SCXI-1125 overvoltage criterion

Hello all,
I am going to use a SCXI-1125 module with SCXI-1327 terminal block to condition thermocouple signal. Estimated signal range is about 0-50mV.
The problem is, since the thermocouple bead must be attached directly to a resistance heater, on which current flows at 100Hz with certain duty cycle, it is expected that part of the heating voltage(no more than 1V) will be imposed on the thermocouple bead. We can manage in LabVIEW so that no overlap exists between data acquisition and heating.
I use an oscilloscope to measure the voltage from the thermocouple wires. Surprisingly, at the end of each current pulse, there seems to be a negative peak voltage. The duration of the peak is about 0.02ms out of every period, which is 10ms. Magnitude of the peak varies between 1V to 20V.
I look into the manual of SCXI-1125, which says when measuring voltage larger than 5V the 100:1 attenuator on the terminal block (for example, SCXI-1327) should be applied. But when I tried this way, the temperature signal suffered from large noise, maybe due to its very low nature.
If I bypass the 100:1 attenuator, is there possibility to damage SCXI-1125? I wonder whether the peak voltage or the continuous voltage should be avoided. The manual doesn’t provide parameters such as “input current during overvoltage condition”.
Any suggestion would be greatly appreciated.
Su

Lynn,
Thank you for your very fast reply. In fact our heater was fed by two 12V lead-acid batteries in series and the averaged power input is ragulated by an IGBT module, and the two electrodes which stretches the heater are floating-connected rather than grounded. The thermocouple wires are also ungrounded.
During the run, I think there is no large external interference(such as a welding machine or other on/off operated device) nearby. Once I recharged the batteries beside the apparatus and interference as large as 1 V appeared. In other case no descernable random interference seems to exist.So maybe the problem is from the inner of our device?
The png file named "nonoverlap" shows the voltage signals every 50 samples for a period, during sampling no current flows. The png file named "temp" is the temperature signals corresponding to the previous voltage signals, every data is the result of the average value of the 50 samples mentioned above. The last file named "interactive" is the voltage signals every 150 samples in a period, with each last 100 samples overlapping with the heating pulse. You can see two peak signals in the beginning (the data before the first negtive peak come from a previous run).
Best regards,
Su
Attachments:
Nonoverlap.PNG ‏50 KB
Temp.PNG ‏31 KB
Interactive.PNG ‏35 KB

Similar Messages

  • Need to be Able to use a TB-1328 with an SCXI-1125

    I need some labview code to show me how to read temp from a SCXI-1125 with a TB-1328 thermocouple on it. I have a K type thermocouple wire, I have to stick with Labview V7.0, NI-DAQ 6.9.3f5, and this is running on an RT machine using a PXI-1010 split PXI/SCXI chassis, with a PXI-6040E running the SCXI bus. Please if you could, tell me how to remote DAQ configure this. Thank you.

    Hello,
    If you have NI-DAQ 6.9.3 support installed for LabVIEW 7.0, then you should have an example which will show you how to acquire a thermocouple reading from a SCXI-1125. The example which I am referring to is called "SCXI-1125 Thermocouple.vi". Regardless of what terminal block you are using with the SCXI-1125, you need to make sure that you configure it accordingly in Measurement and Automation Explorer.
    For assistance with Remote DAQ configurations, please refer to the following knoweldgebase: What Do I Need to Know to Set Up My Remote SCXI System?
    Regards,
    Jared A

  • SCXI 1125 self calibration

    Hi,
    Does SCXI  1125 support self calibration? If yes, can I do it using the DAQmx Self Calibrate.vi?
    "A VI inside a Class is worth hundreds in the bush"
    യവന്‍ പുലിയാണു കേട്ടാ!!!

    Thank you Vishal.
    SCXI 1125 user manual says that internal calibration is possible (for offset) and that we should use the SCXI calibration VI (not the DAQmx Self calibration VI). I am not able to find this VI in the DAQmx Calibration palette. The only SCXI calibration VI present is for external calibration.
    "A VI inside a Class is worth hundreds in the bush"
    യവന്‍ പുലിയാണു കേട്ടാ!!!

  • Need continuous acquisition of 16 channels through SCXI-1125 to PCMCIA DA board + FFT on all channels. Can it be done?

    Where's the limit? Assume a new Dell Latitude running NT with 128 MB RAM and a fast P3. Equip it with the DAQCard-AI-16E-4 connected to an SCXI chassis with 2 SCXI-1125 modules.
    How fast can I run the sample rate (per channel) if I want to do continuous DAQ on all 16 channels while computing the power spectrum of all channels once per second (using one second's worth of samples)?
    The DAQCard has a tiny FIFO, and I'm hoping to use pretriggered scans so I don't have to wait for data. Is that an option without the DMA functionality of the PCI E-Series boards? Without it I will have to constantly empty the FIFO into a "software" b
    uffer which will cost boku (many) processor cycles, correct?
    So what say the experts... how fast can this thing run? How about if I ditch the laptop and go PXI with the whole deal? Lets make the case!
    Thank you!

