Generate signal with variable pulsewidth and period

Hallo,
I want to generate a square signal where I can modify the pulswidth, period, amplitude, frequenzy, duty cycle...at the Front Panel.
I also want to be able to generate just a a single puls/period on the one hand and a puls-train on the other.
I´am working with a AT-MIO-16E-1(DAQ-Card), a SCB-68 and LabView 7.
I`d be very grateful, if anyone is able to help me...
Thanx a lot...
Greets Daniel

Daniel,
It sounds like you are trying to generate digital pulses using your DAQ board. The counter output is designed to be a digital signal. That is, the amplitude of the signal is either 0 V or +5V. Therefore, the amplitude cannot be controlled.
However, there are some great examples in the LabVIEW Example Finder that will help you implement your two options.
Access the Example Finder by navigating to Help >> Find Examples... Then go to Hardware Input and Output >> DAQmx >> Generating Digital Pulses. There are several examples there which you can check out to get you started. The most interesting to you are likely Gen Dig Pulse Train-Continuous.vi and Gen Dig Pulse.vi.
I hope this gets you started in the right direction.
Stephen Meserve
Applications Engineering
National Instruments
Stephen Meserve
National Instruments

Similar Messages

Generating signal with several frequencies - Timing issues

Hi
I use Labview 7.1.
I am trying to generate a signal composed of 1000 different frequencies.
For this purpose I am using the Multitone Generator VI .
My problem is that the generating process is too long for my real-time
application.
Is there any way to accelerate (optimize) this process?
I think about several options, such as:
Using more powerful computer (multicore)
Making the process parallel (is it relevant
for Labview7.1?)
Changing VI's properties (priority etc..)
Please advice
Amir

Hi,
Attached my problem.
I am trying to generate signal with 100 frequency component (100 different sine waves).
According to the timers it is taking 87mSec to produce the signal which length is 1 second.
In my project, I need to generate 1000 frequency components. And also 20 channel of this kind.
So it is clear that i will not be able to achieve the timing requirements
(It will take more than 1 second to generate a signal of 1 second)
What can you advise me ?
Thanks
Amir
Attachments:
Generate_100_freq_signal.jpg ‏156 KB

Acquire generated signal with this hardware ?

Hello everyone,
I didn't really know where to post this, I apologize if it's the wrong place.
I'm very new to the LabView thing, and I have for project to trigger an injector and so to create a digital signal like this:
Due to the characteristics of the signal (110V, 10-20A, injection duration: ~20ms), someone recommended me this hardware (sorry if I'm not allowed to post these links):
- programmable power supply: http://fr.farnell.com/ea-elektro-automatik/ea-ps-9200-25-2u/alimentation-1-voie-200v-25a-prog/dp/2422474
- USB interface: http://fr.farnell.com/ea-elektro-automatik/usb-interface-ea-if-u1/interface-for-psi-el-usb/dp/1268147?ost=EA-IF-U1
I'll try to figure out on how I create (on my own for now) the signal with LabView.
My question is, will I be able to acquire the generated signal with this hardware in LabView, do I need something else ?
Thanks.

I have designed and built injector drivers. To get a waveform somewhat like the one you showed requires a sophisticated and fast control circuit. I would not call that a digital signal. It may be controlled by some kind of logic signals, but that is an analog signal. No programmable power supply I have seen is fast enough to come close.
The pull-in current does not typically go into a ring/overshoot flat-topped waveform as you have shown. It follows an exponential curve defined by the L/R rise time and the current limit set by the supply voltage and the injector coil resistance. For the injectors I have seen that current limit is much higher than the current required to generate the magnetic field required to open the valve. That oscillatory response could be the result of a switch-mode current regulator.
Similarly, the hold-in current does not occur by magic. Either the supply voltage needs to be changed (open loop system) or the current sensed and regulated (closed loop system). The kind of ringing you show can occur in a switch-mode current regulator.
Lynn

