Ni pxi 6221 daq card internal dc offset is appearing in every signal
sir ,
thank u for the quick response from ni , please reply for my first
question , i.e there is internal dc offest value of around 0.35 volts
appearing with every signal when i try to measure it with a pxi 6221
multi fuction daq card and ni elvis oscilloscope or oscilloscope
to observe it . even though the the dc offset is zero from the
source side (arbitray waveform genertor).
Deepak Kumar
M.Tech , Power and Energy Systems
NITK SURATHKAL
MANGALORE
INDIA
Hello,
What is your arbitrary waveform generator's product number? Have you tried calibrating the arb?
Regards,
Sean C.
Similar Messages
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I'm using the MHDDK for analog out/in with the PXIe 6341 DAQ card.
The examples, e.g. aoex5, show a single Timer (outTimerHelper::loadUI method), but the example shows DMA data loaded with the same vector size.
There is a comment in the outTimerHelper:rogramUpdateCount call which implies that different buffer sizes per channel can be used.
(the comment is: Switching between different buffer sizes will not be used)
Does anyone know what the format of the DMA buffer should be for data for multiple channels with different frequencies ?
For example, say we want a0 with a 1Khz Sine wave and a1 with a 1.5Khz sine wave. What does the DMA buffer look like ?
With the same frequency for each channel, the data is interleaved, e.g. (ao0#0, ao1#0; ao0#1, ao1#1, ...), but when the frequencies for each channel is different, what does the buffer look like ?Hello Kenstern,
The data is always interleaved because each card only has a single timing engine for each subsystem.
For AO you must specify the number of samples that AO will output. You also specify the number of channels. Because there is only one timing engine for AO, each AO will channel will get updated at the same time tick of the update clock. The data will be arranged interleaved exactly as the example shows because each AO channel needs data to output at each tick of the update clock. The data itself can change based on the frequency you want to output.
kenstern wrote:
For example, say we want a0 with a 1Khz Sine wave and a1 with a 1.5Khz sine wave. What does the DMA buffer look like ?
With the same frequency for each channel, the data is interleaved, e.g. (ao0#0, ao1#0; ao0#1, ao1#1, ...), but when the frequencies for each channel is different, what does the buffer look like ?
In your example, you need to come up with an update rate that works for both waveforms (1 KHz and 1.5 KHz sine waves). To get a good representation of a sine wave, you need to update more than 10x as fast as your fastest frequency...I would recommend 100x if possible.
Update Frequency: 150 KHz
Channels: 2
Then you create buffers that include full cycles of each waveform you want to output based on the update frequency. These buffers must also be the same size.
Buffer 1: Contains data for the 1 KHz sine wave, 300 points, 2 sine wave cycles
Buffer 2: Contains data for the 1.5 KHz sine wave, 300 points, 3 sine wave cycles
You then interleave them as before. When the data is run through the ADC, they are outputting different sine waves even though the AO channels are updating at the same rate. -
Im using a pci-6221 daq-card.I want to know the difference(use)of a line output and a port output.
Im using a pci-6221 daq-card.I want to know the difference(use)of a line output and a port output.
Hello Hellraiser24,
This question has actually been discussed in another thread here:
http://forums.ni.com/ni/board/message?board.id=170&message.id=95895&requireLogin=False
I hope this helps,
E.Lee
Eric
DE For Life! -
How to use PXI 6071E daq card to complete multichannels scan with high sampling speed
I used pxi 6071E daq card to acquire 115v 400hz AC signals.when I use mutichannel scan function,I find that the voltage of waveforms have much more error.The voltage error is about 0~15v.please you can tell me why this happened?how to solve it.
Attachments:
多通道监测4.vi 199 KBSunny;
As you are scanning multiple channels and the signal range is high, you can try to set the interchannel delay a little higher. The interchannel delay is the time which the multiplexer will take to switch to the next channel. If that time is to short, the instrumentation amplifier can have problems to settle, and then an error at the reading will happen.
