Seperating signals

Hi,
i have a big problem with labview 7.1
I have a Data-Tanslation DT 300 A/D-Card, and i want to measure with 3
seperate channels. I have a VI where almost everything works, but i
can´t find, where i can seperate the channels. The only icon i found
does not have an output, so i can´t store and draw the channels seperatly.
I hope you know what i mean, and i hope i get answers because i am very
desperate at this moment.
Bye Aeron

You need to provide a little more information on the functions from DT that you're using. Their acquisition VI must be returning a signal in some format. If it's a 2D array, then you can use the Index Array function to get either the row or column that represents a specific channel. Attaching the actual DT VIs that your're using would help. Also, since it's DT code that you need to use, have you tried asking them about your problem?

Similar Messages

Averaging values of multiple signals seperately

Hi All,
I am attempting to create a VI that will average data over a user defined amount of time (via boolean switch). The attached vi collects data once the "collect Data" switch has been triggered, when the test is over the user triggers the "average collected data" switch to get an averaged value. Please see attached VI.
THis vi works fine for a single signal. However, the ultimate goal is to be able to do this whole process for n-number of sensors throughout my test loop with a final output as an excel file.
I am pretty sure that I can get the data saved for an excel file but I cant figure out how to get all of the signals averaged seperately and placed into an array.
Any help will be much appreciated!
Thanks,
Stefan
Attachments:
Average Collected Data.vi ‏13 KB

Stefan,
When you are doing the multiple signal process, will the collection time and averaging be done for all signals simultaneously or will there be separate Collect and Average controls for each channel?
If all channels will be done simultaneously, you can probably just make your arrays 2D with each channel in a different column. Each iteration of the loop will store the data in the next row (if Collect is True).
Notes on your VI: 1. You do not need the sequence structure. Dataflow controls when things happen. Your VI will work the same without it.
2. The two case structures wired to Collect Data could be combined into one.
3. Building an array inside a loop results in frequent memory reallocations. As the array gets large this will cause the program to slow down and will fragment memory. A better approach is to allocate memory outside the loop with Initialize Array and use Replace Array Subset inside the loop where the Build Array primitives are now. You will need to add another shift register to keep track of the next index to replace.
4. Loops should usually have a time delay to prevent them from grabbing all the available CPU cycles. Once you put in a real data acquisition process, that may provide the delay.
Lynn

Seperating Multiple Signals in the same band.

Overview of the problem:
I have a quite complicated filtering application here that I could really use some help and insight on. I'm trying to extract a repetitive signal (a pulse) that is not cyclical but appears on certain modulus. (Meaning a pulse could come 2 to 5 modulus after another.) This places the signal in a certain band, we'll call it the I band, as in the signal of interest. Now there's a bit of background noise, repetitive, cyclical, but varies in phase and frequency slightly over time. (This is caused by a mechanical device!) The device creates one signal with a very strong amplitude, that has it's principle energy in about 4 different bands. The first is slightly lower than I, the next is I itself, and the next two are slightly higher than I. We'll call these principle frequencies A,B,C, with I appearing after A and before B in order of increasing frequency from left to right. Now while A,B, and C are particular and fairly constant to this device, that is certainly not true of similar devices that will be encountered in the future, so any method of filtering must be adaptive. My goal is to eliminate A,B,C (if need be) and subtract that portion of signal that is caused by any other signal except for the signal of interest in the band I. The presence of the second signal overall gives me a signal to noise ration of about -12dB.
What I've tried so far:
Traditional linear filters, even if they're adaptive, appear to be totally out of the question. Their attenuation of the band I, also results in the attenuation of I itself.
I can quite easily lock on to the cycle of I, create an average of it's cycles, and subtract an approximate guess from the current cycle. This produces mixed results.
I've tried using independent component analysis, but this technique seems to rely on the fact that the two signals are in separate bands.
Using a short time fourier transform, I can generally see the change in the I band due to my signal. I have also achieved similar results with the continuous wavelet transform.
Where am at now:
At this point I could really use some community input as to how to handle this. I'd love to hear if anyone has had the same problem, has any suggestions, knows of any literature that could help me, or anything at all.
Thank you very much for your time.
Regards,
Ken