How to compare a Date data with Current Year and Period Member on FIX

Hi experts,
I have a Project dim that each member is a Project (P01, P02...)
and Account dim that stores information of the each Project (Name, Start date, Finished Date...)
Finished Date member is in Date data type
So how can write a IF condition below in order to compare Project Finished Date with Current Year and Period members on FIX
FIX (@Descendants(Projects), Descendants(All Year), Descendants("Year Total")...)
IF (@CURRMBR(Period)->@CURRMBR(Year) < Project->FinishedDate)
Do something...
Else
Do something
Please help me on this. Sorry for my bad grammar. Please ask if there is anything unclear
Many thanks,
Huy Van.
Edited by: Huy Van on Jan 29, 2013 1:14 AM
Edited by: Huy Van on Jan 29, 2013 2:24 AM
Edited by: Huy Van on Jan 29, 2013 2:25 AM
Edited by: Huy Van on Jan 29, 2013 6:04 PM

Here is what I have done. Post for whom may concern later
VAR FM; /* Finished Month of Project*/
VAR FY; /* Finished Year of Project */
VAR CM; /* Capture Current Month on FIX statments */
VAR CY; /* Capture Current Year on FIX statments*/
FIX ( @RELATIVE( "Year", 0), @RELATIVE( "Period", 0), @IDescendants( "Base Projects")....)
FY = @ROUND( "TGHT"->"NA Contract"->"FY06"->"NA Period" / 10000, 0);
FM = @MOD( @ROUND( "TGHT"->"NA Contract"->"FY06"->"NA Period" / 100, 0), 100);
/* For FY13 return 13... */
CY = @JgetDoubleFromString( @CONCATENATE( "20", @SUBSTRING( @NAME( @CURRMBRRANGE( Year, Lev, 0, 0, 0)), 2)));
/* Set CM value based on currrent Period On FIX statement */
IF ( @ISMBR( "Jan"))
CM = 1;
ELSEIF ( @ISMBR( "Feb"))
CM = 2;
ELSEIF ( @ISMBR( "Dec"))
CM = 12;
ENDIF
IF ( CY < FY OR ( CY == FY AND CM < FM))
Do something...
ELSE
Do something...
ENDIF
ENDFIX
Edited by: Huy Van on Feb 19, 2013 11:10 PM
Edited by: Huy Van on Feb 20, 2013 7:46 PM

Better estimation of phase difference between two signals with variable frequency!

Hello LabView Gurus,
Being a power engineer and having just a little knowledge of signal processing and labview, I have been pulling my hair out for the last couple of days to get a better estimation of phase difference between two signals.
We have two analog voltage signals; 1. sine wave (50Hz ± 1Hz) and 2. a square wave with exactly half of sine wave frequency at any time.
At the starting point of operation (and simulation/acquisition) both signals will have no phase difference. However, the square wave's frequency changes unpredictably for a just a few millisecond but then it gets synchronized with sine wave's frequency again. This means that the square wave will be phased out from its original position. The task of the labview is to find the phase difference between the two signals continuously.
My approach to determine the phase difference is to measure the time when sine wave crosses zero amplitude and the time when the very next square wave changes amplitude from zero volts to +ve voltage (I have a 0.5volts threshold just to avoid any dramas from small line noise). The difference between these times is then divided by the time period and multiplied by 360 to get this phase difference in angles.
As this part is just a small block of a big project, I can only allow 5000Hz sampling rate each for both signals. I read 500 samples (which means I read data from 5 cycles of sine wave and 2.5 cycles of square wave).
Now the problem is, as long as the frequency of sine wave stays constant at exactly 50Hz, I get a good estimation of the phase difference but when the frequency changes even a little (and it will happen in the real scenario i.e 50Hz ± 1Hz and the square wave's frequency is dependent of sine wave's frequency), the estimation error increases.
I have attached my labview program. From front panel, you can set the phase of square wave (between -180 and 0) and you should see the labview's calculated phase in the indicator box named 'Phase'. Then you can press 'Real Frequency' switch that would cause the frequency to change like it would in real operation.
You can observe that the estimation error increases after you push the button.
All I need to do is to reduce this estimation error and make it as close to the actual phase difference as possible. Any help would be greatly appreciated.
I am using LabView 2009 for this task.
The application is for electric machines and the stability/performance of machines under different faults.
Thank you for reading this far!
Regards,
Awais
Attachments:
v603.png ‏320 KB
v603.vi ‏186 KB

