Moved to Chinese board
↧
VS2017版 结构体数组生成dll 在labview中一直不能执行，直接崩溃退出？
↧
Why is the generated wave frenquency diffrerent from the set frequency in the program?
Hi all,
I hope to use triangle wave and a step wave to make galvo mirrors do a x-y scanning, and used a timer to inspect the scanning time for an image. But something wrong with the wave generating. When the wave (for x signal) frequency set in the program is 1HZ, the frequency getting from a oscilloscope is 5HZ. Also, no signal from Y axis's output can be detected by the oscilloscope. Can you help me about this?
The test vi is attached.
Many thanks,
Mei
↧
↧
For LabVIEW,How to pass parameter to WIN API function when it have a callback function as parameter
For LabVIEW,I want to use the WIN API function“ BOOL EnumWindows（WNDENUMPROC lpEnumF，unLcPARAM lParam ）”，but the parameter "lpEnumF" is an pointer to an application-defined callback function(EnumWindowsProc), how pass the parameter to lpEnumF in LabVIEW?
,
↧
Extract numbers from string output
Hi
I would like to know what is the most efficient way (in terms of execution speed) to extract the red highlighted numeric values from this string output:
1536x1103 0.83X 32-bit RGB image 85,85,85 (748,668)->(844,859) [213.77,296.68°].
I have attached a sample vi. Is this an efficient way to code it (in terms of execution speed)?
- Sable
↧
Problem in configuring and initializing FPGA
Hey, I have a Problem in initializing my FPGA, any suggestions?
Attached the real time and intializing VI
↧
↧
DAQmx Digital Input and Output and monitoring a specific channel
Hi,
I am trying to create a program a simple reaction time program that displays a boolean on screen for the user after an X amount of time. The user performs an action (button press) when the LED appears. The features of the program are:
1) Has 3 AI channels - biosignal, button device, and input from the AO channel
2) Has 1 AO channel - this will trigger an external stimulator device and also trigger a change in the third AI channel (0 to 5V)
3) Once the third AI channel has changed to 5V, the boolean appears and the program stops after a few seconds.
I can't seem to get the boolean to appear and am not sure I am monitoring (or even programmed this correctly) and I am looking for some help. The specific MH state is "SRT Predictable" and "SRT Unpredictable". I have looked around but haven't found a solution that fits exactly what I am looking to do on the forums. This program is a subVI within a much larger program so I have only attached the subVI.
Any help would be greatly appreciate. Thanks in advance.
Anton
↧
Use signal value to initiate sequence/event
Hi,
I'm trying to figure out how to use an analog input value to initiate an action/event/sequence. An example would be if I have a thermocouple and a water pump, and I want labview to automatically turn on the pump whenever the thermocouple measures a certain temperature or greater.
So I have been digging through the support pages and forum, but I think the problem is I'm searching for the wrong terms (I have not found what I'm looking for in triggering and timing pages). I'm just looking to get pointed in the right direction. Any help is appreciated.
↧
Exporting Data to an Excel File
Hello, I am currently trying to export data from a Keithley 2100 Series Digital Multi Meter (DMM) in the form of a 1-D array into an excel file automatically. I have tried using both the 'Write to Measurement File' and the 'Write Delimited Spreadsheet' functions, but both uses seem to generate the following error:
"Error -375701 occurred at Write To Measurement File->Keithley 2100 Series Read Multiple.vi"
The error description that follows is:
"LabVIEW: The Excel file is not generated by LabVIEW."
Both functions are giving me this error, and there seems to be zero documentation of this error on the National Instruments website. I was able to get around this issue at one point, but the destination excel file would be blank and would provide an error message that the excel file needed to be restored. I have attached a couple of PNGs of the basic set up for the my specific use of the functions. I made the file path a control for both, but I've tried using them as indicators as well and I get the same error in both cases.
Thank you, and I appreciate any help!
↧
Display values of array elements in DSM (Distributed System Manger)
In the DSM help it says that in a watch list (or directly in the process tree) it will not display the individual values of the elements of an array. I have two questions: (1) is there a way around that (short of modifying the code and putting an indicator there), and (2) it seems that this is not always true. Here is a screenshot of the 'Current value' view - I can clearly see the individual values if an integer array shown. We need this for a one-time examination of the values of a double array, which are shown in the front panel with insufficient precision. I was hoping that the DSM will show the full values. Thanks!
↧
↧
Imaq match pattern 4
Hi everyone,
I am currently working on an application using pattern matching. Now, the goal is to find and calculate the position of a marker (2D) on the index finger in real world coordinates. The marker can be freely chosen, let's say a white square double-sided tape with a black circle on it. Then I made a template of this marker and with 'IMAQ Find Pattern 4' the marker is identified and with the calibration template image the real-world coordinates are calculated. Everything works fine.
An important characterization is that there is always only one marker in the image, meaning that the output node 'Number of Matches' of the 'IMAQ Find Pattern 4' has a maximum of one in every image/frame of the camera. Thus, if it has found one, there is no need to complete searching all the other pixels of the image. Therefore, I have two questions:
- Therefore, is it possible to instruct of configure the application is such way that analyzing the image can stop after it has found a match (the match)? This should speed up a lot.
- Which search algorithm (Low Discrepancy Sampling, Grayscale Value Pyramid, Gradients Pyramid) is best for such a marker?
I hope someone can help me with this or point me in the right direction.
Btw, I am also using a Region Of Interest already to reduce search area, but this are still a lot of pixels (around 500 x 700).
↧
Hydrophone and NI DAQ
Hello,
I need information if NI DAQ'S 9205 and 9263 can be used with Bruel & Kjaer 8103 hydrophones to record data in Labview. I am also using CCLD converter with the hydrophone but I dont have a data acquistion system so I would like to know If i can use these DAQS.