Hi Ken,
Would it be possible to send a screenshot of all the signals on a graph? I'm having trouble envisioning what you mean by "bands." Do signals A, B, and C occur on certain moduli as well? Are they the same amplitude and frequency as I?
Also, what are you trying to accomplish overall?
Message Edited by Pakman on 06-10-2008 06:01 PM
Peter K.
National Instruments

How to check 6 digital signals change value at the same time with PCI-6229??

I am using DAQ card PCI-6229.
Channel 1 generate a digital signal.
Channel 2,3,4,5,6,7 acquire digital signals.
I want to check:
1. Whether the rising edge of Channel 2,3,4,5,6,7 occures at the same time;
2. The time delay from the rising edge of Channel 1 to the rising edge of Channel 2,3,4,5,6,7 is within a certain range.
I know I can use counter to get the two edge seperation time delay. But I only have two counter, it is two time-consuming if I check one by one.
I don't know how to check the rising edge of 6 different channels occure at the same time.
Does anyone has any suggestions?
Thanks

Hello,
You can use the DAQ card's digital input change detection circuitry to detect changes in the input, you can then use a counter to measure the relative time between samples. Please read Page 6-9 DI Change Detection Applications for more information. Let me know if this helps
Christian A
National Instruments
Applications Engineer

How to send an analog output signal on same axis running a stepping motor umi 7764/ PCI7334

I am running a single axis stepping motor (which is working fine) but
for the application I need to be able to turn on and off a 5 volt
laser. It notes in the manual for the UMI 7764 that the the
analog output can be used as a general-purpose voltage output. I
would like to use it as such, but can't figure out what VI's actually
send messages to the board to output a 5 Volt signal.
Ideally I would use the analog output on the same axis that the
stepping motor is on, but if need be I could use one of the other axis
if this isn't possible (ie. it may not be possible to step and send
analog voltage output on same axis at same time). I have been
looking at the configuring DAQ and ADC stuff, but can't seem to make
sense if these actually control the analog output channel. I
think they just control the Analog input channels, but maybe I am
wrong.
Any help would be greatly appreciated
Andre

Hi,
It is possible to send analog output out of the same same DAC channel in which your stepper is connected, if you configure the stepper as open loop in MAX. I've tried it. This way you have the stepper output, analog output and encoder input acting independently. So you can use these seperately for different purposes, such as using the analog output for constant speed motors where speed or position control is not of much importance, encoder for positioning some other axes and stepper output for stepper control. With good programming skills, the NI motion controllers can thus be used for the most complex configurations. Great work NI !!! Nothing is impossible.
Regards,
Giridhar Rajan
Automation Engineer, Design
Cruiser Controls
Mumbai, India

NI 6602 measure quadrature encoder with two signal edge sepearation

Is it possible to improve the position measurement for X4 encoders,
that the measurement starts at start trigger and stops at the stop
trigger signal like the normal two signal edge seperation measurments.
Everything I tried don't works. Does anyone have an idea. Thank You
for Your trouble.

Hello Yong,
You have no wait time within your for loop. This means that the loop will execute as fast as possible, but not at a constant rate. To acheive a more constane rate, try inserting a Wait Time of 1 ms. This will get you a loop with a 1 kHz rate.
How fast is your PWM Signal? It may be that you are missing some two edge measurements while waiting for the loop to iterate.
I suggest merging your error clusters out of the DAQmx Read.vis. Right now, you are just clearing out any errors. Let me know if you start returning any errors once you have done this.
Regards,
Sean C.

