Performance measurements

Hello. I'm trying to verify the CMRR specifications for the NI PXI5922 Digitizer using the two channels in differential mode, but I don't reach the specification. The signal source is a PXI 5441 AVG. The CMRR is measured by applying the same signals to both channels on the digitizer via a T-coupling and quite short coaxial cables of the same length from the AVG. And then the resulting voltage is measured to estimate the CMRR = 20*LOG(Vcm/Vout), where Vcm is the applied common mode voltage and Vout is the resulting output. The results I get for 1 kHz is about 94 dB and for 100kHz about 75dB. According to the spec the 5992 should have over 90 dB CMRR up to 300kHz. I was using the given examples in Labview to generate the signal and making the measurement. So why doesn't our 5922 meet the spec? Is there a better way to validate the CMRR? Or might it be something wrong with the digitizer? Best RegardsStefan Johansson SP

Thank you for the answer! If the spec that you are linking to is the latest then my measurements are not that far from the "typical" curve showed in figure 1. The spec that I have is more optimistic, showing a flat curve all the way up to 200kHz. The 50 dB that you are talking about is specified when the channels are used in unbalanced differential mode. This means that one signal is applied to the "shield" of the coaxial cable, giving the 5922 two differential channels. I want to verify the CMRR when two channels are used as one "real" differential channel and the CMRR for that is in figure 1. Best RegardsStefan Johansson

Similar Messages

Measurement, visualization and saving data in parallel: Performance question

Hello,
I have written an application with 3 loops running in parallel.
The first loop does only measure and analyze measurement values from a DAQmx device (3 analog input signals from 3 sensors with 1000 Hz).
The second loop does only do the visualization with a graph per sensor continously. The data will be sent from the first loop through a queue.
The third loop only saves the data to a file after a measurement has finished. The data will be sent at the end of a measurement from the first loop, too.
There are 3 measurements running asynchronous.
That means it could be that only one sensor will be read, but it also could be that 3 sensors will be read. The duration of each measurement phase and the beginning/end is asynchronous.
Now I have the following problem:
Measurement 1 starts
A short time later measurement 2 starts
Measurement 2 will end, the measurement values will be saved into a binary file
Measurement 1 is still running but the visualization of measurement 1 stops for about 1 second during the saving process. After the data is saved, the visualization runs normally again (no data is lost because of the queue).
Why does tha graph stop its visualization during the saving process (I have a dual core cpu)?
How can I do this in a way, the user does not see any lags?
It all works fine but the "interrups" look very unprofessional.
Regards
Matthias

Hello,
I'm using the producer/consumer pattern.
Maybe it could be, that the dll calls I'm using for saving will interrupt the whole program: http://lavag.org/files/file/212-sqlite-labview/
When I use the LabVIEW File-I/O vis all is fine. But when I use these database vis my application will lag.
Any ideas why this is so? Could it be that the dll calls freeze the application during the saving process (LabVIEW 2011)?
Here are thze dll settings:
Attachments:
dll_settings.PNG ‏50 KB

Which stage the Prompt will be performanced?

When I set a Prompt with a default value, is the Prompt will be performanced at database side? Or it will be performaced at BIEE Server side after the SQL results have been loaded here?
Due to the tuning of BIEE is a big issue now, and I can't find any useful infomation on it, Could anyone tell me some Document Name or any blod address to learn more tuning BIEE?
Thanks,
Satine

Thank you for your reply.
I have noticed the Prompt is executed at BIEE Server side. If I am right, then I am very curious how to tune the application like this: when the first time open dashboard with no default value (All) as Prompt is very slow, then I choose any values in Prompt, they are all really fast.
Satine

IMC Performance at a Glance

Hi,
Does anyone know if it is possible to edit the default "Performance at a Glance" view such that it displays a trend line for for interface statistics (really only want bit/s in and out) instead of a data grid?
I can't seem to see an obvious (or non-obvious) way from the doco or from within IMC itself.
A trend line would be more helpful for me. It would be nice to be able to create custom PaaG views that could then be applied to multiple devices as a template.
-Felipe Avelar-
Copy By "MartiBarber"

Anna,
    Thanks so much for the reply. That helps a lot.
    I am still wondering about one thing, though. According to the documentation, the "A" prefix in a Modbus DSC address means that it will return an array of data, whereas something like the F prefix is for a single precision float. When I create a channel, I pick the F300001 option, and the address that is returned is a range: F300001 - F365534. The range would imply that a series of values will be returned, e.g. an array. I always just delete the range and enter a single address. Is that the intention? Does it return the range just so you know the range of allowed addresses?
   OK, I'm actually wondering two things. Is there a reason why the DSC addresses start with 1, e.g. F300001, instead of 0, like F300000? For the old Modbus API from LV7, one of the devices we have that uses that API has a register at 0. How would that be handled in DSC?
Thanks,
    Dave
David Thomson Original Code Consulting
www.originalcode.com
National Instruments Alliance Program Member
Certified LabVIEW Architect
There are 10 kinds of people: those who understand binary, and those who don't.

