求助: 如何使用write to spreadsheet file.vi 和 read from spreadsheet file.vi, 并且如何定义它们的路径???

请问如何使用write to spreadsheet file.vi 和 read from spreadsheet file.vi,我知道spreadsheet file.vi只支持.txt文件,但我应该在哪里设置它们的路径呢,请各位帮忙指点,能不能具体说明下,谢谢...

write to spreadsheet file.vi 和 read from spreadsheet file.vi,支持.xls文件.
可以在path处设置它们的路径.

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Read an avi file using "Read from binary file" vi

My question is how to read an avi file using "Read from binary file" vi .
My objective is to create a series of small avi files by using IMAQ AVI write frame with mpeg-4 codec of 2 second long (so 40 frames in each file with 20 fps ) and then send them one by one so as to create a stream of video. The image are grabbed from USB camera. If I read those frames using IMAQ AVI read frame then compression advantage would be lost so I want to read the whole file itself.
I read the avi file using "Read from binary file" with unsigned 8 bit data format and then sent to remote end and save it and then display it, however it didnt work. I later found that if I read an image file using "Read from binary file" with unsigned 8 bit data format and save it in local computer itself , the format would be changed and it would be unrecognizable. Am I doing wrong by reading the file in unsined 8 bit integer format or should I have used any other data types.
I am using Labview 8.5 and Labview vision development module and vision acquisition module 8.5
Your help would be highly appreciated.
Thank you.
Solved!
Go to Solution.
Attachments:
read avi file in other data format.JPG ‏26 KB

Hello,
Check out the (full) help message for "write to binary file"
The "prepend array or string size" input defaults to true, so in your example the data written to the file will have array size information added at the beginning and your output file will be (four bytes) longer than your input file. Wire a False constant to "prepend array or string size" to prevent this happening.
Rod.
Message Edited by Rod on 10-14-2008 02:43 PM

Wiring write to spreadsheet.vi to read from spreadsheet.vi and plot the data

I need to plot the data file from the two 'write to spreadsheet.vi' into a graph. Does anyone know how should I connect the 'read from spreadsheet.vi' so that I can plot my data?
Please refer to the snippets.
Thanks.
Attachments:
read from spreadsheet.png ‏31 KB

Hi Lynn,
You're asking the very same question that I've been wondering about because I don't have the time info. I've found an example that have both info, temperature and time in two colums in one file..it uses two Index Array for time and temp, use the bundle feature, display the plot in an XY graph. So, that was an easy one, but apparently my case is different.
I've a program that collected the data from simulated signals and it is plotted in a waveform graph against time (amplitude vs time), and a power spectrum (amplitude vs frequency). But the data that I collected are the RMS values and power spectrum amplitude...so, I'm not sure where the time data go. I need to figure this out.

How to open saved files using 'read from text file' function

Hi everyone, I am having a hard time trying to solve the this particular problem ( probably because I am a newb to lanbview ). Anyway , I am able to save the acquired waveforms by using the 'Write to text file' icon. I did manually modify the block diagram of the 'Write to text file' icon and create the correct number of connector so as to make my program work. But now I have no idea on how to modify the block diagram of the 'Read from text file' block diagram to make my program 'open' my saved waveforms. Or i do not have to modify anything from the block diagram of the 'Read from text file'? Can anyone teach/help me connect up? Do i need the build array on the "open" page?
Here are some screenshots on part of my program
let me know if you guys would need more information / screenshots thank you!
Attachments:
ss_save.jpg ‏94 KB
ss_open.jpg ‏94 KB
modified_writetotextfile.jpg ‏99 KB