    I believe the PCMCIA interface is going to be the limiting factor in this case. The maximum continuous rate for a DAQCard will vary from computer to computer, but it isn't extremely fast.
    Being optimistic, let's estimate 64 K samples/second. I don't know if this is high or low nowadays, but it is higher than I could ever achieve a couple of years ago. Divide that by your 16 channels, and you have 4K blocks. I think you could process this in 1 second easily. This gives you 1 Hz resolution up to 2 Khz.
    Now, if you ditch the laptop and go to PXI, it is a whole different story. DAQ rates will not be the limiting factor. You just need to find out how large of a block you can process and keep up.
    My approach to this problem would be to figure out what analysi
    s you need, then figure out what hardware can accomplish it. Do you really need 1 Hz resolution? Do you need to process every bit of data that comes in? Are you going to store the results, or just display them on the screen? Can you do post-processing of the data if necessary?
    Bruce
    Bruce Ammons
    Ammons Engineering

  • SCXI-1125 スケーリング

    ご教授下さい。
    SCXI-1125にSCXI-1320を接続してあります。
    MAX5.0で電圧入力、GAIN=1に設定したチャンネルで、
    スケールなしのテスト表示では問題なく４V程度を計測できているのですが、
    スケールで５V未満までの表を設定すると、入力範囲上限が2.5Vになり、
    それ以上は2.5Vのスケール値でクランプされてしまいます。
    何が問題で上記のようになってしまうのでしょうか？
    解決済！
    解決策の投稿を見る。

    TAKINAMI様
    ご返信頂きましてありがとうございます。
    こちらでは、NI DAQｍｘが提供する「表スケール」の動作を確認致しました。
    指定された値がきちんと反映され、特に問題なかったです。
    「表スケール」にて信号の入力範囲は、0V-5Vに設定できないでしょうか。
    カスタムスケールを「線形」にして頂いた場合の測定結果はどうなりますでしょう。
    表スケールの詳細は下記の通りになります。ご確認ください。
    表スケール
    表スケールを使用して、プリスケール値の配列を対応するスケール後の値の配列に割り当てます。これ以外の値​はすべて比例的にスケールします。
    たとえば、以下の表スケールを構成するとします。
    プリスケール値: 0, 5, 10
    スケール後の値: 0, 10, 20
    入力操作の場合、デバイスが2というプリスケール値を集録した場合、読み取られるスケール後の値は4になります。出力操作の場合、2というスケール後の値を書き込むと、デバイスは値1を生成します。

  • SCXI-1125: what kind of A/D Converter structure?

    Hello,
    Im a student and actually Im writing my diploma thesis.
    For this I need some information about the SCXI-1125.
    What kind of structure does the A/D Converter have?
    What is the resolution of the 1125?
    How many Bits does it have?
    What ist the accuracy of the CJC sensor?
    All other additional information about tht 1125 could be helpfully, so kindly help.
    Best regards
    Christian

    Hello Christain,
    The SCXI 11125 user manual that you shall find here should help you
    Mind you, SCXI 1125 is only a signal conditioning module
    You need to interface it to a suitable DAQ card for any A/D conversion and that DAQ card's A/D architecture, resolution etc shall be your determining factors
    Regards,
    Dev

  • Scxi 1125 R202 getting burned

    Wondering if anyone else has seen this issue.
    I have about 200 of these cards (SCXI-1125) in service in production test machines.  Quite a few of the failed units have R202 burned on the SCXI-1125 card.  Sometimes replacing R202 fixes the issue, but more often it does not.  Since i do not have a schematic of the 1125, it is hard for me to tell if this is a design flaw, or if it is something that we are doing.  Luckily, I also have a stack of 32 of these cards that were purchased for a project that was cancelled, so spares is not an issue thankfully. 

    We are testing power supplies, specifically DC to DC converters.  So yes, static DC voltages.  We are also reading static DC voltages from the analog controls of some of the other instruments in the rack (power supplies and loads).  At no time is there more than +10V present on any channel.  These being 8 channel devices, I would find it strange that we are only seeing damage to one component.  As far as I know, the way we have it cabled, we are using all 8 channels separately and using the mux in the 6031e card to channel the readings to the AtoD.
    So I would like to know the purpose of R202 in the circuit of the SCXI1125?