Writing to file limiting system performance

Hello,
I really could use some help with my VI in terms of writing data. I’ve had a LOT of help optimizing my code and am trying to enhance the performance in terms of data acquisition. However, it seems as though writing to a data file is really limiting the frequency I can sample at. I’ve done some research and understand that writing data at every iteration of the while loop and the build array function slows things down. How would I modify the code so that the array buffer would store maybe 5000 data points before writing to a file, then clearing the array? That would keep the array size small, as well as reduce the number of times the program is performing the write to file function. Is there a better way of doing this? I’m open to any other ideas as well.
I am taking data from 14 channels, and would like to sample at 1 kHz each. The task right now is created within Measurement and Automation Explorer, and the number of samples is at 100. I also use a buffer indicator, which will generally grow out of control, no matter how much I modify the number of samples and the frequency. The length of my test can last upwards to 6 hours, so it needs to work that long without crashing.
The code and attached subVI’s is attached. Hopefully it's all there.
Thanks for your help,
Alex
Attachments:
Test Program.zip ‏295 KB

Lynn,
Yea, I'll have to keep on the block diagram size in the future. Can get unwieldy.
I tried incorporating the Recent History Buffer example into my code. I did have a few hang ups, which are giving me some trouble. Mostly, how do I connect my waveform data to the Buffer VI? Will I be able to have all my channels connect to this? Also, ultimately I will have two write to file VI's. Can the buffer differentiate between which file to write?
Thanks,
Alex
Attachments:
Instrument Panel V1.1 (Labview 8.0).vi ‏159 KB

GPIB Ethernet/100 Performance

Does anyone have some real world peformance measurements on the transfer speeds of the NI GPIB-Ethernet/100 box. I am very disappointed in the performance of a block read which is approximately 6ms/byte transfer (tested from 20 bytes to 32kbytes block transfers). This is on a 100 Mb Ethernet. I can ping the box with 64 byte round trip transfers at ~0.7ms/packet.
I almost feel that the GPIB-Ethernet Box is not buffering my GPIB transfers.
Thanks

Actually ignore my question. My transfer speeds are ~6 microseconds/byte (not milliseconds!). This is still a little slower than I would like, but not totally unreasonable! Note the vertical axis in the included plot (pdf) is in ms, so the linear coefficient in the fit equation is 13 microseconds/(16 bit word).
Attachments:
GPIB_ENET_Plot.pdf ‏25 KB

T410s with extremely poor performance and CPU always near 100% usage

Hi,
I've had my T410s for almost a year now and lately its been starting to get extremely slow, which is odd since it used to be so fast.
Just by opening one program, Outlook, or IE or Chrome, just one window, it will start to get extremely slow and on task manger I can clearly see the CPU usage at 100% or very near.
Also another thing I noticed was the performance index on the processor dropped from 6.8 to 3.6!!!
I did a clean Windows 7 Pro 64Bit install, I have all Windows and Lenovo updates installed and the problem persits
What is happening and what should I do??
Thank you
Nuno

thank you again for your answer,
I've done that but hard drive health is also ok as you can see from the screenshot.
IAt the time of the screenshot I had just fineshed to boot up the laptop and it wasnt hot at all.
I am getting desperate here, I am unable to work with my T410s
Link to picture
Thank you
Nuno
Moderator note; picture(s) totalling >50K converted to link(s) Forum Rules

Feb 2009 T500, SSD performance problems

I just bought an Intel X25-M 80GB drive (with the updated 8820 firmware) for read only database data files. I installed an eSata ExpressCard 34 and put the drive in a Rosewill enclosure. All of these items are rated at 3.0 Gb/s SATA speeds. But, when I benchmarked the drive it flatlines at around 130 MB/s. Oddly close to the SATA 1 or UDMA 6, so I looked into the device manager under "SCSI/Raid controllers" and found my SATALink controller. It reads that the "Host Link Speed" is 3.0 Gb/s, but the current transfer mode is "Ultra DMA 6". Is there a reason my new T500 laptop isn't able to run at the full speed of the ExpressCard? I was looking forward to those 250 MB/s reads I've been reading about.

anti00Zero, thank you for your replies. I have figured out what is going on with my situation. It turns out that the SI processor chip on the eSata expressCard has a maximum throughput of 130 MB/s. There is one other option that would provides a throughput of 200MB/s, but it costs $299. It's not likely they will sell many of those cards, when one that provides 130 MB/s costs only $45. In any event, I'll probably end up using the Intel X25 on my desktop because I dont want to have a $400 SSD go to waste at 130 MB/s. Lenovo T500 is working great.

