the help of use general TML, Japan 1 mm gage length extensometer) in the sample by hanging dead in the sample weights. I am able to strain using the cDAQ 9178 chassis, NI 9237 module with accessory NI 9944 quarter bridge. For a given weight (so the applied load becomes a static), signal (output voltage) must remain constant independent of time. In addition, I also expect that when no load is present on the sample, the acquisition system data above should show constant, but the deformation of almost zero output over time. What is my problem only after offset removal and shunt calibrated correctly with the help of the wizard of LABView DAQ, the above data acquisition system shows a strain of output wavy stair of significant variation between maximum and minimum, even when the sample is at no load condition (the sample is simply placed on the table). In addition, even after loading the sample with a certain amount of dead weight, rather than get a constant signal, I always get a strain of output wavy stair (with more scale position zero load) over time. Please help me get a constant output signal for the data acquisition system above with and without load on the sample.

  Thanking you

  KSRKM

  
  

• How to connect 2-wire extensometer to NI 9237 of watchkeeping

  
  

  You can find the manual for the NI 9237 here module

  It's a good idea to buy a NI 9944 or accessory OR 9945 quarter bridge if you plan to use this module with quarter bridge configuration, but you can look at the diagrams below to see what kind of internal connections are implemented: connection of the gauges of stress and resistance Shunt to the NI 9237

  PS ad in the DAQ or forums instead of conditioning of signals Labview maybe get you better/more answers fast.

  See you soon

• Absolute precision PXI-6123

  Please see page 4 of the specifications for the device. The signal that I'm trying to measure through a shunt 30A: 300mV, but in most cases, the maximum value is about 10 A/100mV. The readings that we receive are not clean and are quite loud, when the hope is that they are quite clean.

  It seems that the smaller card voltage range is +/-1.25 V. According to the manual, the absolute uncertainty according to the table is 740 uV (or 0.74 mV). I watched it and it was quite high. I mean in 2A (20 mV) absolute uncertainty of 0.75mV is 3.75% and it is quite high. I realize that we use only about 4% of the voltage range and it is a problem, but I still think it could be better that it's - am I interpreting this right?

  If I interpret it correctly, then is card on par with the industry standards?

  Hello

  Please clarify, I was more in the way of solving problems to try and get the best representation of your signal! Take a look at this article by NOR retailer the absolute accuracy. You can calculate this using the values in the table on page 4 of the manual you mentioned.

  How to calculate absolute precision or the accuracy of the system?

  http://digital.NI.com/public.nsf/allkb/8BA2242D4BCC41B286256D1D00815B90

  There are three ways to calculate absolute precision in anticipation of your system design, although I'll add the specification on page 4 of the manual I believe is the number planned and tested by NOR. I apologize because I'm a little busy right now or I would run the numbers myself.

  Absolute accuracy specification is a signal that properly uses the +-1.25V range. A 0.74mV absolute precision in the schema of a 2.5Vpp signal is less than two-tenths of a percent error (0.185%). There are modules (as you mentioned) for smaller ranges of entry, that's why you have seen a performance much better with the-range 0.5 to 0.5. You might consider to amplify the signal in the range of +-1.25 to get the best performance with the PXI-6123. Although the distortion seems to be important in your application, using only 4% of the available range is just a case do not use the material best suited to your application.

  Kind regards

  Train of Finch

• Error-50150 when calling DAQmx perform compensated bridge removal Calibration.vi

  I have a question very similar to This One, but the opposite is happening. I create a task that contains 2 channels of analog input (strain gage quarter-bridge). One of the channels is on a cDAQ NI 9235 Module, the other is a cDAQ NI 9219 module. Both modules are in the same chassis OR cDAQ-9172. When I try to run the DAQmx perform compensated bridge removal Calibration.vi on the job, I get error-50150.

  If my task contains channels of only one of the modules cDAQ calibration completed successfully. Any ideas? I can't understand what is the cause.

  More information...

  LabVIEW 8.6.1

  DAQmx 9.0.2

  Toby

  Certified LabVIEW Architect

  Hi TobyD,

  This seems to be a variation on the other problem you have linked, CAR #4HDABJ0O in the legacy CAR Pb, alias #198928 in the BD of CAR new CAR.

  DAQmx has a special code for offset NI 9219 removal, to manage the NI 9219 special scale of watchkeeping. (Considerations NOR-DAQmx devices > physical channels > C using DAQmx series explains how the mode of watchkeeping on the NI 9219 is special.) Looks like it is originally calibration null offset NI 9219 acquire separately the calibration offset NI 9235 null data, leading DAQmx to disable all channels on one of the modules, DAQmx handles incorrectly, causing the error.

  It seems that the #198928 CAR should be fixed in the next version of DAQmx. Until then, the workaround is to create separate tasks for execution of the offset null calibration on each module. Note that you can query the AI. Property Bridge.InitialVoltage of each channel to these separate tasks, then set it on every channel in a combined task, so that you can perform your actual purchase by using the combined task. You need only to separate the tasks of calibration offset null real.

  Brad

• Negative results with strain gauges

  When I run my VI the results are always negative. I use the NI9237 with the NI9945. I wired my installation as one quarter bridge. There are three wires from the strain gauge. I went on the wires and I think it's okay / characteristics of NEITHER. Is there something in the MAX that I should be looking. Not sure why the values are negative.

  Thank you

  Harry Stone

  Hi Harry,.