Unsupported video signal 42TL515U

I have a 42TL515U 3d tv n when i connect my sky cable box with recording feature to the tv, i get a big box that says unsupported video signal at the bottom of the screen... Its really annoying as the picture also becomes dull.. The box disappears for some time while one operates the volume controls n other controls on the remote. But returns after a couple of seconds. Please help n tell me how shud i connect the sky recording box to it. Currently i have connected rgb cable to colorstream hd1 n ryw cable for sound seperately to in video 1 audio port hdmi. Please guide me how to connect so that i wont get unsupported video signal again..

Is this issue bcoz i m using a US made tv in india.. Signals are different i guess... Ntsc pal systems are different... Shud i buy a converter so that the signal is first converted to US type n then maybe the big gray box will disappear.. Pls someone reply as asap...

How to generate two signals using NI myDAQ

Dear Sir:
I designed a circuit to generate a sine wave successfully using Labview. What I want is using NI myDAQ to generate another 3V DC signal as a power supply. I can do this seperately but when I add them together there is an error: NI Platform Services: The specified resource is reserved. The operation could not be completed as specified.
I would like to use A01 to generate a sine wave and A02 to generate a DC wave, could you please check my file and tell me how to solve this problem. I found a solution which generates two signals together but what I need is to control these two signals seperately and using two channels.
Kind Regards
Jeff
Attachments:
signal gen and acquire.vi ‏126 KB

Thanks very much for your kind reply.
No. I tried for a long time, change the samples of each simulate signal to the same but the warning also came out. Could you please check my file and tell me how to solve this kind of problem?
Kind Regards
Jeff

How to introduce dead time in analog signals?

Hi, I'm new to LabVIEW and I want to introduce a dead time in the analog signals that I have attached in this post. The time difference varies, so I could not introduce a time delay in the signal
for instance, the attached waveform, i want the first signal to be seperated from the second signal. so i got 2 different signal at the end of the day for analysis. during the no signal time no signal is not recorded.
thanks in advance for all the help
Attachments:
Time delay.JPG ‏37 KB

Hi skydew,
It is possible to introduce a delay in an analog output. This is best done by specifying a trigger and then beginning the output when that trigger occurs.Below is a link to an example program developed for LabVIEW that waits a specified number of seconds and then triggers analog output to begin.I think this is what you mean as dead time.Take a look at this example and try to build from it for your code. If you have any further questions on this issue, let me know.
Analog Input with Delayed Analog Output
Also see some links below:-
http://forums.ni.com/t5/LabVIEW/Finding-the-time-delay-between-two-signals/td-p/2125100
http://forums.ni.com/t5/LabVIEW/calculating-time-delay-between-two-signals-aquired-from-DAQ/td-p/849...
Thanks as kudos only

I have a net gear wireless router and a APE working great inside the house, but the wireless signal is weak in the backyard, can I get a net gear extender for the back and it will also send my music to the airport express?

I have a net gear wireless router and a APE working great inside the house, but the wireless signal is weak in the backyard, can I get a net gear extender for the back yard and it will boost our wo
Ireless signal and also send my music to the airport express? Or does the airport express work as a stand alone hub?

Trust me when I say this coming from 20 years of experience.
Get a powered external drive, format it 1 Partition Option: GUID and OS X Extended Journed as the format in Disk Utility.
Download and install Carbon Copy Cloner, clone internal drive to external drive.
Set a schedule to remind you to do it at least once a week, keep it near your charger.
When you plug your charger in, do plug the clone and power the machine up, set the display to sleep only,
CCC will do the rest.
If you want to boot from it, hold the option/alt and select it Startup Manager.
I've seen many TimeMachine and TimeCapsule nightmares and so far haven't seen a problem from anyone using a bootable clone.
It's simple, it's easy, it's more reliable and more powerful than what Apple does and it only takes plugging in a extra cable.
Make as many clones as you want, keep them time seperated, off site etc. etc.
Cables don't have network issues, clones can be verified in seconds merely by booting from them.
Clones protect your productivity, your up in seconds on a clone despite even the hard drive dying.
Software problem? No sweat, boot of the clone and reverse clone your problems away.
If you want to fuss and muss with half implemented TimeMachine and TimeCapsule network headaches then prepare to suffer.
I don't like to suffer, I bought a Mac not to suffer, but it appears you do with TimeMachine and TimeCapsule.
Most commonly used backup methods