  • SCXI 1125 lowpass filter

    Hello I am using a SCXI 1000 chase with two SCXI 1125 cards. My question is how can I configure a software filter that works like the one implemented in the SCXI 1125 card. More exactly i what to build a 4 Hz cuttoff lowpass filter. Thank you. 
    Attachments:
    filter.jpg ‏139 KB

    Which module are you using?
    I suppose you could always just run your signal through the Filter express VI (in the Express » Signal Analysis palette) or one of the VIs on the Signal Processing » Filters palette.
    Kyle B  |  Product Support Engineer  |  ni.com/support

  • SCXI-1125 scan rate controlling

    SCXI-1125 scan rate is 333kHz in the multiplexed mode. Does anyone knows how to slow the scan rate?.
    regards.
    naushica

    According to the web page "http://digital.ni.com/public.nsf/allkb/410A70C25A4D12B486256A1E0070BDAE"
    You will lose resoltuion for increasing the scan rate.  Isn't it?
    If the scan rate is 100kS/s and the input range is +-5V  with the
    14bit resolution, does that mean  that  I have a
    noisefloor of 600uV for that range?
    If I want to measure a signal in +-1V range does that means the noise floor is around 120uV?
    The absolute accuracy table on the other hand states about  an accuracy full scale range but
    doesn't state about scanning speed.
    For example, 18-bit  ADC module PXI-6289 data sheet states that +-5V range has a full scale
    accuracy of 510uV.If  converted to bits, it will be less than 15bits.
    So even though I reduced the scanning speed to abt 50kS/s will I get an accuracy of 16bits?
    I have a SCXI-1125 + PXI-6289 installed in a PXI-1052 combo chassis.
    Please help on this matter.

  • Noisy thermocouple signal with SCXI-1125

    Hi all
    Am using SCXI -1125, with 1328 terminal blocks, I have set the filter to 4hz in the signal conditioner. Am using 256 T type thermocouple, with 1 sample per channel at a very low sampling rate "1Hz".
    Am receiving lot of noise in the signal, aprox +/- 1deg. But there are other channels which are very stable with hardly 0.2deg variation. I have tried connecting the negative of the noisy signal to ground, but with no results. Can anyone give some input on this?
    Thanx a lot
    Arun

    Arun,
    Are you sure you are setting these properties correctly? Before
    modifying any of these properties, you must specify the active
    channels. Please take a look at the attached example program. It sets
    the active channels to all channels in the task and then sets the
    auto-zero mode. A similiar process should work for enabling the filter
    and setting the cutoff frequency.
    Hope this helps!
    Ryan Verret
    Product Marketing Engineer
    Signal Generators
    National Instruments
    Attachments:
    Cont Acq Thermocouple Samples-Int Clk.vi ‏98 KB

  • Error 10810 occurs when running with SCXI

    Iam running an LV example program in RT(PXI-8176,Daq Device PXI-6052E)and i have a SCXI 1520,seven 1125 & one 1102b modules in my SCXI Chassis.When i run example acquisition program iam able to acquire from module 1 & 2(i.e 1520 & one 1125)but from my 3rd module to the rest of modules i'm not able to acquire.I get an error saying that "Error-10810 unexpected error in Group config" what could be the reason?

    Hello,
    The problem is probably related to a conflict between the driver and the controlling module in your SCXI chassis. I have heard of this problem before when trying to acquire data from an SCXI-1125 that is slot 3 or higher of a SCXI chassis running in RT, and it resulted with that exact error.
    There was no fix such as upgrading to a newer version of the driver or anything like that. Rather, the problem was shown to occur only when the SCXI-1125 module was used to control the SCXI chassis. If they used any module other than the 1125 to control the chassis, then there was no problem.
    My suggestions to you are to try this exact thing - do not use an SCXI-1125 module as the controller for your chassis. If this doesn't happen to be the case, or this does not
    work out for you, then please post back to this discussion so we might be able to solve this problem. If you happen to post back, please list some more information such as driver version, OS, SCXI chassis, controlling module/slot, etc.
    Best of luck.
    Jared A

  • Why does SCXI 1325 give a NaN output at all channels?

    Till yesterday SCXI 1125 was working fine. But today the values that I am getting from all its channels is "NaN". No error is given.
    When I tried running the Test Panels thru NI-MAX, SCXI 1125 still gave a NaN output, while 6040E, 6251 and SCXI 1142 did not.
    Can someone tell me what is the problem and how it can be rectified?
    Setup :
    PXI chasis consisting of PXI 6040E and 6251
    SCXI 1000 chasis consisting SCXI 1142 and 1125
    Connection to SCXI 1000 chassis is thru PXI 6040E
    PXI 6040E connected to SCXI 1142 (accessory SCXI 1304)
    PXI 6251 connected to SCXI 1125 (accessory SCXI 1313)
    Data collection thru Parallel mode
    Thanks
    Jag

    Thanks Kodee for your reply.
    Well this is what I have done so far :
    a) Removed all the SCXI modules and reconnected them. Checked the wiring.
        But still get the same result "NaN" for SCXI 1125
    b) Reinstalled DaQmx drivers
         Still the same NaN result for SCXI 1125
    Also I have now realised that when I try to measure an analog signal thru the module SCXI 1142, I get some varying signal initially followed by a steady 5V signal.
    I am not sure whether this fault was present yesterday when I first came across the NaN problem with SCXI 1125.
    So right now, SCXI 1142 gives a steady 5V output while SCXI 1125 gives a NaN output.
    Could you suggest what I should do next?
    Also in your reply you had asked me to check whether any printer drivers are interuppting NI drivers. How can I check that out?
    Thanks
    Jag

  • How to set the jumper for scxi 1140?

