Measure speed

Hello,
I want to measure the speed through an encoder.
So My system is composed by
- a PXI 1000B with 2 6025E
- on the first 6025 E, I connect a BNC 2090
So I used the BNC 2090 to connect the encoder with the user BNC and PFI7.
In my application, I synchronize the signal of the BNC2090 and the signal of SCXI1112 connecting to the second 6025E.
But in my application, I don t know how to have the same scan rate for the speed. For the moment I use the Measure frequency.vi but I have the speed only every 0.2s and I need every 0.01s.
So I can I proceed.
Thanks

Hi mous,
Try taking a look at the example: "Measure Buffered Period (DAQ-STC).vi" in
the examples bundled with LabVIEW.
Knowing the gating time and number of encoder pulses per unit, its easy to
calculate the speed in units per second.
Happy Wireworks
Hans Christian
"mous" skrev i en meddelelse
news:[email protected]..
> Hello,
>
> I want to measure the speed through an encoder.
> So My system is composed by
> - a PXI 1000B with 2 6025E
> - on the first 6025 E, I connect a BNC 2090
> So I used the BNC 2090 to connect the encoder with the user BNC and
> PFI7.
> In my application, I synchronize the signal of the BNC2090 and the
> signal of SCXI1112 connecting to the second 6025E.
> But in my application, I do
n t know how to have the same scan rate for
> the speed. For the moment I use the Measure frequency.vi but I have
> the speed only every 0.2s and I need every 0.01s.
> So I can I proceed.
>
> Thanks

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How to increase measuring speed of Agilent 34401A

The process of my program (written in Labview) is:
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I don't have the manuals with me, but I do have a couple of these in my lab. There is an internal buffer where you can store (I think) 512 readings. You can use a digital output to trigger the DMM, and only transfer after every 512 readings (4 times) or perhaps one read per group as you mentioned. I suggest one read per trigger (you can do many more) since it is easier to synchronize with your channel changes. I believe the commands are INIT and FETCH?, check your manual. The two times I know the instrument "clicks" are changing functions and certain range changes. I suspect in your attempts to speed things up you are sending some config. commands each time. Configure it once initially and make certain you are only sending measurement related commands during the scan, any config. changes (even if you resend the current value) will likely cost you time.

What sensor should be used to measure speed of motor

Hi,
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Ayaz,
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Attachments:
CVWAIT33.VI ‏85 KB

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Measuring speed with incremental single counter

Hi,
I need to measure the rotational speed and acceleration of a wheel that has 3 hall sensors on it. I will use only 1 of them en it gives 24 pulses 0-5V for a 360° rotation. How can I measure the speed with only a pulse train. I dont have the Quadric encoder...
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Hey Nitch,
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As you get error when speeding up, it looks like the pulses coming from the hall sensors are to short to get measured by the counter.
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Looking at your program.
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Have a look at the Examples which come with LabVIEW --> Exampled Finder --> Hardware Input/Output --> DAQmx --> Synchronization --> Multi-Function.
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Then you have the choice to log to file during acquisition or after the acquisition.
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Again, also bring your "spanning, stroom and gashendel" inputs to the left loop.
In your right loop you also have a loop counter.
You can simply use the loop iteraction counter (the square box in the left bottom corner with the i). This is also counting from 0 and incrementing by 1 each loop iteration.
Again, you can do this in the left loop and forget the second loop completely.
Hopes this will bring you a step further.
Don't hesitate to post the VI itself. This is always easier to look at than an image.
This way we can also make some modications and post it back.
Best regards,
Joeri
National Instruments
Applications Engineering
http://www.ni.com/ask
Make our forums great:
If you like the answer, don't forget to "Kudos!".
"Accept the Solution" if your question is answered!

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And I thought this would be a tough one....
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What you are trying to do is to isolate the frequency that occurs when a fan blade passes in front of the microphone, compressing the air, pushing the cel of the mic in, then the blade passes, decompressing the air (in relative space of course), pulling the cel out. This is a very strong component of the sound you will measure with the mi
crophone, and should be very easy to see in the FFT. If you want to get fancy, you can isolate this peak in the FFT, apply the math to convert it to RPM, and output the fan speed.
Good luck. 'Sounds' like fun...