Jeff Bohrer wrote:
Basic math gives me a bit of pause on this approach. You are sampling at 50 times the frequency of interest so you get 50 samples per cycle. your phase resolution is 1/50th cycle or 7.2 degrees +/- noise. You will need to samlpe faster to reduce phase resolution or average multiple readings (at a time cost that is signifigant)
Jeff- (Hardly Working)
I am sampling at 100 times the sine wave's frequency and 200 times the square wave's frequency. Increasing the sampling rate completely solves my problem. But since I am acquiring several other inputs, I cannot afford a sampling rate higher than 5kHz.
F. Schubert wrote:
I'm not a signal processing expert, but here my basic understanding.
If you simulate sampling with 5kHz and a frequency of 50 Hz (and both are 'sync' by design), you always get an exact 5 periods. Any variation of your signals frequency gives you a propability to get 4 or 6 'trigger' events. That's an up or down of 20%!
The one measure to reduce such problems is using 'window functions'. They don't fit your current approach (counting instead of a DSP algorithm), so this needs to be reworked as well.
My approach would be to use the concept of a Locki-In amplifier. You need to phaseshift your ref-signal by 90°. Then multiply your measurement signal with the ref signal and the phase shifted ref signal. The obtained values for x/y coordinates of a complex number. Calculate the theta of the complex number (with the LV prim). Feed this in a low pass filter.
The trick on this is, that the square wave has harmonics in it, in this you are interested in the second harmonic which is the sine wave.
To get rid of the effect that the sync between sampling rate and ref signal frequency gives an error, you then can use the window I mentioned above (place it before the lock-in).
For a design that really plays well, use a producer-consumer design pattern to get the calculations done in parallel with the DAQ.
I suggest you to check on wikipedia for some of the keywords I mentioned. Go also for the external links which lead to great tutorials and AppNotes on the signal processing basics.
Sorry, it's not a simple solution I offer and we will have quite some conversation on this forum if you follow this path. Maybe someone else knows a simpler way.
Felix
www.aescusoft.de
My latest community nugget on producer/consumer design
My current blog: A journey through uml
An interesting view. the sine wave can indeed be looked as a second harmonic of the square wave. I will implement your idea and get back to you as soon as I get some results. But since I have very limited knowledge of signal processing, it might take me a while to get my hear around the solution you mentioned.

Querying, then generating ArrayLists with variable names

Hi, all:
I have two problems: first, I want to run through an array list called nodeList containing Nodes, each of which possesses a 5-digit value called culture. I want each Node to try to find out whether or not there are any other Nodes that have the same culture value that it does, i.e. if Node i has culture value 74936 and there are 4 other Nodes with the same culture value, I need to find 5 total Nodes with culture value 74936.
public void statistics(){
       for (int i = 0; i < nodeList.size (); i++) {
            Node node = (Node) nodeList.get (i);
            int cultSame = node.getCulture();
            boolean same = cultSame == next.cultSame;
            if (same == true){
                 arrayListCreator();
                 //generated Arraylist add.node;
}I'm going astray at next.cultSame. I'm not sure how to structure the query to the ArrayList nodeList to find all the other Nodes with the same culture value.
Second: I want to create a little method to generate ArrayLists with names based on the integers that will be stored in them. Here's the method so far:
public void arrayListCreator () {
       String name = String.valueOf(cultSame);
       name = new Arraylist();
}cultSame is a 5-digit integer. The ArrayLists will be used to store all the nodes with the same cultSame value, like 74936, or whatever. If the ArrayList is storing nodes with the cultSame value of 74936, I want the name of the ArrayList to be the string 74936. I want to call on this method (like you can see in the first method) to generate the ArrayList with its given name and then use it to store the nodes in it. Once I've done that, I can figure out the statistics stuff on my own, I think. I'm just not sure how to create the ArrayLists with a name that's a variable, i.e. "name" should be the string variable containing a 5-digit number.