You can change the Interchannel delay at the AI Config.vi.
Hope this helps.
Filipe -
DAQ Card is inducing noise on an external clock signal resulting in false triggering
I am using an optical encoder as an external clock source for analog measurements with a PCI 6036 card. The optical encoder signal is "filtered" using a Schmitt Trigger circuit and proper shielding practices are used on the encoder cable. I am using a recent version of Labview.
When the TTL square wave signal from the encoder is viewed on an oscilliscope (without the DAQ attached) it is a picture perfect square wave, nothing that would cause any problems.
When I then connect the encoder output to my PFI line (with or without the oscilliscope) I get false triggering due to intermittent (seemingly random...) high frequency noise "blips". Out of 360 expected samples, I will typically get between 2 and 6 "bonus" samples... When captured on a scope, the noise looks like a decaying sine wave and lasts for only a few us. the peak magnitude is tyically around 2 V or so as shown on the scope, which is apparently just enough to make my card grab a sample.
Since the noise is only present when the encoder signal is attached to the DAQ, it seems that the DAQ is somehow inducing noise into the signal.
I have been fighting this problem for a while now and tried the following:
1) I first tried the raw encoder signal, but then added the Schmitt trigger, increased the signal strength of the encoder lines by adding resistors to ground, double checked my shielding, etc...
2) I verified that my ground potential between my card and my conditioning circuit were not causing problems. The conditioning circuit and encoder is now powered of the card itself, which should resolve any possible problem with grounds.
3) Cursed at various inanimate objects (made me feel better but didn't help the situation)
4) Checked if I could set a minimum pulse width required to trigger off of an exernal scan clock (I can't with my hardware.)
5) Swapped my card with a card of a different type (problem is still there)
If anybody out there has some recomendations, I am open to anything.Hello OSU_Mech_Eng,
I'm not quite sure how the DAQ card could be inducing glitches into
your digital signal. Digital signals from mechanical devices like
quadrature encoders can often be glitchy or bouncy, but your schmitt
trigger should act as a debouncing filter to clean up that digital
signal. It sounds like you have thoroughly troubleshooted this
problem, and I would recommend moving on and trying to use a counter on
your DAQ board to generate the digital signal, rathar than using the
raw signal from your encoder/schmitt trigger.
You were correct when you stated that the best way to do this is by
configuring your counter to perform retriggerable pulse
generation. You can use the signal of from your encoder to gate
the internal clock on your DAQ card, creating a clean digital
signal. By setting the minimum pulse width of the signal, you
will be able to ignore the small glitches in your signal. Here is
a link to some Knowledgebases describing how to do this:
How Do I Remove Glitches or Add a Debounce Filter to My Digital Signal?
How Do I Define the Parameters for Pulse Generation in NI-DAQmx?
For further reference, on all of NI's new M-Series DAQ cards (PCI
625x), the PFI circuitry contains built in debouncing filters to
protect against small glitches in digital signals. If you have an
M-Series card lying around, it might be helpful to give that a try.
I hope this helps,
Travis Gorkin
Applications Engineering
National Instruments
www.ni.com/support -
Hi
I ma using 6070E daq. I am generating a infinite pulse train using one of the counters. I want to generate another pulse train which should 90 degress phase shifted with respect to the previsously generated pulse. How to implement this using the counters in the DAQ card.Hi Gopal,
1) yes the frequency generator is programmable. You have 2 timbebases (10MHz and 100kHz) and you can divide down by any integer between 1-16. Those are the only frequencies you can use.