Measuring speed, both Broadband and LAN

Hi,
Can someone please advise me of a reliable method of measuring the speed i'm getting on my broadband.
I've tried speedtest.net and thinkbroadband
Speedtest.net showed 94Mb/s with one PC connected to the gigabit port on the homehub when the BT man was here. Now the best I get is about 50, but normally about 25 with the same setup, and other computers on the network drop as low as 12.
For the LAN PCs, are there any recommended tools I can use to try and figure out what's causing the slowdown?
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Hi,
Thanks for the replies,
Yes, i'm on the FTTP trial.
Here's my test results from the PC connected directly to the router at 100Mb/s earlier today.
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Download Speed
57590 Kbps
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106417 Kbps
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IP Profile for your line is -106417 Kbps
2. Upstream Test: -provides background information.
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14759 Kbps
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15000 Kbps
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Upstream Rate IP profile on your line is - 15000 Kbps
And here's one from just now. I guess we're in to peak time now.
FAQ
Test1 comprises of two tests
1. Best Effort Test: -provides background information.
Download Speed
55688 Kbps
0 Kbps
106417 Kbps
Max Achievable Speed
> Download speedachieved during the test was - 55688 Kbps
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15000 Kbps
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Digital frequency measurement speed in labview

I am using a USB 6210 device to measure low frequencies of 50 to 1000 Hz. I need to log the frequency every 50ms. I do this in a while loop in labview using a 1 counter low frequency measurement in labview and saving the data using express VI.Each iteration of the loop takes atleast 60 to 100 ms just to read the frequency inside the loop. How do i increase the speed of measurement in Labview ?
Solved!
Go to Solution.

PraveenB,
Here is a table of the Counter terminals and related PFI lines. This can be found in the NI DAQmx Help. (http://digital.ni.com/public.nsf/allkb/CCDFC93878BD8781862570FC00559980?OpenDocument)
Default NI-DAQmx Counter Terminals
Counter/Timer Signal
Default Pin Number
Signal Name
CTR 0 SRC
1
PFI 0
CTR 0 GATE
2
PFI 1
CTR 0 AUX
1
PFI 0
CTR 0 OUT
6
PFI 4
CTR 0 A
1
PFI 0
CTR 0 Z
3
PFI 2
CTR 0 B
2
PFI 1
CTR 1 SRC
4
PFI 3
CTR 1 GATE
3
PFI 2
CTR 1 AUX
4
PFI 3
CTR 1 OUT
7
PFI 5
CTR 1 A
4
PFI 3
CTR 1 Z
2
PFI 1
CTR 1 B
3
PFI 2
FREQ OUT
8
PFI 6
When you choose counter 1 in the Create channel VI it automatically reserves the gate which is PFI2. If you use Counter 0 then PFI 2 will work fine. Likewise if you use Counter 1 you can use anything but PFI 2.
Message Edited by Jason_D on 10-24-2008 11:43 AM
Sincerely,
Jason Daming
Applications Engineer
National Instruments
http://www.ni.com/support

Measure frequency of Z pulse of an accu coder shaft encoder to measure speed using an 6034 E card

Hi,
I would like to measure the speed of a engine which has an accu coder encoder hooked onto it. It provides 3 pulses A, B, and Z. I am using a 6034 E PXI card. I wanted to know if there are any examples/ideas that could help me with this (I am new to the digital programming in Labview). I have moved to NI Daqmx 9.8 recently from the older version which supported legacy codes and hence in process of updating the code. I also want to know if an external clock source is required to do this. this.
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Hello,
There are several examples in the NI Example finder (you can get here by going to Help >> Find Examples in a LabVIEW window). You can browse to the encoder examples by going to Hardware Input and Output >> DAQmx >> Counter Input. You should be able to find a few examples that will be helpful.
Also, this link is a good resources for getting started using DAQmx: http://www.ni.com/white-paper/5438/en
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Agilent E4980A Measurement Speed and Data Acquisition Speed

