NI-DAQ 7 Speed

NI says in the latest newsletter NIDAQ 7 is up to 20 times faster than
older version at least for single point acquisitions.
Two questions:
What's about the speed of reading waveforms?
Is this true with older versions of Labview (6.1) too?
Thanks
Urs

I am sure NI can chime in on this but yes NI DAQmx is about 20 time faster than Traditional NI DAQ. Ni DAQmx is only available in LV7 right now. LV6.1 uses the traditional NI DAQ. In LV7 you can use both versions. The big improvement is the use of multithreading or the concept of skip if busy when reading. This will allow you to read a waveform 20 time faster because the if you are aquiring 1000 points but only 20 are available the traditional analog input will stop and wait for information even if it is not there, the new daqmx will release and then come back to read again rather then waiting hence "skip if busy". Hope this helps.
BJD1613
Lead Test Tools Development Engineer
Philips Respironics
Certified LV Architect / Instructor

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URGENT!!! motor speed control

Dear all,
first let me tell you my system detail:
1. Hacker A100-8 brushless DC motor
2. Master spin 170 pro opto (speed controller)
3. power supply
4. NI DAQ USB-6353
I have already run this motor by using transmitter and remot control, like RC planes fly. Now I would ilke to run this motor from computer. let me give you my setup:
PC > DAQ > speed controller > motor
^
power supply
now I would like to use either matlab/simulink or labview, to control or run my motor in real time using generating PWM signal. can anybody help me out? Thanks in advance.

Since you are wanting to use DAQmx and not any of the Motion software that is made for LabVIEW the examples will be very limited. I suggest playing around with the PWM and Digital Out functions to get an understanding of how they operate.
http://www.ni.com/tutorial/2991/en/
You can also take a look at this example below which uses DAQmx to control a stepper motor. This is a little different than what your DC motor control setup will look like but it should be good for reference if you understand how stepper motors work.
https://decibel.ni.com/content/docs/DOC-6385
I still suggest posting this in the general section of the forums as it will get many more views and thats really what your application is about. This forum will get more views for things like SoftMotion which is NIs motion control software. Since you are working with DAQmx however you would want people who work more frequently with DAQmx to view your post, which will be in the general section of the forum.

XP/LabVIEW 4.0.1 Compatibility

Hi, I am currently doing research at the local University using LabVIEW 4.0.1, PC 1200 DAQ board, and a Pentium 2 computer running WinNT. I am thinking about upgrading my computer in order to handle greater DAQ speeds. My question is concerning the compatibility issue between Windows Xp and LabVIEW 4.0.1. Has anyone tried LabVIEW 4.0.1 with XP; any success? or do I have to upgrade to a newer version of LabVIEW.
Thank you for your help,
Regards,
RTsen

Windows XP was first supported with LabVIEW 6.1. Now, it's always possible that it could work with 4.0.1, but it's very likely that you'll run into some problems. I would suggest upgrading to LabVIEW 6.1. Not only are you likely to experience less problems with the new OS, but you will always gain a lot of new tools in the upgrade from 4.0.1 to 6.1.
J.R. Allen

Using LabVIEW and an E-Series DAQ Card to perform relatively high speed single point acquisition in response to a changing DIO pattern.

I am using the DIO lines on my E-series card to drive an external multiplexer which switches 1 of 8 sets of 3 signals to channels 0,1 and 2 on my DAQ. I need to acquire the 3 single points of data, do a little processing, then update the mux code before acquiring the next 3 points of data and so on. I have been trying to do this using hardware controlled loops but can only achieve a real sampling rate (time between the same set of three signals) of about 200s/s. I am trying to achieve in excess of 800 s/s. Any ideas?.

HI CP,
You are doing pretty good if you are getting 200S/s.
I believe the only way you can get 800 S/s reliably is to go to LV-Real Time. Not for the speed, but for the determinism.
That's my idea.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Pushing the limits of continuous high-speed DAQ + processing, with PXI-6115 + PXI-8360