2) The way counters work is that you can apply a gate signal to the counter which will cutoff the output. Therefore, you can have a second counter generating a pulse train of an equivalent frequency to the frequency generator (fout) but you don't want it to start immediately. You want it to start only after a short delay (equivalent to a 90d phase). Therefore, you need to "gate" or prevent the output on this counter for that small delay period of time. The way you can do this is by using a second counter to create a delayed pulse. You would
connect the output of that counter to the gate of your pulse train function. That way, during the delay period of the pulse, you won't be outputing your pulse train yet. When the pulse (high-time) of your pulse reaches the gate, then your pulse train will start generating its pulse train (which is consequently delayed by the amount of delay used in the single delayed pulse counter). Since you don't want your pulse to go back low, you will have to turn off or clear your pulse counter while it is high. That way the signal on the gate will remain high forever.
Your better solution is to use a PCI-660x card to perform this action. You will have more counters which will give you a greater range of frequencies to choose from and you will have more accurate timing of the signals.
Anyway, hope that clears things up. Have a good day.
Ron -
NI PXI 6229 DAQ Card Digital Output High/Low Levels
Hi everyone, I can't seem to find in the NI PXI 6229 DAQ spec what the Digital Output high voltage and low voltage is when I set a digital signal high and low. What is the voltage when I set a Digital Output "HIGH" and what is the voltage when I set a Digital Output "LOW"?
Thanks!See the digital I/O characteristics section of the specs. Typical ttl levels.
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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 -
How do you configure the antialiasing filters on a PXI-6120 DAQ card?
I'm am using Measurement Studio 7.0 and C#. I am trying to use the AIParameter function in the CWDAQTools control.
I was originally trying to use the approach in the link, but am getting a type mismatch error. Here is my code. Maybe you can see what I'm doing wrong.
int device = 4;
CWAIParameterNames paramName = CWAIParameterNames.cwaiFilterSetting;
string channelString = "1";
CWDAQParameterOperations operation = CWDAQParameterOperations.cwdaqParameterSet;
double floatIn = 100000 //100 kHz for 6120;
CWAIParameterValues valueIn = CWAIParameterValues.cwaiVolts;
string stringIn = "";
bool boolIn = false;
object deviceOut = new int();
object valueOut = CWAIParameterValues.cwaiVolts;
object floatOut = new double();
object stringOut = new string(new char[0]);
object boolOut = new bool();
axCWDAQTo
ols1.AIParameter(device, paramName,
channelString, operation,
floatIn, valueIn, stringIn,
boolIn, ref deviceOut,
ref valueOut,ref floatOut,
ref stringOut,ref boolOut); -
Measuring the frequency using PCI 6221 Daq card
Hi
I want to find the frequency of an external signal.
How can i do that give me some idea or example.
Regards,
HariIf you need to capture the waveform look at the aquire waveform examples and add the
Extract Single Tone Information VI
Owning Palette: Waveform Measurements
VIs
Requires: Full Development System
Takes a signal in, finds the single tone with the highest
amplitude or searches a specified frequency range, and returns the single tone
frequency, amplitude, and phase. The input signal can be real or complex and
single-channel or multichannel. Wire data to the time signal in
input to determine the polymorphic instance to use or manually select the
instance.
(copied from the help)
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ' -
Which DAQ card support to Capture AC signal voltage?
I am new in Labview programing and i plan to capture AC Voltagel(Not DC voltage).
I have DAQ 6009 card.
My question is DAQ 6009 support Capture AC voltage? otherwise which DAQ card support to capture AC voltageCPUT wrote:
I am new in Labview programing and i plan to capture AC Voltagel(Not DC voltage).
I have DAQ 6009 card.
