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NI OPC Server for CompactDAQ - unreliable

January 7, 2017, 6:09 am
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Hi,

We have been using NI Compact Fieldpoint devices with the "National Instruements.OPCFieldPoint" OPC server for many years without a single failure. However, due to their obsolescence we have been forced to use CompactDAQ along with the "National Instruments.VariableEngine" OPC server. Since then we have had many occasions when the OPC server just stops communicating with the modules and the only way we have managed to restart it is to carry out module self-test in Application Explorer - even cycling the power does not help! This has happened on all three of our installations at different times. Has anyone else experienced this and have a resolution?

 

Thanks,

 

Tony

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Analog Input NI USB 6009

January 9, 2017, 8:13 am
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I am using a USB 6009 differential analog input channel to read a voltage from a load cell amplifier. I am however unsure if it is ground referenced or floating signal output. The power supply to the amplifier is 24Vdc and grounded. The output is +-10Vdc but not sure if floating/isolated. I have measured resistance from power supply negative to signal output negative terminal and have a reading of 5 MOhms. Can i presume the output is isolated from ground?  If I cannot determine which is correct should i use a floating or ground referenced connection as default?

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DAQmx base 15, Linux, OpenSUSE 13.1 and USB-6259

January 9, 2017, 10:59 am
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Hi NI Gurus,

 

Can anyone tell me why the PCI-6259 is compatible with OpenSUSE 13.1 and DAQmx Base 15 but not the USB-6259 version? If it is compatible, can you please tell me how to make this work?

 

I have got all the NIKAL, NI-VISA and DAQmx Base code to work in OpenSUSE 13.1 but it will not recognise the USB-6259.  It will recognise other boards on the compatible list from NI on the DAQmx Base 15  (http://www.ni.com/download/ni-daqmx-base-15.0/5644/en/)

 

Best, Trevor

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Controlling solenoid valves with PCI 6289

January 9, 2017, 2:49 pm
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Hi,

I have 3 solenoid valves(2 way, NC) that I have to control via PCI 6289. I know I have to write a Digital signal to a relay to energize it with 12 VDC with a daqmx write function. The use a Queued Message Handler design pattern to turn ON and OFF the valves with corresponding buttons. 

 

If I click a button to turn on a valve, the corresponding case structure executes and data is written, and now try to open another valve, another case executes. Does this mean the previous valve does not receive power anymore since that case exited?

If so, how can I change the architecture to keep three valves open at the same time?

 

 

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Long duration data acquisition with USB-6002

January 10, 2017, 1:09 am
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Hi,

I'm using a USB-6002 DAQ card to take measurements for a fatigue test. The test is supposed to last for 3 months without interruption. The data acquisition is set to Finite Samples with a sampling rate of 1kHz and taking 100 samples. This acquisiton task is set inside a main loop which executes every two seconds. The problem is that after 3 to 5 days of testing the USB6002 stops working correctly and instead of taking the measurements in 0.1 seconds it takes 15 seconds and sends an error. I have reproduced this error in different computers, with and without sensors connected to the DAQ card and with different USB-6002 cards, always after 3 to 5 days of continuous testing, and the only solution is to disconnect the usb cable and connecting the DAQ card again.

 

Is it possible that the USB-6002 isn't capable of working continuously for a long period of time? Or is there any ideas of where this problem may come from?

 

Due to confidentiality reasons I can't upload the complete code but I attach the acquisition subVI.

 

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DAQ acquisition

January 10, 2017, 5:22 am
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Hi everyone,

 

I am using a 9188 cDAQ and I'm acquiring more signals at different rate using DAQmx functions. I would like to get the measurements synchronized and be able to create an XY graph with correlated signals in order to know what was the value of one measurement when another one is at a certain value. I don't really know how to do that synchronization; for now I'm using a while loop for every signal to read an array of different lenght, couse I don't want to stress the PC with a buffer too wide. I thought I could write also timestamp in the acquisition, and use interpolate function to set a signal based on other signal's time, but then I don't know how to correlate them at last.