Hi all,
I'm trying to do continuous high-speed data acquisition + processing. I currently have:
Chassis: PXI-1042Q
AI card: PXI-6115 (x2)
Link: PXI-8360
PC CPU: Intel Xeon W3503 (dual-core, 2.40 GHz)
RAM: 4 GB
The idea is to continuously grab 8 channels' worth of analog inputs, scan for "events", and if found, log the events to disk.
My client would like to use the maximum sample rate of 10 MHz, but I found that above 5 MHz, DAQmx Read.vi can no longer keep up (e.g. at 6 MHz, it takes 110 ms to read 100 ms' worth of data).
Im thinking of getting beefier components, but I'm not sure where the bottleneck is. Here are some thoughts:
1) The MXI Express link
The PXI-8360 is rated for a sustained throughput of 100 MB/s.
I'm not sure how big the data is. PXI-6115's ADC is 12-bit. Does that mean each datum transferred through the MXI cable is 1.5 bytes? Is the data padded? Or is it 8 bytes per datum, because Dbls are being transferred?
2) The CPU
In Resource Monitor, I notice that the CPU usage is 0% at 60 kHz, 8% at 61 kHz, and 50% at 70 kHz (meaning that one core is maxed out). I'm surprised that it keeps up all the way until 5 MHz though.
What causes this high CPU usage? Is it due to the conversion of the data into 1D array of waveforms?
3) Something else?
Have I missed something completely? Is what I'm describing even possible?
Thanks in advance for any advice!

Hello,
Each sample will take up 2 bytes, 12 bits data + 4 empty bits. so the PXI-PCI 8360 is only able to transfer a maximum of 50S/s in this case.
Also, because the PXI bus is shared among all of the cards, two PXI 6115 cards will be trying to transfer 80MS/s or 160MB/s.
Finally, since the PXI 6115 are DAQ family cards, their specifications aren't really written for continuous data acquisition at the upper end of their sample rate, but I'm interested to know if you can get up to 10MS/s with only one card operating at a time?
-Jim B
Applications Engineer, National Instruments
CLD, CTD

DAQ Assist Continuos High Speed Display

I am using the DAQ Assist to read in voltage data and display it as a scrolling chart. When I set it to take "N Samples" it works well, but wont display that data until the N samples have been collected. When I switch it to a continuos mode and set it to take 1 sample buffer at the same rate (20kHz) it actually samples much slower. Any suggestions about how to get a continuous chart that still shows the the data at full speed?
Thanks

The DAQ assistant, while it is great for getting a quick and dirty DAQ task up and running, isn't really designed for high speed data acquisition with precise control. You will likely need to use the lower level DAQmx functions. Start a task, acquire chunks of data in a loop, end the task. You may need to pass the data off to a parallel loop for data processing, display, or logging using a producer/consumer design architecture. Take a look at the DAQmx examples in the example finder.
If you right click on your DAQ assistant and select Open Front Panel, it will turn the Express VI into a subVI that you can open and see how the underlying DAQmx code works.
It may even be a matter of selecting continuous samples in your DAQ assistant, a small number of samples to read, have it in a loop that iterates enough times until you have collected your larger number of samples.

DAQ for rotational speed and flow rate measurements

Hello Everyone,
I'm in a new project and want measure the rotational speed of a diesel engine and the diesel flowrate . I want use NI products, but couldn't decide which DAQ card is the most suitable for me.
I want measure the instantaneous speed from a speed sensor which sends a pulses for each revolution. The speed I want measure is less than 3000rpm. The flowrate sensor will give me pulses as well. Also, I need it to have some AIO channels to measure the voltage and current signals. I would be very apprciative if you can provide me with some suggestions about the most suitable DAQ for me.
Thanks
Mike

Hi Mike,
This is pretty easily done in LabVIEW with a
buffered period measurement. My recommendation would be to start with
one of our example programs. A good example to use is called Meas Dig
Periods-Buffered-Continuous-High Freq 2 Ctr.vi. This example can be
found by going to Help » Find Examples in LabVIEW and navigating to
Hardware Input and Output » DAQmx » Counter Measurements » Period or
Pulse Width. There are a few changes that need to be made to change
this example to a low frequency period measurement using 1 counter.
1. Adjust the blue enum going into the DAQmx Create Channel.vi to "Low Frequency with 1 Counter".
2. Delete the "Measurement Time" control on the front panel and delete the broken wire on the block diagram after doing so.
3.
Adjust the Samples to Read control to something like 10-100. You can
also adjust this to -1 if you want to just read all available samples.
It
is important to note that these samples will just be the period of the
gate signal and won't contain timestamp information about when they
were taken. However, you can use the order at which you receive the
data to tell you information about when measurements were taken.
Another thing you can do is take a software timestamp prior to starting
the acquisition. This would give you a relative means to determine
when measurements were taken or what the speed was at a specific time.
I hope this helps,
Paul C.