Nquirer101 wrote:
I probably should have separated this out into two threads. First, I'd like to know what I'm doing wrong when I'm building that boolean query to find out in the nodeList if any of the other nodes have the same culture value as the node doing the querying.Then by all means do so, from the looks of it, the scope of the thngs that need to be discussed/addressed is too broad for one thread. First there's the issue of your erroneous understanding of variable, then there's the concept of the Map data structure, then the implementation of it in Java, along with the idea of interface

Bookmark with Variable screen and UserExit

Hi
We're using the bookmarks in portal of N2004s.
If someone starts a bookmark it's possible to bring the user first to the variable screen. But I recognized that the userexit is not activated for some variables after changing them.
concret:
I called a report with time-selection week = 10.2007 - the report has keyfigures which are restricted by a userexit variable which is previous year (calculated by time selection - 1year) - so the report shows me the keyfigures with previous year 10.2006 and 10.2007 - I save this as a bookmark.
calling the bookmark with this link: &bookmark=46LQ49TMUQ8BRH3O91VEH0XMK&variable_screen=X
the bookmark shows me first the variable screen. The user can change then the time-selection. But when i change now the time-selection in the variable screen from 10.2007 to 20.2007 I get in the report stll 10.2006 and 20.2007.
So it seems to me the bookmark doesn't run through the user exit to fill the variable "previous year".
How can this be activated?
Thank you for your reply.
Roger

Hi
I debugged now the user exit and it seems as following:
- calling a bookmark with selection_screen=x but without the parameter clear_variables=x does run through the user exits step 1 to 3 before showing the variable screen. After changing a variable the user exit is only enabled for step 3 and not anymore for step 2 - that's why the previous year is not updated.
- calling the bookmark with selection_screen=x and clear_variables=x runs user exit with step 1 before selection screen and then after entering variables step 2 and 3 - and the previous year is filled correctly. But this is not useable, because the user want's to have selection variables prefilled.
Has someone an idea how to bring the bookmark without clear_variables=x to the point to run the step 2 in user exit after changing variables in selection screen?
Thx
Roger

Generate URL with oas,oapc and ti

Hi all,
I am trying to generate a url with oas oapc and ti and pass to javascript for navigating back to that page. When I don't give these parameters I Get the error as You are trying to access a page that is no longer active.- The referring page may have come from a previous session. Please select Home to proceed.
I used some function createURL or something to do this before. But now I totally just cant get this work.
Can someone pls help?
Thanks in advance.

Please update your exact requirement in the post.
What you need? Why you need?
don't mention "ti" parameter in the URL,
BTW, what value you are passing in this?
Are you aware of the importance of this parameter?
-Prince
[email protected]
http://princekapoor82.blogspot.com

IdeaCentre K450 "no signal" with monitors (VGA and HDMI)

I purchased a K450 (from the lenovo online outlet, refurbished) in December. I got an Acer H226HQL 21.5" monitor at the same time, and set up everything at once. I used the VGA cable to connect the monitor. Everything was working perfectly until a couple weeks ago. I went to wake up the computer and the monitor remained black. I pressed the power button to turn it off completely and turn it on again, "no signal" stil on the monitor. I've tried using the HDMI cable with the acer and the 8 year old monitor from my last desktop (with VGA cable) and still no signal. Checked the power strip, it's working fine. I'm at a loss!
I did run updates on firmware for everything, including the graphics, when I set up the computer. I'd check on the firmware for the graphics card, but it's hard to without a working monitor. Also, not sure if it's relevant at all, but it was running windows 8.1.
Is there anything else I can do to fix this?
Thank you!!
Solved!
Go to Solution.

Problems like waking up from sleepmode, black screen and other problems start appear after MS released their January 2014 updates. Also timing what you say your problem began make sense to January updates. Check also this topic:
http://forums.lenovo.com/t5/IdeaCentre-Desktops-Home-Servers/K450-dvi-no-signal-after-power-manageme...
Hope this help!