BlackBerry z10 battery poor performance

Hey i have a question with regards to how am I supposed to improve my battery on the z10. I bought this phone last year at full price from my carrier. Since then the battery performance has been very poor... even after the number of updates and reducing which apps are running, it still won't last more than 5 hours when using the phone. in fact I would say it drains very quickly. I see the % sign on the battery and it moves from 100% to 87% very quickly like within an hour when i am using my phone. I have done a lot of research over the past year and read forums on how to improve it and have had no results. Can anyone provide me any advice? Perhaps someone from blackberry themselves? I am really disappointed because I could have spent that money on a different phone which has a battery that actually lasts the day. Thank you and I will await for some feedback.

dgosman wrote:
Have you checked if there are any specific apps that drain the battery ?
Settings->App manager-> Device monitor->Battery
That option is only on newer OS versions.
What OS are you on and do you have many email accounts set up that sync contacts, calendar and more?
I had a corrupt contact that would try to sync over and over again.
Start with this if you sync Over The Air with Outlook
In outlook Make a new folder for contacts called backup
move all contacts to the folder and wait for all to be removed from device
then pull battery on device and put back in
After device boots move contacts from backup to the contacts folder and wait for them all to appear
Make a new contact in outlook and see if it gets to the device.
highlight calendar
goto file import/export
choose export to file
choose Persoanl folder pst, next
make sure calendar is highlighted and choose subfolders if you have them, next
save to desktop with a name you can remember, Finish
Click ok on screen popup
Go to view, arange by events
delete all entries.
close outlook and any word files, open outlook back up after 15 seconds.
Then
goto file import/export
import from another program or file, next
choose Persoanl folder pst, next
find the file and import
Choose highlight calendar and Finish
Change view back to what you want and try again.
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G570 Choppy Sound - Poor Performance

Hi I'm currently having a few issues with my laptop All drivers are up to date
They all seem to happen at the same time so I believe its a internal issue
A lot of the time lately randomly my sound will get really choppy a static sound right when that happens the computer will have terrible performance doing anything ive run system restore to factory setting but that seems to only fix temporary. Also i have alot of trouble restarting the system a lot of the time It gets stuck on starting windows 7...
Not sure if relevant but month after buying it the keyboard went out completely but i was able to fix with restoring to factory settings...
I hope someone can find the problem :/ I will be unable to respond until later tonight will be going to work soon thx for help
Moderator Note; subject edited to reflect the content

Hi Brandon045 and welcome to the community,
Is your problem anything like this thread ?
What antivirus are you running? Any 3rd party firewalls? You might want to open your resource monitor and see what the processor usage is when this happens.
Dave
T430u, x301, x200T, x61T, x61, x32, x41T, x40, U160, ThinkPad Tablet 1838-22R, Z500 touch, Yoga Tab 2 Windows 8.1, Yoga Tablet 3 Pro
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Write Data storage VI performance issue

I have a program that logs data from mulitple channels. It waits for 500 points from each channel, then saves the data (as a raw 2D DBL array) to file, wait for another 500 points, saves and so on. At the end, I have a raw file. I created a utility VI that would take the raw file and converts it to a tdm file so I can read it in Diadem. The utility VI has a for loop. In each iteration, the loop reads one data segment (the 500-point 2D array), converts the channel data to waveforms and then writes/appends to a tdm file using the Write Data (Channel) storage VI. The VI works fine for small files. But as the file gets larger, the conversion time seems to increase exponentially. Eventually grinding to a halt.
I noticed that each iteration of the for loop seems to take longer and longer. So I suspect the Write Data VI may not be simply appending to the existing channel data. But instead, each time it's probably reading back the waveform data already saved, recombine them with the new data and then rewrite the entire file. This is just a guess.
Anyway, I really need some help resolving the performance issue. Any response will be appreciated. The conversion VI is attached.
S.
LabView 8.0
Message Edited by Seaman008 on 06-01-2007 01:50 PM
Attachments:
Convert2.vi ‏184 KB