Daq with PocketPC any speed limit ??

Hi ! HELP NEEDED !!!
i need to sample 12 chanels with 16ksamples/s ....
so its something like ... 200,000 ksamles/s ...
and make some Min/Max calculations ...
i want to use it with the PocketPC and the Daq 6024E .. and ofcourse LabView 7 ...
the speet limit of daq .. is 200,000 ks/s .. so its ok ..
but what PocketPC speed i need ??? (200Mhz, 300Mhz, 400Mhz) ... and if its actually possible to sample this speed on the PocketPC aplication ....
anybody tried ???
any body worked near the limits ???
what amount of memory needed ??? 64 mb enought ??
anybody ?? plz ??? :-)
its too pity to buy and to find that its not working ...
u can answere also to [email protected]

200KS/s on the 6024E should work fine on 200Mhz StrongARM and 400Mhz XScale CPUs. 200/300Mhz XScales will probably not be fast enough. You will need to download the 7.0f1 patch for LabVIEW and the PDA module to get this level of performance (and to support multichannel).
Due to various factors from both Windows CE and LabVIEW PDA, using the high-level multichannel acquisition VIs in a default PDA install you should expect to be able to acquire somewhere around 10s of contiguous data at 200KS/s. This can be improved to 50s by various means including a lower-level usage of the DAQ driver code. If you require continuous acquisition, this is achievable but more difficult to program, and may not be able to operate stably at 200KS/s.
If you need more information a
bout said lower-level programming please msg me privately.

Data Writing Speed for Excel Sheet while taking data from PCI DAQ card

Dear All,
I am taking the data form the card EX-92026 pci card and writing those datas into the Excel sheet, now i want the data at the speed of max of 10 miliseconds but while writing the data into excel sheet, it shows the diff of 15 ms betn 2 readings, and the card specs says it takes the time of 500 microsecs to give the data, so is there any effect of timing, while writing data into excel sheet? is labview take more time, i am using the Open file, write file and close file method and write to spreadsheet file method, but none of them is giving me the effective timing that i wamt, so can u tell me how can i reduce it??????
Thanks,
Nishant

Hi Nishant:
I think I don't understand you very well. If you are using OpenFile, CloseFile and WriteToSpreadsheet VIs, you are not dealing with excel files, but text files.
Writing to file is costly in time. You can:
Open the file just once and
during de process use just file writing VIs as 'write to spreadsheet'... or a more simple one 'write file'
Close the file once at the end.
If you need the process to be faster, you can save all the data at 10ms rate in an array and write to file at the end.
Or write to file every second what you got the last second.
Hope it helps
Aitortxo.
Aitortxo.

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 KB

Sunny;
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

What is maximum read out speed of USB DAQ 6343

hello everyone,
we have new USB DAQ 6343.Its application note(or say characteristcs) says that it's sampling rate is 500K Sample/second.Now i need some clarification from you guys.I have to read digital data(serial or parallel). so plz tell me how much far I can go with this product for both ways.
thanks in advance,
Solved!
Go to Solution.

Unfortunatly I can't get the spec online
Error
You are not authorized to view this document
but you should have get it with your device
However the datasheet is telling me something like 500kS/s aggregate (500kS/s / <number of channels read> ), but up to 1MS/s for digital input. However you need to get the data into your PC. If you read one 8 bit port @1MS/s the USB should be able to handle the datastream.
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'

Hi speed non-regen AO with LV DAQ Occurrences

Hi
I need to output 6 non-repeating patterns to 3 PCI-6111's @ 150kHz.
Can anyone explain to me why the attached LV7 Development Library example, with modified defaults and utilizing DAQ occurrences, will not work when more than one copy is run? When I try to run a second copy (with the device number different) the first copy produces a -10803 error.
Another example (also attached) will successfully allow 3 copies to run simultaneously. While it can get the job done, I was wanting to use the DAQ occurences, because I thought that would allow the minimum amount of CPU usage. This is the first time I've had to do anything more with AO than state levels. Am I missing something basic here?
Thanx.
Attachments:
Generate_Continuous_Sinewave_Occurences_dev1.vi ‏117 KB
Generate_Continuous_Output1.vi ‏451 KB

Hi,
I believe what is happening is that your first VI is using DAQ occurrences and locking the driver. This is because traditional NI-DAQ (before DAQmx) is single threaded meaning it can only execute one DAQ process at once. When you try to start another VI with occurrences it times out (error -10803) because it cannot access the part of the driver that does occurrences.
Since DAQmx is multi-threaded it is able to run multiple VI's and can actually trigger on multiple boards. DAQmx will support the PCI-6111 in NI-DAQ version 7.2. Until this is released I would suggest using continuous generation without occurrences when using multiple boards.