My question is DAQ 6009 support Capture AC voltage? otherwise which DAQ card support to capture AC voltage
An AC signal is nothing more than a constantly changing DC voltage. Ok, there's more to it than that. But still, the DAQ takes quick snapshots of what the signal voltage is at a given instant. If you take enough of these snapshots, you can recreate the signal. Niquist states that you need to sample at at least twice the bandwidth of your AC signal. I recommend more of 3-5 times.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines -
Using PXI 7352 Motion card and 6025E DAQ
Dear Sir,
I am using SCXI 1520 along with PXI 1011 & E Series DAQ (6025E) to measure the Load Value of a load cell. I am also using PXI 7352 Motion card to control the velocity of a Plunger. Now my requirement is to stop the movement of the Plunger depending on the value I read from the load cell. I am not able to achieve the stoping accuracy for high speeds (around 150mm/sec) in the software. Can it be possible with the use of Motion Control card and RTSI signals? If so, how can I do that? (I am not used any limit switches as the load value at which the Plunger should stop is user programmable and I am using DAQ card in Multiplexed mode because i am reading more number of analog inputs with only one DAQ card)
Ramkumar. D
Soliton Automation,
India.Hello.
Based on your post I am guessing that you are performing the control in software, i.e. starting a velocity move, and then reading the load cell until it reaches a threshold, then stopping the motion. As such you are essentially limited by the software control loop rates.
You are using PXI so it is possible that you are using real-time. If not, one solution could be to implement a real-time application that would be more deterministic, but again this would still depend on the software.
Depending on your system (stepper or servo), you could implement a direct analog feedback into the motion card itself, but this would require a signal which has a range much greater than your load cells. This is only a good option for servo axes. If this was somehow possible, you can tell the motion controller to move to a specified LOAD instead of a specified position/velocity. Provided you could appropriately condition the signal, this is the best choice.
Unfortunately, you cannot implement limit switches/etc over RTSI, so I believe that this will not be a good option.
A third, and probably most un-desireable option, is to output a voltage on the PXI-6025E proportional to the load received from the load cell. This voltage could then be used as the analog feedback for your motion device. This, however, still adds the software layer of delays.
I hope these ideas help you out.
Regards,
Colin C.
Applications Engineering
Colin Christofferson
Community Web Marketing
Blog -
Configure DAQ cards in RT PXI system
Greetings all,
I'm just trying to learn how to use Real Time and I'm having trouble setting up the DAQ cards in the PXI chassis.
I am able to successfully connect to the PXI RT system and run simple VI's that have no DAQ or VISA access.
What I can't any info on is how to setup and access the DAQ and serial ports on the RT system. A quote from teh help file says,
"To configure remote DAQ devices, select your DAQ device from the Devices and Interfaces category under My System. Select Tools»NI-DAQ Configuration»Remote DAQ Configuration from the MAX menu to launch the Remote DAQ Configuration dialog."
I've tried this and it wants to see the RDA server running on the PXI, which of course isn't there sin
ce it's running RT.
What am I doing wrong here?
I'm running a PXI-8156B with a PXI-6071E and PXI-6713. This also has NT4 installed. Both PXI and host machine have LVRT 6.0.3, NI-DAQ 6.9.1
The host is running Win200.
Thanks
Ed
Ed Dickens - Certified LabVIEW Architect - DISTek Integration, Inc. - NI Certified Alliance Partner
Using the Abort button to stop your VI is like using a tree to stop your car. It works, but there may be consequences.I'm using:
LabVIEW 6.1
NI-DAQ 6.9.2f4
MAX 2.2.0.3010
This may be obvious to others, but it certainly was not to me...
I wanted to configure devices on my remote PXI RT system, and I experienced the exact situation described above.
All the instructions and help I could find seemed to suggest that I should select the following menu item:
Tools >> NI-DAQ Configuration >> Remote DAQ Configuration...
But when I went there and entered the name or IP address of the Remote System, MAX couldn't find it. The PXI system was listed in the "Remote Systems" folder, and I could set up its networking parameters and software downloads from the "Remote Systems" folder.