Here are two profile captures. Each capture start at the first entry into the inner-most for loop and stop when it exited the loop. Profile2.txt was captured when processing a RAW input file twice the size as in Profile.txt. I'm not familiar with the VIs listed, but it shows that lot of time was spent in _saveDdtAttributes.vi and _saveDDT.vi.
Attachments:
profile.txt ‏131 KB
profile2.txt ‏132 KB

Inconsistent Parallel Loop Performance

My original question was can traditional DAQ devices run in parallel loops? I have some extensive data processing and additional automation that would be a lot easier to do in parallel with an acquisition loop rather than cram it all into the acquisition's while loop. As I was building an example VI, I discovered the answer seems to be "sometimes".
I am working on a calibration rig for hot wire anemometers. It requires pressure values to be read into a PCI-4351 (traditional DAQ) for the duration of the calibration and record wire voltages to a PCI-6110 (DAQmx device) only when the pressure values have settled (i.e. the stream velocity is constant). Inevitably, both devices will be polling data simultaneously at some point.
It seems that the 4351 would transfer its data to a parallel loop, but not when 6110 was running and vice versa - and sometimes the buttons to stop the loops wouldn't work. Will traditional DAQ and DAQmx devices not perform parallel tasks simultaneously?
The attached VI might clear up the parallel structures I'm talking about.
Andrew
Andrew
Attachments:
ParallelLoopsExample.vi ‏32 KB

Altenbach,
You pointed me a good direction - I wasn't familiar with action engines until you mentioned them, but after some reading (namely Ben's AE nugget), you have me convinced (although not entirely sure on how to proceed) so here come the questions!
1. I tried to use Ben's running average example as a template - what should the cases inside my AE be? Right now they're "initialize", "acquire", and "close". However, I have to pass a value from initialize to acquire to close - so as is, the VI won't run.
2. Ben had his AE in a loop to add data to the array and in another loop to perform the running average calculation. Since you end up with two of the same thing in your BD, how is this better than creating a local variable?
3. Best practice? I'm pulling values from several channels - should I isolate each channel an put it into its own SR within the AE or keep the data together and have a single SR for the 2D array?
I don't expect anybody to have the 4351 drivers installed - so the what you're probably seeing as three "?" VIs in the "Initialize" panel are the VIs needed to initialize the device (sampling rate, number of scans, etc.), the single "?" in "Acquire" reads the data and the two in "Close" end the acquisition.
Brad,
Thanks for the tip - I'll keep that in mind when I'm implementing the 6110 acquisition into my code
Andrew
Attachments:
InputAE.vi ‏20 KB

IMAQ AVI read frame performance

I've been playing around with the read AVI with buffer example in the Developer Community. It reads all the frames of an AVI into memory and then plays them back at the appropriate frame rate. This works ok with very small AVI files but with anything larger it gets slower and slower until it almost stops loading the AVI. At that point it seems to be loading less than 5 frames per second and is killing my cpu. I have plenty of free RAM during this.
https://decibel.ni.com/content/docs/DOC-8479
This is the case with the play AVI example that comes with Labview too (without a buffer) which just loads and plays one frame at a time. Can someone suggest a way to improve the performance of an AVI player in Labview? My ultimate goal is to read an AVI and detect changes in motion of objects by comparing two frames at a time. These AVIs are going to be at least 5 minutes in duration at a frame rate of 30 fps.
I'm using Labview 2009 with the Vision Developer installed.
Attachments:
image_png.png ‏77 KB

VTKim wrote:
Hi,
One thing we could implement is a compression filter that is on the IMAQ AVI Create VI used in conjunction with the IMAQ AVI Get Filter Names VI. Also, what is the RAM available on your computer and what size images are you acquiring and saving to AVI? Thanks!
Kim
Thanks for replying. I'm running labview 2009 on a dual core pentium 2.3 GHz with 4 Gigs of ram. It typically has 2 Gigs free while running the program.
I'm not tryingt write an AVI, I'm trying to read an AVI. The frames are 352 x 240 in size. I've tried several read AVI examples and they all act the same way. They slow down quickly and the hard drive and CPU are really cranking away.