  There are a few things I want to clarify:

  -Traction deformation is positive and compression deformation is negative, what is described a high level in the tutorial below.

  Strain with gauges
  http://zone.NI.com/DevZone/CDA/tut/p/ID/3642

  As strain compression is negative, you would see negative within MAX results if your strain gauge knows any compression. Please keep in mind that a shift can be associated with each transducer, that's why some sensors use a calibration certificate. It is produced by the manufacturer and is provided with the sensor as is the specific sensor. The sensor goes through a testing process to determine its actual response compared to the ideal. In this case, a scale of table can be created to include these values.

  How to do a custom able scale & Automation Explorer (MAX)?
  http://digital.NI.com/public.nsf/allkb/3F6558112FD2C776862575B5004F7F87?OpenDocument

  Not all manufacturers of sensors provide a calibration certificate. Or you can create your own table by placing known quantities of pressure, force, etc. on the sensor and map it to the corresponding voltage, or you can create a linear scale in MAX adjusting the intercept (b) the value necessary to remove any compensation.

  You use the NI 9237 that compensated supports deletion. A null offset is executed with the sensor fixed without load placed on the sensor. Actually, a measurement of voltage is taken and this value is subtracted off the coast of each subsequent measure therefore removing the start offset. This takes up space you creating a linear scale and in doing so manually.

  The two links below show how to use a custom scale created in MAX in LabVIEW, as well as coding the custom in LabVIEW scale to remove the dependency of MAX.

  Acquisition of DAQmx with custom scale
  http://decibel.NI.com/content/docs/doc-3706

  Create a linear scale customized for each channel AI in LabVIEW using DAQmx
  http://decibel.NI.com/content/docs/doc-11136

  I recommend using a task sequence. Input parameters for the information about your strain gauge needed to perform the conversions of strain. There is an example of a measure of deformation in the example Finder LabVIEW (* open LabVIEW * help > find examples) designed specifically for the NI9237 that incorporate deleting the offset and shunt calibration devices. If you do not have external wires connected for calibrating shunt such as cited in this document , you will receive an error. Here is an explanation from the NI-DAQmx help Shunt calibration (start > all programs > National Instruments > NOR-DAQ > NOR-DAQmx help) to help better explain this feature.

  Shunt calibration (adjustment of Gain)
  You can check the output of a measurement system based on a bridge by comparing the measured output bridge with a calculated value if the physical load on the sensor is known. NOR-DAQmx can then use the difference (if any) between calculated and measured values as a factor of adjustment of gain for each measure. You can simulate the application of a load at the bridge by connecting a significant resistance in parallel with the bridge. This resistance, known as a shunt resistance, compensates for the voltage from zero of the bridge. Because the value of the shunt resistance is known, you can calculate the physical load corresponding to the voltage drop of the resistance.

  Use the Shunt calibration perform the Assistant DAQ or DAQmx VI/function to perform a calibration shunt, which defines the the gain setting for a virtual channel. NOR-DAQmx then uses this adjustment of gain when you descale readings from the bridge. Some National Instruments products are internal resistance.

  This may seem like information overload, but I wanted to provide you with a detailed explanation of your understanding, in addition to immediate responses. As a logbook, I recommend that you use the 9237 strain example and use the removal compensation. Negative values are expected for compression and positive for blood. The handy Guide below gives an excellent overview of the strain gauges, which also includes a video.

  Measurements with strain strain gauges: practical Guide
  http://zone.NI.com/DevZone/CDA/tut/p/ID/7130

  Hope this helps!

• amplification of the strain by using the cDAQ

  Hello

  I am a newbie in the use of DAQ hardware and hope someone can help out me.

  I recently bought a cDAQ with the NI 9237 to measure the strains. The strains that I try to measure are very small 1 series micro. A bit of research showed me that I need to amplify the signal to measure these small strains (correct me if I'm wrong). But I'm not able to find amplifiers for the cDAQ.So, the questions I have are-

  1. is it possible to measure these small strains (1 strain micro) using the cDAQ? If so, do I need an amplifier?

  2. If I need an amplifier, are there more specific for the cDAQ with the 9237? If this is not the case, how and where can I get one?

  Thank you

  SID

  SID,

  These results were very shocking for me also, so I looked into it further.  It seems that the 9237 can do better.   Assuming you're within 5 degrees of the calibration temperature (25 ° C), 9237. 05% of span of error and. 05% offset error.  With the range of configuration and 25mV/V full-bridge, you can calculate the absolute accuracy of the 9237 with the following formula.  (Sound of full-bridge = 0.9 microV/V)

  absolute accuracy = (gain error * reading) + (error offset * range) + (noise)

  Do the math, we get

  25mV/V + / 25.9 microV/V

  In a full-bridge configuration: V/Vex =-(Gauge Factor) * strain

  
  

  With a typical GF of ~ 2.0, we can say that the accuracy of the strain will be

  12.5 mm/m + / microm 12.95/m

  It's a little more in the range that you hoped for.  Sorry for the confusion.

  If this does not work for you, we sell solutions PXI who will be able to measure more precisely.  Similar math help and type of configuration of full-bridge with SMU 4330 plug, we get:

  12.5 mm/m + / 3.48 microm/m

  In my view, that it is card data acquisition based on a bridge more precise and accurate that we sell.  It requires a controller/chasis PXI.

  Please let me know if you have any other questions!

  Sincerely,