I am using E4980A LCR meter, I need very fast data aquisition unfortunately limited by device own speed with 5.6 ms per measurement which means nearly 178 Hz. I am using usb interface with the software provided by NI, in that program I made some modification taking the reading side of the programme in a while loop .
To test my speed I start the program count 5s and stop saving the results to an excell file. If I plot the results in a graph while programme is working I have 60 Hz speed. If I don't, then it is 80 Hz which are far below the potential maximum speed of 178 Hz. If my lap top battery is very low then my speed is worse. But with no battery problem, my celeron laptop performance is the same as an i7 laptop.
Here it is my programme, it is the same provided NI but some modification. What can I do to have higher data acquisiton speed ?
Probably, USB's speed is not enough but I can not believe that while it can save gigabytes of data in a few min can't take 200 datapoint in 1s. Why can't I have 178 Hz speed now and how can I reach this limit ?
Regards.
Attachments:
Read Measurement.PNG ‏44 KB
Read Measurement.PNG ‏44 KB

Instrument communications via serial, USB, Ethernet, GPIB, etc just tend to be slow. The instrument has to interpret the data, react to it, and then send data back. That takes time. A few ms per measurement is quite normal. One option you might have is you could tell the instrument to take several measurements and then request all of the measurements once it is done. I haven't looked into the E4980A yet to see if it can do that.
What exactly are you trying to measure. There might be better ways to get "fast" readings.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions

Measure speed of wireless?

My wireless performance using Time Capsule seems sluggish. How can I measure?

Thanks for the info. You can use a utility like www.speedtest.net on her computer to test the Internet connection speed and compare that with the plan that your service provider is furnishing to you.
What download speed do you see here?
Do other sites download slowly as well, or it just this one?
How many walls and/or ceilings are in the signal path between the main wireless router and her computer?
Have you picked up any new cordless phones recently, or moved them around?
It is normal for the wireless speed to be less than a direct wired connection due to some loss in the wired to wireless conversion process and wireless security settings. The connection speed will also fall off with distance and obstructions in the signal path, as well as wireless interference from cordless phones, other wireless networks at the neighbors, and wireless camera/security systems.