    Hi, I would like to connect the SCXI1140 module to PCI 6052E.SCXI1140 is connected  to SCXI 1125 by the cable SCXI 1325 to get the data from SCXI 1125. I could not well understand the suitable configuration  for W9, W10,W11, W12, W13 and W14 jumpers in  SCXI1140. would you please help me out?

    Hello, 
    First, can you please verify that you are using the SCXI-1352 cable and not the SCXI-1325 teminal to cascade the SCXI-1125 to the SCXI-1140. Here is a link about cascading SCXI modules and here is the link developping your particular case of cascading the SCXI-1125 to the SCXI-1140. You can see that the configuration of the jumpers depends only on your application. This link  to the User Manual of the SCXI-1140 should give you the configuration you have to make depending on your application.
    I hope this will help you.
    Charlotte F. | CLAD
    National Instruments France
    #adMrkt{text-align: center;font-size:11px; font-weight: bold;} #adMrkt a {text-decoration: none;} #adMrkt a:hover{font-size: 9px;} #adMrkt a span{display: none;} #adMrkt a:hover span{display: block;}
    >> "Du 11 octobre au 17 novembre, 2 sessions en parallèle : bien démarrer - approfondir vos connais...

  • Reading Data from SCXI 1600

    Hi Experts,
    I am new to this SCXI Interfacing. Kindly help me in the context
    I am developing an application which is going to be use  SCXI 1125 module and SCXI 1600 controller.In the application I want to allow the user to configure various Task in the front panel. 
    What are the controls needed in the front panel to allow the user to configure Task 
    How to read the data from SCXI 1600,
    How to differentiate eight channel data coming from SCXI 1125 thro SCXI 1600
    Thanks in advance
    Solved!
    Go to Solution.

    True, you cannot simulate the SCXI-1600. This means you will not be able to run your code without the hardware. For simulation purposes you can, however, use another device that would function in a similar manner to the SCXI-1600 in terms of triggering, resolution, and sampling rate.
    As for the programming, you would use DAQmx as I had mentioned. There are no examples that are specific to the SCXI-1600, but you don't really need them. The SCXI-1600 is fundamentally a data acquisition module that happens to be in a SCXI form factor with a USB connection. As far as your software is concerned you will use DAQmx to read data from it. So, take a look at the DAQmx examples that gather data from data acquisition devices.
    Your task will define how many channels you will be reading. Since you are reading a mixture of measurements (temperature, pressure, and possibly just plain voltages) you will need to decide whether to create separate tasks for each of these measurements that are configured to be specific to that measurement type, or to create one task that simply reads all unscaled channel values (i.e. raw voltages) and then you scale the values in your code. If you open the Example Finder and navigate the tree to Hardware Input and Output -> DAQmx -> Analog Measurements you will see categories for the different measurement types. Many of them have graphs. 
    If you have not already done so, you may want to start here: http://zone.ni.com/devzone/cda/tut/p/id/3116

  • Cannot configure SCXI 1102 in parrallel mode

    Hi all...
    I have a little problem, i have a system made of 3 Daqmx cards : 2 PXI-6254 and 1 PXI-6229. these cards are linked to SCXI modules. The acquisition of the data are done in parrell i.e. the first PXI 6254 is linked to 2 SCXI-1125, the 2nde PXI-6254 is linked to one SCXI 1125 and one SCXI 1102B and the third one is linked to one SCXI 1180 and one SCXI 1102...
    So i defined 3 different Daqmx Task in MAX (one for each DAQmx card) and i configured the SCXI rack.. but when i try to configure the SCXI 1102 B or the SCXI 1102  i CAN'T choose the parrallel mode i can only choose multiplexed mode... and therefore, when i run my application, i have the following error:
    Error -200619 occurred at DAQmx Start Task.vi:6
    Possible reason(s):
    Measurements: Chassis cannot be used for more than one scanning operation at the same time.
    Do only one scanning operation, or combine multiple scanning operations into a single operation.
    Can't anybody explain me why ???
    Thanks a lot for your futures answers ...

    Not necssarily, You can have parallel mode for other SCXI modules while acquiring from SCXI 1102 in multiplexed mode
    See this Link

Maybe you are looking for