Speed up daq counter

Hi,
I'm trying to determine the pulse width of a signal by using the counter of a NI USB 6216. This works reasonably well, except the acquisition is too slow for my needs.
Below you can see a stripped down version of my acquisition vi. In the version depicted stage 2 of the loop takes 3ms to execute. This is the time expected to count the appropriate number of low times (20) in the signal I'm measuring. The whole loop takes 30ms however (measured beginning to end of loop - not beginning to beginning of next iteration).
If I remove start task and stop task vis the loop time doesn't change, the whole time apparently taken up by the read vi.
I'd like the loop to run with less overhead (ideally none :-). Can anyone with more experience shed some light on how to speed up this vi?
Regards Florian
Solved!
Go to Solution.

Partially puzzled by two things that seem in conflict:
1. you're doing a finite triggered task that intentionally misses some pulses while it stops and restarts
2. you're expressing some concern about those missing pulses
One idea to make the stop and restart faster is to use DAQmx Control Task to "commit" the task before starting.
When you do that, cycles of stop and restart can occur much faster than they would otherwise. An example and
some benchmark results can be found here.
Another idea is to perform continuous acquisition of the pulse measurements so you won't miss any. Depending
on your app, that may leave you with the job of timestamping the trigger signals with another counter, and
working a scheme to correlate particular pulse measurement subsets with particular trigger events. Not a trivial
job, but a do-able one.
-Kevin P
P.S. Just re-checked and noticed you're using a USB board. I suspect that's a significant part of the problem.
There's more latency & overhead with USB acquisition, and the effect is stronger when you request small packets
at a high rate than if you requested large packets at a lower rate.
P.P.S. Looks like you alread got an answer before I hit send -- I was just typing a minute here, a minute there
while do some other testing.

Speed measure with DAQ and torque transducer

Can anyone tell me how to convert the voltage i get from torque transducer, which can measure torque and velocity eather. I made a program with labview, but it gives me some voltage. I'd like program converts me that voltage to a velocity.
Thanks for answers.

First of all, we need to deeply understand the signals we receive from the sensor.In my opinion, the information from the datasheet is not the most comprehensive
Sensor requires 12V DC, 160mA excitation.
Torque: 0V-10V, -10V-0V depending on direction - should be connected to AI
Speed 60 pulses/rev - should be connected to counter 0
Angle 360 pulses/rev (two signals- angular encoder) - should be connected to counter 1
What I would recommend is you started with LV examples for:
Hardware Input and Output -> DAQmx
Torque - Analog measurements and then scale the signal to result in strains
Speed - Counter Measurements -> Digital Frequency
Angle - Counter Measurements -> Position
Please find the proper example, scale them properly, make each work individually and in the end, integrate the three examples into one single application,
Mircea

Speed measure with DAQ, how to override the noise

Hello.
I try to measure spped using the counter input. My VI didn't work, so I look at the singnal I get from the encoder and I saw, I get a lot of noise in my signal. That's why program shows wrong values. I connect my signal between PFI8 and DGND on my DAQ 6212. My encoder (torque transducer) gives me 60 pulz/revolution. Is it possible to nullifythe noise with program, or there is a problem with ground. I tried many different ground options, but didn't work
Hope you have any idea.
Thanks a lot.
Simon

Hello Mateusz. Thank you for responding me.
You can see my signal taken from scope and check my vi file. Noise causes regulator of the motor I drive. If regulator is switched off there is no noise and if I turn my motor by hand, I get correct values of velocity, but when I turn on the controller, I get full of noise in my signal, so DAQ card reads all those noise as many signals, so it displys velocity much greater than it's real. I moved my daq card away from controller as much as possible and used coaxial cable, but noise still appear. I hope you have any idea.
I hope you don't mind, because notes in my vi are written in my language. I just wrote them, that I can see what I was doing.
Regards. Simon
Attachments:
DAQmx velocity.vi ‏45 KB
scope_0.JPG ‏118 KB

NI-DAQ 7 Speed

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