↧
Trigger Parallel Loop from Event Structure
Hello all. I am very new to LV, so bear with me. I know I can probably clean a lot of this up with Arrays, etc., but I will improve as I get it working.
So, I have a program to control a 4 channel power supply, and by clicking a button, I want to be able to record the Voltage and Current on each of the channels at a regular interval, and simultaneously write the values to a .csv or .txt file.
So, where I currently am, I can start the recording, but then it seems that I get caught in some sort of loop, as I am unable to stop the recording. If I hit Stop and restart the program, then it won't start recording the next time, but if I click on the Abort button, then it will start recording, but then never stop. I initially had my recording loop within my case structure, but read that is not doable. I looked into various state machines and the producer/consumer method, but not sure if this is what I need.
Can someone give me insight on what I am doing wrong?
Thanks,
Mike
↧
How to update a single control in a cluster, referenced by index?
Hi,
I'd like to programmatically change control values in a cluster, referencing the controls by index (alternatively by control label). The attached code works, but seems ridiculously complex for such a simple task. I'm sure there's a better way. Any suggestions would be appreciated.
Thanks,
Martin
↧
↧
Display Problem with Time-Frequency Spectra
I was just handed a .WAV file containing some utterances, and asked to determine the frequency spectrum so we could order appropriate speakers to play the sounds. Because they are short utterances (a 4-5 second example is below), I decided to use the Short-Time Fourier Transform (STFT) code to create a Time-Frequency Spectrograph. I'd not done this previously, so I installed the Advanced Signal Processing Toolkit, ran some of the Time Frequency Analysis examples, read the Help files, and went to work. My (partly-successful) code snippet is below (the problem isn't the analysis, It's the Display, Dummy):
I read a Sound File, extract the (only) left channel, and run it through the STFT routine. I scale it using the Configure Spectrogram Indicator, specifying to Use dB and Ignore Timestamp (and providing a Reference to the Time-Frequency Spectrogram Indicator, an Intensity Graph, that it produces.
When I first did this, I started with a copy of one of NI's Examples, and got a nice Spectrogram. I started editing NI's code, replacing it with my own and simplifying somewhat (see above), but wiring it to the Indicator that came with the Example (why not?). As you can see, below, I got a nice picture.
So far, so good. So I added a second spectrogram (for comparison), but this time I right-clicked the output from the Configure Spectrogram Indicator VI and chose "Create Indicator". This gave me the second plot above (I used the same data here, of course). So what's the problem?
Notice the Amplitude Indicator, the little Rainbow Bar shown to the right of Spectrogram #1, but missing in Spectrogram #2. I've been looking all over for this, and can't figure out where it is. I've compared (by hand) many of the Properties of the two Intensity Graphs (using LabVIEW to examine all of the Z-Scale properties), and haven't found where they differ, but clearly they do.
One other thing is annoying me -- in the Block Diagram, the Label for Spectrogram #1 (the one I "borrowed" from the LabVIEW Example) has a box around it. I may have known at one time how to "box" such a label, but I've forgotten, and can't get rid of the box! [This seems almost too trivial to worry about, but it bugs me ...].
Just so I don't have Bob_Schor yelling at me about not posing Pictures (I'm sure he'd be OK with Snippets), I'll also attach the code, with "Make Current Values Default" (which I hope preserves the Pretty Pictures).
Bob Schor
↧
Get frequency of measured square wave
I have a sensor that outputs a square wave of voltage, and the quantity I'm trying to measure is given by the frequency of the square wave. Is there a way for me to find that frequency in Labview?
↧
OS and Network Services: (Hex 0x8ABC7009) Object already exists.
I'm trying to deploy my shared variables library to a cRIO target and I'm getting "OS and Network Services: (Hex 0x8ABC7009) Object already exists." and 'Deployment is completed with errors'. Now I can't run my VI. Anybody knows what this mean and how to fix it?
↧
NXG code conversion inserting incorrect default constants
I ran across this when testing if a LabVIEW bug had been fixed in NXG. The original LabVIEW 2018 code is below, and contains a call to Sound File Read Simple VI.
After this code is converted to NXG 3.0 with the code conversion utility, a bunch of compatibility (?) code is automatically added, which includes a sequence structure and wiring up previously unwired inputs. See the screenshot below.
The problem (apart from looking ugly) is that the automatically created constants are not the default constants for this VI. Specifically the samples/channel input default is -1 when unwired, but the conversion utility has wired up a constant 0. This has the knock on effect of always failing to load the wav file, as 0 samples/ch is invalid (error 61 is thrown indicating not enough memory is available).
Also worth mentioning is that the code conversion report didn't indicate any problems or issues with the VI in question.
Source for both is attached. Is this a known problem?
↧
↧
plotting a realtime graph in labview
I have taken data from arduino mega ADK board to LabVIEW and I am able read it.But if I donot include delay I get timeout error in READ (VISA) and I need the data to be read as a single array one after the other.And please help me to plot the data in realtime.
↧
misrepresentation frontpanel with internet explorer 11
same server (crio),
two clients
what ist wrong on client one? Both with internet explorer 11.
All updates ok.
I've no idea.
↧
configure Ni 9219 with excitation
Hi, I am working with a project, where I want to collect data from different types of sensors and handle everything from the front panel.
I have set up a 3wire linear potentiometer to my Ni9201 with an external voltage supply and my programs runs like i want.
But when I try to connect the potentiometer to my NI 9219 and want to use the internal voltage at the module, i can't figure out what i am doing wrong.
Can someone please tell me how to wire up my potentiometer and how to configure the excitation in my Labview program?
Best regards
Morten
↧