Poor reflective memory read performance

I'm having some trouble with the GE 5565 PIORC reflective memory set of VIs for use with our reflective memory setup. I need to copy a pretty sizable chunk of memory out of reflective memory and into a DLL I've written, but the performance on the "GE 5565 PIORC:GE5565 Read (Cluster).vi" is not where I need it. I need to copy somewhere in the realm of 12k out of reflective memory at a high frequency, but the call to read those 12k takes longer than the period I need to gather the data at. I apologize in advance for the image-heavy post, but I think it's worth it to show what I've got.
Here's a picture of my setup to benchmark the Read call runtime:
Here's a graph of runtimes of that Read call, in microseconds:
I need it to run in way less than 16 ms, which doesn't seem unreasonable to me for only 12k. I did fool around with the DMA version of the Read (which I don't really understand, and the documentation is nonexistent as far as I can tell). Here's my test setup:
And here's a chart similar to the one above:
Way better, though I have no idea if it even does what I think it should So, I have a few questions. First, is there any way to get better performance out of that Read VI? Some other library I should be using, some setting I should be setting, some other way I should be benchmarking its performance, maybe even some way of doing this with another DLL? Second, if the Read can't achieve the performance I need, what's up with the DMA version, and how would I use it properly? Is the performance advantage that it appears to be giving real, or just an artifact of some mistaken way in which I'm using it? Thanks!

Hi dgoes
Windows is not a deterministic operating system so the loop cycle time that you are getting might be the best time that the windows system can achieve. In order to benchmark your code you can also use the input node and the output node of the timed loop. Check the following link.
Timed Loop
But it will be nice to know if you are working on a real time operating system or windows? Because unfortunately the windows operating system is not a deterministic system so the time loop might not work as expected. Here are a couple of links with information about this.
windows 1KHz time loop limitation reason
What is a Real-Time Operating System (RTOS)?
Which driver are you using for the GE 5565 PIORC? Is it this one?
GE 5565 PIORC
If it is, please notice that this driver is neither supported nor certified by National Instruments. This card is supported with NI VeriStand. Please check the information on the following links.
Getting Started With the GE cPCI-5565PIORC Reflective Memory Module
GE cPCI-5565PIORC
I hope that this information answer your questions.
Regards
Esteban R.

Lenovo Z710 - Major Performance Problems - Expert Advice Needed

Three months ago I bought Lenovo Z710 laptop.
Here are some system properties:
Intel Core i7 4700MQ CPU @ 2.40 GHz,
8GB RAM
Hybrid 1TB + SSHD(8G),
NVIDIA GeForce GT 740M / 2 GB,
DVD-R,
Win 8.1
After using the device for 3 months I can't describe with words how dissapointed I am.
It is unbelievably slow. The device with this configuration should do very easily hard things.
However, I have troubles doning even simple things.
For example, currently I am only browsing web and listening music from youtube.
Opening a new web page in Chrome takes 30-40 seconds. Opening a new tab takes aprox. 10 seconds.
Selecting a text and copying it, takes 15 seconds. It is even very frustrating to type even a web address because of the obvious delay in typing. Furthermore, when I listen to music there is also a delay - that makes even listening to music unbelievably frustrating. Just to mention one more time - I only have chrome running!
I have 2 Partitions - C disk (442 GB) and disk D (488 GB).
On disk C I installed Win 8.1. and at the moment on disk C 391 GB are free.
I use disk D is mostly intended for storing images, movies, and music. On this disk 258 GB are free.
Regarding the programs I installed on top of Windows, here is the list: micro Torrent, Adobe Photoshop, Android SDK Tools, Android studio, Avast Internet Security, Brackets, Corona SDK, Dropbox, Foxit Cloud, Foxit Reader, Chrome, Greenshot, MS Office, Mozilla, Skype, Notepad, VLC Player, WinRAR, XAMPP.
When I open Task Manager I see that used CPU resources are aprox. 10%, Memory aprox 35%, Disk 2%, Network 5%.
I am the only user of the device.
In Task manager I read that only Chrome takes the most of the resources taking 130 MB memory.
So why is the device with 4 physical i7 Intel processory and 8 GB SSD so slow, that I can't even type without disturbance with delays?
I don't understand how the device with mentioned hardware can be so slow.
And regarding the software, I don't understand whtat could slow the device - I mentiond what programs were installed and to what extent are resorurces being used.
Please give me your advice on what else can I check and what shoudl I do.

Can you run a system health check once and see if anything is flagged? To do so,
1. Press the + R keys to open the Run dialog, type perfmon, and click/tap on OK.
2. If prompted by UAC, click/tap on Yes.
3. In the left pane of Performance Monitor, click/tap on Data Collector Sets to expand it, click/tap on System to expand it, right click on System Diagnostics, and click on Start. (see screenshot below)
4. It will collect data for 60 seconds before the system diagnostics report will be ready to view instep 3 of OPTION TWO below.
More information here
http://www.eightforums.com/tutorials/52013-system-health-report-generate-view-windows-8-1-a.html
Cheers and regards,
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