Does anyone know how can I do that?

Thank you very much for your attention.

Best regards 

 

Francesca

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Installing NI-DAQmx on windows 10 not working

January 11, 2017, 6:55 am
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I have a PC running Windows 10 Education on a 64-bit computer. When I download NI-DAQmx 16.1.0 and try to open the installer I just get the error message 'This app can't run on your PC'. Any ideas what's wrong?

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DAQ Suggestions for analog input and output for lab setup

January 11, 2017, 8:15 am
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Hello, 

 

Here's my setup: I have six pressure regulators that allow me to output pressure between 0-20 psig. These regulators have a control signal driven by analog voltage 0-10 V, and a monitor signal analog voltage 0-10 V. The monitor signal allows me to read out what pressure was actually output compared to the desired pressure. In my experiment, these pressure regulators are part of a feedback control loop, where the loop is driven at frequency of 30 Hz (I might be shifting to a higher frequency in a future ~100 Hz). Thus, the pressure needs to be updated every 33 ms (or lower in the future). I'm looking for NI hardware that can allow me to output and read 6 analog voltages at this loop frequency. The feedback voltage is calculated on a computer inside a labview program. The analog input will be used just for monitoring the actual pressure that was applied and will not be used for calculating the feedback pressure.

 

After browsing the website, I've shortlisted the following options:

1. NI USB 7845R + SCB-68A + SHC68-68-RMIO Cable 

2. NI PCIe-7841R + SCB-68A + SHC68-68-RMIO Cable 

3. NI cDAQ-9174 + NI 9201 + NI 9264

 

I was looking for feedback on these options regarding advantages and disadvantages, and other factors (for eg. USB vs PCIe) that I should consider. I'm also open to alternative configurations that serve the same process.

 

Thanks!

 

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Linux NI-DAQmx Base 64-bit application support?

January 11, 2017, 11:07 am
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I'm running Scientific Linux 6.x developing custom applications that utilize data transmitted/acquired via PCI-6259 cards. Recently the application is approaching the 3.5 or so gig RAM limit with 32 bit applications. We're using NI-DAQmx Base 3.6.0 installed in fall of 2012 so I figured maybe there was a newer version of the driver that supported 64-bit applications. It appears that version 15 (the most recent version for Linux) still does not. I noticed that NI-DAQmx 16.1 for Windows does support 64-bit applications, though. Does anyone on here know the time-table for release of a driver with 64-bit application compatibility for Linux? 

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USB 6009 analog output

January 12, 2017, 7:57 am
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Hi all,

 

I am working with an NI USB-6009 to generate an analog output voltage via Matlab. There are two analog output channels (AO0, AO1), but I can only get one of them to work. For AO1, I can easily set any voltage between 0 and 5 V, and it responds exactly as I would expect. For AO0, the voltage is constantly at 0.3 V, regarless of what voltage I set in software. At this point I am assuming that some internal component has blown out on that channel and I'll probably have to replace the whole board, but before I do so I wanted to see if there may be some behind-the-scenes parameter that I could have overlooked that may be preventing me from updating the voltage. Below is an example of the Matlab code that has worked succesfully for AO1 but does not work when I switch to AO0.

 

onVoltage=4;
offVoltage=0;
s=daq.createSession('ni');
addAnalogOutputChannel(s,'dev1','ao1','Voltage');
outputSingleScan(s,onVoltage)
pause(3)
outputSingleScan(s,offVoltage)

 

Thanks in advance for any suggestions.

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sbRIO9637 not seen by NI MAX

January 12, 2017, 8:59 am
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Dear colleagues,

I have been developping a system based on this particular board. Everything worked fine until I moved the system from one table to another. After this step I cannot connect to this board. In MAX I see as if it was disconnected. I tried to replace the ethernet cables, but without any effect. Both LEDs on the board ethernet connector side are lit. Right LED is green (100Mbit/s) and the left one (ACT/LINK) sometimes blinks. Status LED panel on the board has only the leftmost LED ON (POWER ON).