No video signal with docu cam and projector

School teacher's Thinkpad connected to avervision document camera, and document camera to an overhead projector. Image throught the projector of what's under the document camera is fine. When we want to project what's on the computer screen (movie, etc.), and switch to "computer" on the document camera, the laptop screen goes black, but the projection is visible through the projector. Is there an FN fix or some other way to fix this?

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I can't find anything like that in the 'Select output processing'-box, even after updating to 9.7.8 (released on Friday)...
It doesn't make any sense to me. Why would it work with AE and BM Media Express but not with Premiere CC?
My BM Decklink is not the newest model, but I don't think thats the problem.
It still seems to be supported by the software and it works with AE.
I'm going to change my graphic card from GTX 780 to NVIDIA quadro, lets see whether that will get me the result I'm hoping for, but tbh I'm giving up...

Product type for securities with Variable interest and unit quoted

Hello,
Somebody knows, Wich product type can I use to manage securites, where I could calculate variable interest at the end of the month and calculate purchases and sales by units?
I try to use 04H with this product I can calculate the variable interest at the end of the month but I can't used to purchase or sale with units.
Thanks for your help,
Adriana

Hi Ravi,
I followed your instructions.
In SPRO->Treasury and transaction management->Transaction management->Securities->Master Data->Product types->Condition types. I created the followed condition types:
999 Variable interest TZST
998 Int. rate adjustment 999 ZA
Then in Created a new condition grup (99) and assing the Conditions types: 999 & 998 to the group 99
I Created a new product type Z43 and assigned the condition group 99
Then in,
In SPRO->Treasury and transaction management->Transaction management->Securities->Position Management->Securities Account Management->Update Types->Assign Update Types to Condition Types
In Active Pos:
999 Variable interest TZST Incoming payment with positive position 5009 (incoming)
Thanks,
Best regards,
Adriana

Fast busy signal with incoming calls and unable to connect to voice mail

We are using CISCO 2821. The system started to have problem connecting to voice mailbox (when dialing internally to the VM extension) and it used to take a reboot to bring it back. Now it will not connect to voice mail (gets fast busy signal), plus incoming calls get a fast busy signal after the first ring tone. To make it worse, the Call Manager Express web page does not load. Does anyone have any idea how to solve the problem? Thanks!

Called ATT...they verified the problem and said it was an intermittent signal problem....
only issue is I have to keep the phone off to make sure I received voicemails....
Definitely NOT an iPhone problem, but an ATT problem.

How to correct "An incompatible audio signal" with Apple TV and HD signal

I have an Apple tv2(mc572Ll/a) running version 4.4.4 of the software, connecting to an older Sharp Aquos LCD-26d6u TVvia a regular HDMI cable.
I used to be able to watch a rented movie until my onsitel technician/ teenager adjusted something.
Now when the preview plays the sound works. When a video is displayed using AirPlay from the iPhone the sound works.
But when the HD movie plays the message "an incompatible audio signal has been received. Check the output device settings" and there is no sound.
When I connect this to a newer HDTV the movie sound works.
Any suggestions on what Apple tv or tv settings to use to get the sound back (other than upgrading my technician/teenager/tv)?

Thanks! I changed the Dolby setting from On to Auto, and the sound started working for Netflix TV shows. Before I was getting the message:
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and there was no sound.
The Settings are accessed through Apple TV.   When you have Apple TV on, and you see all the colored rectangles for Netflix, huluplus, HBO etc., (which can be accessed by repeatedly hitting the Menu button on the remote), the top row shows:
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Use the 4 way controller to choose Settings, then press the button in the center of the 4 way controller to select Settings. Then select Audio Video. Then scroll down to Dolby Digital. When you are on Dolby Digital and you push the button in the center of the 4 way controller, the setting will change. I changed the Dolby Digital setting to Auto.

Pieces with variable lengths and Packing

We have a scenario where a fabric is received from production in rolls and after quality it is cut and stored in multiple pieces with multiple lengths. We need to identify each piece individually.
After storing, these pieces are then packed in different handling units i.e. pallets, rolls, bales, etc. depending on the customer order instructions. These are then stored for delivery. The requirement is to identify each handling unit along with the individual pieces packed so that it any given time it is viewed how much fabric is available in pallets and pieces for delivery.
Please let me know how this can be handled in MM.