TIO Edge Seperation 6601

I don't know what I'm doing. I need to calculate a machines running speed. I am using 1 counter to track the number of pieces run. I was told by someone (who can no longer give me further info) that I need to: "Measure speed: configure counter 2 with frequency signal of 100000, calculate speed using 36,000,000 per hour(or was it second?) as base." I found the TIO Edge Seperation VBP example and I'm trying to use it as a start. But if I change the frequency from anything but the '20,000,000' it originally has, it returns nothing. Also, the documentation says that if I set buffer mode to continous, the CWCounter1_AcquiredData event will be fired every time the value of NMeasurements is reached, but it is only firing once. I'm new to this, pl
ease help.

Hi GearRunr,
One of the ways counters calculate speed is by counting the number of pulses it receives in a known period of time in the case of multiple events. You can also calculate speed or frequency of a device by measuring the number of pulses of a known frequency occur within a portion of the signal.
The best way to get started is to use the shipping examples with NI-DAQ (driver for the 6601 card). If you are using VB, you should have installed support for VB when installing NI-DAQ. You can also modify your installation now to include support for VB by going to Add/Remove Programs and modifying the insatllation. Once you have support installed, you should have shipping examples installed in the National Instruments/NI-DAQ directory.
Since c
ounters can measure and generate pulses, we will need a combination of both to take speed measurements. You will want to configure one counter (counter 0) to generate a pulse of known width (1 second for example). Then you would connect this output to the gate of a second counter. The gate effectively turns on or off the counter when it is counting. So if you connect your signal to be measured to the source of this counter the counter will count the number of pulses that occur in 1 second (in our example). Therefore if you read 2,500 counts, you know your speed is 2,500 counts/second.
Anyway, I've included a simple example that uses VB and the CW controls to count edges. Many times, you would only need to right-click on the control and adjust the counter properties through that method instead of programmatically adjusting them in code. Hope that helps. Have a good day.
Ron
Attachments:
DAQSTC_Event_Counting.zip ‏4 KB

Two Edge Seperation / PCI-6238 / Error -200140

Trying to use a PCI-6238 card to measure the time between Digital Inputs rising or falling. From what I was directed, this should be able to be done via the Two Edge Seperation Task... However, when I configure the task it seems that no matter what the Min. and Max Time I set, I get the error:
<<<<
Error -200140 occured at MyTwoEdgeSeperationTask - DAQ Assistant
Possible Reason(s):
Two consecutive active edges of the input signal occurred without a counter timebase edge.
Use a faster counter timebase.
>>>>
I can I change the Counter Timebase?? I thought the system selected the optimum counter timebase based on the Min and Max value entered in..
Thanks for any help.

Not at hw to test, but here are some brief thoughts anyway:
1. Error message sounds a little odd to me, almost like it's only looking at 1 input signal rather than 2. Could simply be poor choice of error text though...
2. There's a property called "Duplicate Count Prevention" that is frequently relevant to situations where the signals to be timed are faster than the timebase used to time them. If you search the forums for that term, you'll find more detailed info. The summary is that it can either be enabled or disabled and the behavior when the inputs are too fast are either to produce an error like yours or to return a measurement of 0. (I honestly don't know which setting does which -- it's easy enough to experiment and find out though).
3. The timebase can be chosen explicitly, though DAQmx should indeed have picked the appropriate one for your specified Min / Max. You'd probably want a Min of 0 and a Max that's less than about 50 seconds. My guess: DAQmx *did* pick the appropriate timebase, and the error text suggesting you use a faster one is just generic advice that doesn't actually apply to your case.
4. Two Edge Separation requires you to know which signal will come first. If you don't know which one will come first, you may still be able to accomplish your goal by setting up a "change-detection" DI task and then measuring the period of the change detection pulse signal with a counter. I know this would work on the 5V DIO versions of the M-series, but I'm not so familiar with your particular board.
-Kevin P.