Do you know, what could potentially happen and how can I diagnose the fault?

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Synchronizing different DAQ cards

January 12, 2017, 9:49 am
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I have a PXI-4472B and a PXI-6289 card and would like to acquire synchronized data from the two. The examples for synchronizing e.g. the analog input of multiple DAQ cards which I found all assume that one uses the same type of card but here I am mixing M series and DSA.

So before diving into this: Is that possible at all or are there any limitations here?

 

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Selecting PWM and AI/DI/DO DAQ Module

January 12, 2017, 11:45 am
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I am looking for a DAQ module that has one channel for PWM generation, and other channels with AI and DI/DO. Any suggestions?

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Generating 1 Digital Pulse Train + 4 Analog Pulse Trains (with Custom Amplitude)

January 12, 2017, 9:58 pm
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I have the following hardware setup and was hoping for some advice on how to approach pulse train generation with my DAQ (USB-6343).

 

I have a TTL input coming into my DAQ.  When I see a rising edge, I would like to generate:

  • 1 Pulse Train to a Digital Out with 1,000 Pulses, at a Frequency of 1 kHz, Duty Cycle of 0.5.
  • 4 Pulse Trains, each to an Analog Voltage Out, with 1,000 Pulses, at a Frequency of 1kHz, Duty Cycle of 0.5.  The "low" value of the pulse train should be 0V, and the "high" value of the pulse train should be some constant pre-set value (between 0-2V).

These pulse trains should all by synchronized to trigger when the TTL input sees a rising edge.

 

I have figured out how to do the first part, which is to generate a pulse train to a Digital Out by using a counter.  However, I had a few questions about the 2nd part:

 

  1. What is the best way to generate the analog pulse trains?  I found this VI (http://www.ni.com/example/29787/en/) but am not sure exactly how it works.
  2. Is it possible to use the same TTL input as the digital edge trigger for both the Digital Out and the Analog Voltage Outs?
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Confusing behavior with DAQmx read (USB 6001)

January 14, 2017, 4:03 am
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I'm having trouble figuring out how to perform continuous analog input using DAQmx.   I am using a USB 6001 with Windows LabVIEW 2015.

 

I would like to read a single analog input channel continuously at 1 kHz.  I configure the channel for continuous reading with a sufficiently large buffer, then start the DAQmx task before entering the read loop.  During each iteration, I first do some other I/O, then I try to read all the analog samples that have been buffered since the last read.  The other I/O takes a variable amount of time, but never long enought to overflow the DAQmx channel buffer.

 

The problem I'm encountering is that, the first time I try to read the analog input buffer, I get an empty data set  -- no matter how long it's been since I started the task.  Then, the next time I try to read the data, I get the data that should have been returned the first time!  There are no errors, but the data is always one cycle out of date.

 

For example, let's say that after starting the task, I wait 5 seconds before attempting to read the the buffer.  I read zero points.  If I then try to read again after 1 second, I will get approx. 5000 points.  Then the third read will be approx. 1000 points, no matter how long I wait before performing it.  

 

The attached VI exemplifies this beavior.  Here, the read attempts are timed by pressing a front panel button.  It is easy to see the problem by looking at the approximate number of samples returned per millisecond of read interval, which should be ~1.

 

I've tried changing many DAQmx channel/read/timing/etc settings, and also several ideas from these forums, but am still stuck.  I'm sure (or at least hope) that someone will point out an obvious error with my approach.  The only thing I've found that affects this behavior is that, if I regularly poll the AvailSampPerChan property between reads, the data lag goes away for the second and subsequent reads.  The first read is still missing some (but not all) of the data -- and it only works if I am almost constantly polling the AvailSampPerChan property.  For example, polling it once, right before the read, doesn't help.  

 

Is there a flow-driven way to consistently read "fresh" analog input data with DAQmx?

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Sending a byte to a digital output using a VI

January 16, 2017, 6:20 am
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Hello,

Since i'm new to LW, i would like some help and advices on something using a USB-6002 NI DAQmx.