Thanks For your reply guys,the above mentioned Scenario has been catered and it in the following way:
I did it with the help of multiple level packaging.
I actually considered the Piece length as a Packing material .
Then In Hu02 select the material to be packed and the mention the partial quantity as a length and pack it in considered packing material.
And then in Pack HUs tab select all the piece lengths to be packed and click on (NEW HU Per*H) and enter their the final packing unit and pack it.The system allocate the handling unit and that is the pallet number.
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Query SQL with variables Parameters and user defined tables

Hi everyone
I got a problem about Query SQL
[dbo].[@CSOURCE] is a user defined table
select * from [dbo].[@CSOURCE]
you can get the result in following
code    name
T01      newspaper
T02      TV
T03      radio
T04      friends
when I execute the following SQL   Statements ，I get an error
SELECT T0.CardCode , 0.CardName ,T1.Name ,T2.SONumber
FROM OCRD T0    LEFT JOIN [dbo].[@CSOURCE] T1 ON T0.U_CSOURCE = T1.Code
                             LEFT JOIN (SELECT T0.CardCode ,COUNT(T0.DocNum)SONumber
                             FROM ODLN T0 INNER JOIN OCRD T1 ON T0.CardCode = T1.CardCode
                            WHERE T1.GroupCode =111
                            AND   (T0.DocDate >=[%0] or [%0]='')
                            AND   (T0.DocDate <=[%1] or [%1]='')
                            GROUP BY T0.CardCode) T2 ON T0.CardCode=T2.CardCode
WHERE T0.GroupCode =111
and T0.CardType ='C
Is there anyone can correct it for me
thank you very much
Edited by: Li Mishan on Jul 17, 2008 9:36 AM
Edited by: Li Mishan on Jul 17, 2008 9:40 AM

I am sorry .It is just a mistake of my typewriting.
The following is the whole SQL
dbo.@CSOURCE is a user table.It's content is
code name
T01    newspaper
T02    TV
T03    radio
T04    friends
declare @m int
declare @FromDate DateTime
declare @ToDate DateTime
set @m=(SELECT count(*) FROM ORDR T0 WHERE T0.DocDate >=[%0] and T0.DocDate <=[%1])
set @FromDate=[%0]
set @ToDate=[%1]
/*****************If I do not connect user tavble dbo.@CSOURCE ，I will succed *****************************************************/
SELECT T0.CardCode ,T0.CardName ,T2.SONumber,T1.Name
FROM OCRD T0 LEFT JOIN [dbo].[@CSOURCE] T1 ON T0.U_CSOURCE = T1.Code
                           LEFT JOIN (
                                            SELECT T0.CardCode ,COUNT(T0.DocNum)SONumber                                            FROM ODLN T0 INNER JOIN OCRD T1 ON T0.CardCode = T1.CardCode
                                            WHERE T1.GroupCode =111
                                            AND (T0.DocDate >=@FromDate or @FromDate='')
                                            AND (T0.DocDate <=@ToDate or @ToDate ='')
GROUP BY T0.CardCode
                                        ) T2 ON T0.CardCode=T2.CardCode
WHERE T0.GroupCode =111
and T0.CardType ='C'
when I excute the SQL, It return a error , whith says the column name '%0' is invalid.
If I delete "set @m=(SELECT count(*) FROM ORDR T0 WHERE T0.DocDate >=[%0] and T0.DocDate <=[%1])"
and rewrite "set @FromDate='2008.05.01' set @ToDate='2008.07.01' "
It Shows the following results
   CardCode     CardName     SONumber     name
1      000070        Deng. Jiahua   1                newspaper
2      000293        LU .Weijuan    1                radio
3      000313         Xie .Jifang       3               TV
Edited by: Li Mishan on Jul 18, 2008 4:42 AM
Edited by: Li Mishan on Jul 18, 2008 4:43 AM
Edited by: Li Mishan on Jul 18, 2008 5:43 AM

Generate signal with variable pulsewidth and period

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