Have more than 2 groups in Mixed Graph Signal

Hi is it possible to have more than 2 groups in Mixed Graph Signal . I would like to graph my analog signals seperately like digital signals in Mixed Graph Signal but seems like I can have only 2 groups. 1 for digital and for analog. Is it possible to add another analog group so I graph my each analog signal in one group
Thanks

Hi,
This discussion has come up in a couple of previous posts:
http://forums.ni.com/t5/LabVIEW/Mixed-signal-graph-Group-update/td-p/471000
http://forums.ni.com/t5/LabVIEW/Programming-a-Mixed-Signal-Graph-s-Plot-Area-Name/td-p/1288066
There still isn't any property node that enables us to do this programmatically.
Thanks and Regards
Supreeth.K
Applications Engineer
NIUK

Loss of signal when tv turned on

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I have an airport express about 40 ft away extending the signal to the other side of the house.
There is one computer hard wired into the extreme in the office.
Everything was working perfectly until a few months ago when we started to loose the signal, mostly in the late evening. This isn't an internet issue because the hard wired computer is just fine during these times.
We finally realized it corresponds with when our flat screen tv is turned on in the bedroom across the hall from the office. The wifi is perfectly fine if you are standing within the office or surrounding bedrooms, but as soon as you walk down the hall 5 ft, there is only a very, very weak signal and the express can't extend anything.
I've tried changing channels, moving around the location of the extreme, and nothing works. The tv is not connected to the internet and there are no components attached to it. iStumbler finds nothing when the tv is on and Charter says there's something wrong with the extreme, not with their wiring or signal and not with the tv.
The weird thing, is that this was not a problem until a few months ago. Before that, the tv and internet were working perfectly fine together...it pretty much started having problems over night.
Does anyone have any suggestions? It's very frustrating and I'm out of ideas.

Everything was wired by Charter and they've come out 3 times to check the lines. There is a splitter where the line enters the house and it is split and all are connected by cables for each of the bedrooms and living room (4 rooms/TVs total) for cable tv and then one for internet in the office.
I initially thought there was something with the line when the cable tv is running (and it's definitely the cable box that is the issue, not the tv as I've tested this with the tv running and the cable box seperately and it only drops when the cable box is running), however, speedtest on the desktop wired into the airport extreme are consistent whether the tv is on or not. It only affects the wifi.

WRT54G2 slows computer receiving wireless signal

Basically, i got a desktop computer connected to the modem n router with a laptop and ps3 receiving the signal. Internet works fine on all 3 seperately but the problem only occurs when the desktop computer is on the internet. When its on, the internet on the laptop works but is very slow and receives constant 'the connection has been reset' errors in the browser and also has trouble signing in to msn. With the ps3, the internet doesn't work at all with the desktop on the internet. Anyone know wuts wrong??

Upgrading the router's firmware might help you...Download the Firmware from here , Follow these steps to upgrade the firmware on the device: -
Open an Internet Explorer browser page.In the address bar type - 192.168.1.1
Leave the username blank & in password use admin in lower case...
Click on the 'Administration' tab- Then click on the 'Firmware Upgrade' sub tab- Here click on 'Browse' and browse the .bin firmware file and click on "Upgrade"...
Wait for few seconds until it shows that "Upgrade is successful" After the firmware upgrade, click on "Reboot" and you will be returned back to the same page OR it will say "Page cannot be displayed".
Press and hold the reset button for 30 seconds...Release the reset button...Unplug the power cable from your router, wait for 30 seconds and re-connect the power cable...Now re-configure your router and check if your problem is resolved...

Seperating signals

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