 

I would like to setup a digital potentiometer (MCP41100) and for that i need to send the correct data as a byte, in serial, so it could be configured correctly. My problem is, i don't see how to "transfer" the byte into the component trough a digital I/O of the USB-6002. Which function can i use ?

 

Thanks for your help

 

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NI DAQ 6321

January 16, 2017, 7:36 am
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Hi , i am a new member in NI-COMMUNITY and im planning to buy a NI DAQPCIe-6321 X-Serie device  from : http://sine.ni.com/nips/cds/view/p/lang/en/nid/207405 .  I'm wondering if they Offer with this card the BNC connector or not, and if not which one should I buy: BNC 2100 or BNC 2110

thanks in advance.

 

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PCI-6733 Self-Test Failed

January 17, 2017, 7:07 am
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Hi guys,

 

I'm using a PCI-6733 card with Windows 7 and NI DAQmx 16.0.1. I recently noticed that it is not outputting any voltages. In NI-MAX, there is an error message that the self-test failed (error code -200020). I recently updated the NI DAQmx for compatibility with newer USB boards, could the new software be incompatible with the PCI-6733 card?

 

Thanks in advance

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Uncertainty Analysis for C Series Modules

January 17, 2017, 1:12 pm
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I am interested in to GUM style error analysis (Type A, Type B) for measurements for voltages (NI 9219) and temperature (NI 9214). I have consulted NI Applications Engineering concerning Absolute Accuracy (AA) for a different NI DAQ device.  The NI 9214 and NI 9219 also specify AAs.  Yet looking for as much information as possible before asking for the same question, I came across the following documents:

 

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

 

http://www.ni.com/white-paper/4517/en/#toc3

 

I also found a GUM uncertainty budget for the NI USB-568x:

 

http://www.ni.com/tutorial/6785/en/

 

In the USB-568x uncertainty tutorial it states: “Absolute uncertainty percentages are not included in the specifications documents of NI USB 568x RF power sensors”.  Thus, the need for an uncertainty analysis. 

 

In the GUM analysis all errors are assumed to follow a distribution, so the idea is to determine the appropriate distribution and the confidence level/coverage factor to determine the standard deviation or standard uncertainty. With my previous contact with NI,  I was thinking it would be reasonable to assume the AA could be approximated as normally distributed uncertainty with a coverage factor of 3 because the noise error is multiplied by a coverage factor of three before adding it to the AA. 

 

With this additional info, I am seems my intial assumption maybe wrong and the AA could be a correction I need to apply to the readings from these DAQs.  Either the error in this correction is unknown, negligible, or perhaps not applicable. If I want a correction with an uncertainty, then I would probably what NI calls a system calibration.  The GUM analysis is suppose to be able to determine and propergate errors in measurements of any complexity, so AA should come how be included.  Even other methodologies require the errors to be of the same type before being combined, usually by Root Sum of the Squares.

 

Thank You

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Parallel ports, the USB 6501 IO board & C++

January 18, 2017, 12:43 am
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Hello,


I have some equipment I would like to send digital triggers to via the parallel port. My issue is that 64-bit Windows 7/10 seems to lack drivers for doing that. Another option is to use a USB->parallel port device. The one I am currently looking at is:

 

http://www.cortechsolutions.com/Products/SD/SD-MS/SD-MS-TC/001114

 

It apparently has a National Instruments USB 6501 OEM IO board and from what I can tell I would use NI-DAQmx to program it. From this readme http://download.ni.com/support/softlib//multifunction_daq/nidaqmx/16.0.1/readme.html it seems that later versions of Visual Studio are not supported. C++ is not mentioned either.

 

What I want/need is to include/link a 64-bit program/library, without any GUIs or large frameworks, that can be used/linked by Unreal Engine(64-bit and latest Visual C++(2015)). Can I use the 6501 for this purpose or do you have any other suggestions?

 

Cheers,

Daniel

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