It turns out the
key is to:
right-click on "Devices and Interfaces" in the "My System" folder
select "Create New..." to bring up a dialog<\li>
selec "RDA/Ethernet Device" then click "Finish" to bring up yet another dialog
specify the remote systems address, then click "Next"
The List of Remote Devices Appears!!! (Hallelujah!)
select a device, "Next", specify a local device number, "Finish"
Now the Remote Device is listed in the "Devices and Interfaces" folder of "My System" (strange that it's not listed under the Remote System - but who cares at this point).
repeat for each device
Now you can go back and select that original menu item (Tools >> NI-DAQ Configuration >> Remote DAQ Configuration...), specify the address, and (Behold!) there are those pesky remote devices.
(NOTE to NI... If this process is described anywhere in documents or help files relating to configuring devices on a remo
te RT PXI system I couldn't find it. Perhaps my trouble is that I've never used a PXI system or remote devices prior to trying to us LabVIEW Real-Time, but I'm probably not the only person in this situation.) -
NI DAQ card not find PXI-4070/PXI-6602
In the course of daily use, I found the acquisition card is often missing, does this problem how to solve?
The Version of your NI-DAQmx Driver?
--> 9.1.5
Whichever Operation System are you using?
--> It wasn't working on Windows XP. I now installed Windows 7 (32 bit) and it is still not working.
Do you try to set the PXI-6122 in another slot of your Chassis? What happend then?
--> The problem is not related to the PXI-6122 card, but rather to PXI cards (and maybe HP computers) in general, as I found out in the meantime:
http://forums.ni.com/t5/Multifunction-DAQ/DAQ-cards-not-selectable-although-listed-in-MAX/td-p/12426...
When I put the card into another slot (there were only two free slots), the PC didn't boot anymore. -
Software Updates for Remote PXI System/DAQ-mx Self Test
1) In MAX, I'm attempting to run the Labview Realtime Software Installation Wizard. When I select the software for install, I get an error "Cannot Process Install because other Dependencies are required: Labview RT 7.1.1". What should I do to correct the problem? I'm trying to update both DAQMx and Traditional DAQ from 7.2 to 7.3. The wizard actually indicates that the remote system only has 7.2, and that it sees that 7.3 is available.
2) Also in MAX in the Remote System Tree, I get an error when trying to perform a self test on my PXI-6025 card, or when I attempt to reset it. The error code is 88705. I noticed on another post that there might be the need to perform a repair of the installation. This was done for both DAQMx and Tranditional DAQ, neither of which fixed the problem.
3) In MAX I have used the Tools>>Traditional NI-DAQ Configuration>>Remote DAQ Configuration to configure my PXI-6025 DAQ channels, accessory, device #, etc. I then proceed to run a Analog Input VI on the remote system by correctly targeting it and selecting i.e. channel 0. No errors occur. However when I try and select "Browse" under the channel control, the "Select Names" window pops up empty. I would assume that this window would pop up with the DAQ channel names assigned during the channel configuration of the PX-6025??? Whats missing here?
Thanks
Pete.Hi Pete,
I'm assuming you are using LabVIEW RT 7.1, since that is a requirement for using DAQmx. Here are my responses for your three issues:
1) You are correct in assuming you can upgrade the DAQ drivers in the manner you outlined, normally that works fine. However, as the following KnowledgeBase points out, the list of dependencies vary for different installs.
http://digital.ni.com/public.nsf/websearch/F5D80FBE806B4B9D86256F0F005630CF?OpenDocument
Do you have LabVIEW RT 7.1.1 installed, which appears to be the required dependency? If not, you may download this from ni.com>>Drivers and Updates
http://digital.ni.com/softlib.nsf/MainPage?ReadForm&node=132010_US
If so, but the problem persists, please post all versions of your software so I can determine where the incompatibility lies.
2) After we take care of upgrading the DAQ drivers, let's see if the 88705 error goes away, it might take care of it.
3) Again, all the steps you described are correct. It might be that all these problems are related and due to a bad install of NI-DAQ.
When a number of software issues like this arise all at once, it might be best to just re-format the controller and perform a fresh install of everything. Often times that will correct the erroneous behavior.
Regards,
Jeff M.
Applications Engineering
National Instruments
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