Kernel patch for more CPU families offers measurable speed increases

I wanted to show folks a pretty nice patch that allows one more options when compiling a kernel for CPU families. Complete list included at the bottom of this post. I tested it using three different x86_64 machines running a generic x86-64 kernel and an otherwise identical kernel running with the optimized gcc options.
Conclusion: There are small but real speed increases using a make endpoint to building with this patch.
Details:
1) Three test machines: Intel Xeon X3360, Intel i7-2620M, Intel Core i7-3660K.
2) All ran the make benchmark (linked below) 35 times while booted into a 'generic' kernel. Then all ran the same make benchmark 35 times after booting into an optimized kernel. Below are the optimizations chosen for each machine.
2a) X3360 = core2
2b) i7-2620M = corei7-avx
2c) i7-3660K = core-avx-i
3) Analyzed resulting distributions for statistical significance via ANOVA plots that clearly show statistically significant albeit small differences.
Discussion
1) All the assumptions for ANOVA are met:
*Data are normally distributed as show in the normal quantile plots.
*The population variances are fairly equal (Levene and Barlett tests).
2) The ANOVA plots clearly show significance.
*Pair-wise analysis by Tukey-Kramer shows significance at the 0.05 level for all CPUs compared.
Below are the differences in median values:
core2 +87.5 ms
corei7-avx +79.7 ms
core-avx-i +257.2 ms
References:
Kernel patch: https://github.com/graysky2/kernel_gcc_patch
Bash script that controls the benchmark: https://github.com/graysky2/bin/blob/master/bench
Log file generated by script: http://repo-ck.com/bench/compile_time_o … ion.txt.gz
Links to ANOVA plots:
Complete list of x86_64 CPU Families:
1. AMD Opteron/Athlon64/Hammer/K8 (MK8)
2. AMD 61xx/7x50/PhenomX3/X4/II/K10 (MAMDFAM10) (NEW)
3. AMD Barcelona (MBARCELONA) (NEW)
4. AMD Bobcat (MBOBCAT) (NEW)
5. AMD Bulldozer (MBULLDOZER) (NEW)
6. AMD Piledriver (MPILEDRIVER) (NEW)
7. Intel P4 / older Netburst based Xeon (MPSC)
8. Intel Core 2 (MCORE2)
9. Intel Core i7 (MCOREI7) (NEW)
11. Intel Core 2nd Gen AVX (MCOREI7AVX) (NEW)
12. Intel Core 3rd Gen AVX (MCOREAVXI) (NEW)
13. Intel Core AVX-2 (MCOREAVX2) (NEW)
14. Intel Atom (MATOM)
15. Generic-x86-64 (GENERIC_CPU)
Complete list of i686 CPU Families:
1. 386 (M386)
2. 486 (M486)
3. 586/K5/5x86/6x86/6x86MX (M586)
4. Pentium-Classic (M586TSC)
5. Pentium-MMX (M586MMX)
6. Pentium-Pro (M686)
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9. Pentium M (MPENTIUMM)
10. Pentium-4/Celeron(P4-based)/Pentium-4 M/older Xeon (MPENTIUM4)
11. AMD K6/K6-II/K6-III (MK6)
12. AMD Athlon/Duron/K7 (MK7)
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14. AMD 61xx/7x50/PhenomX3/X4/II/K10 (MAMDFAM10) (NEW)
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16. AMD Bobcat (MBOBCAT) (NEW)
17. AMD Bulldozer (MBULLDOZER) (NEW)
18. AMD Piledriver (MPILEDRIVER) (NEW)
19. Crusoe (MCRUSOE)
20. Efficeon (MEFFICEON)
21. Winchip-C6 (MWINCHIPC6)
22. Winchip-2/Winchip-2A/Winchip-3 (MWINCHIP3D)
23. AMD Elan (MELAN)
24. GeodeGX1 (MGEODEGX1)
25. Geode GX/LX (MGEODE_LX)
26. CyrixIII/VIA-C3 (MCYRIXIII)
27. VIA C3-2 (Nehemiah) (MVIAC3_2)
28. VIA C7 (MVIAC7)
29. Intel Core 2 (MCORE2)
30. Intel Core i7 (MCOREI7) (NEW)
31. Intel Core 2nd Gen AVX (MCOREI7AVX) (NEW)
32. Intel Core 3rd Gen AVX (MCOREAVXI) (NEW)
33. Intel Core AVX-2 (MCOREAVX2) (NEW)
34. Intel Atom (MATOM)
Last edited by graysky (2013-01-16 19:14:09)

graysky wrote:Practically, why do you need more than a few frequencies? For example, you're idle. I would want the lowest freq. You're under load. I would want the highest frequency. For situations in between, say launching a program, or moving data, whatever, an intermediate frequency would be fine. What do you hope to achieve with a more refined list of available frequencies?
I agree, your CPU, in practice, is really either idle or loaded.
In my case (AMD 965, 4 freq steps) the processor is at lowest freq for about 90 - 95% of a time, and at highest for 5 - 10%. The 2 intermediate are used for about 0.1% of a time.
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Hi,
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Speed measurement with PCI6601

I am building an application for measuring two linear encoders ( micrometers ) and one quadrature encoder for measuring speed of one motor.
At the moment I can read the two linear encoders with the "position measurement" option for the PCI6601.
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Could anyone have any easy solution for doing this?
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Massimo Visintin

Massimo,
A few notes in no particular order:
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A buffered measurement will give you much better precision, but you may be better off starting with a simpler unbuffered approach when getting started.
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Note that with this method, it's best to run unbuffered to avoid the lock-up problem you saw. It'll also be simpler to add your second speed-measurement counter task in the future.
4. Again, there *are* solutions available involving precise buffered measurements. I recently posted a DAQmx-based example that includes an instant-response buffered read (toward the end of this thread.). But I'd recommend first getting a simpler approach to work, then coming back to the buffered measurements later when you're sure you need more precision.
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How to measure transfer (speed) of internet connection with TC

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Speed can be measured through the normal web apps that test your internet speed.
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