Ohmy, thanks altenbach. oh yeah i forgot about those sub VIs. will upload them now. Was rather demoralized after reading the comments and really struck me on how weak i'm at on labview really hope to get this done. But of course i have to study through and see how it works. Actually i am going to replace those 'signal generators sub vi' with ThoughtTechonology's sample code so i can obtain data waveforms real-time using Electrocardiography (ECG) ,Electromyography (EMG ) and Electroencephalography (EEG) hopefully i can find out how to connect the sample code.
( ps . cant connect it now unless my program is working otherwise labview will crash )
( p.s.s the encoder of my biofeedback trainer already acts as an DAQ so i wont need to place an DAQ assistant in my block diagram i suppose )
The sample code of ThoughtTechnology is named as attachment.ashx.vi. too bad i cant use it and present it as my project
Attachments:
frequency detactor.vi ‏53 KB
signal generator.vi ‏13 KB
attachment.ashx.vi ‏40 KB

求助: 还是一个如何使用write to spreadsheet file.vi 和 read from spreadsheet file.vi, 并且如何定义它们的路径的问题???

在定义路径时有两个路径框,一个是FILE PATH,另一个是NEW FILE PATH,请问我应该定义哪个呢???定义好后就可以直接往spreadsheet file.vi中存储和读取记录了吗???还需要再做任何其它的工作吗???谢谢...

定义file path就可以了，new file path 是这个VI的输出

How to read two text files using the Read from spreadsheet.vi and then plot it

I need to read two text files using the read from spreadsheet function and then plot these files over time.
The file with the .res extention is the RMS values (dt and df) and the second file contains the amplitude of a frequency spectrum.
I really appreciate any help..thanks
Attachments:
RMS.txt ‏1 KB
FREQUENCY.txt ‏1 KB

From NI Example Finder:
Write to Text File.vi
Read from Text File.vi
Jean-Marc
LV2009 and LV2013
Free PDF Report with iTextSharp

Read from spreadsheet file

Hi! I am a beginner labview user and I have a problem reading data from a
..xls file. I have written in columns the data that i want to present in a
waveform graph through labview. I give the path to the Read From Spreadsheet
File tool and i connect a true constant in the "transpose" terminal. The Run
button shows me no error but all I get in my waveform graph is a x-axis
line. Could someone help me? Thanx

You say that you want to read data from a .xls file. You use Read From Spreadsheet File to get the data into LV.
You have mixed some things. A .xls file is NOT a spreadsheet file. It is a file which could be read by MS Excel and some other tools which have import filters for this file. Read from Spreadsheet File is not such a filter.
A spreadsheet file in the context of LV is a text file where the cells of a row are separeted by a tab and the rows are separated by a end of line.
A save thing is use Active-X automation to communicate with MS Excel. Let it load the file and read out the cells. The are examples in LV help and in the dev zone. You must have installed and licenced MS Ecxel on your target machine. Maybe someone has written such a fil
ter for LV but I don't know it.
The other way will only work if you use US local settings and the data is in one worksheet. Save the file with the extention .txt. So Excel will generate a text file of the correct format. Excel will use the regional settings of your machine. You can read in this file with Read From Spreadsheet File. Unfortunatly this will use fixed settings which are the same as for US regional settings.
Waldemar
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

EOF detection in "Read From Spreadsheet File"

Hi folks, I need help in detecting EOF in a "Read From Spreadsheet File". I' d like to stop a while loop by wiring the EOF? indicator to the stop condition, but this doesn't work. For design resons I can't substitute the while loop with a for loop and I DO need the while loop. I read something about creating custom EOF detection but I'm wondering why the builtin function in the vi doesn' t work and if there isn't some simple solution. Many thanks, hazibuli

I'm guessing that you want to process one line at a time from the spreadsheet. Use Read From Spreadsheet File to read in the entire spreadsheet as Dennis says. Then wire the 2D output to a For Loop with indexing enabled. Each iteration of the For Loop will allow you to process one line at a time. When the last line is processed, the For Loop will exit automatically. Here is an example to get string length of each element in a spreadsheet. Message Edited by tbob on 03-15-2010 09:46 AM

Read from text file vi won't read file...

I am very new to LV programming so I hope you forgive any stupid mistakes I am making.   I am using Ver. 8.2 on an XP machine.
I have a small program that stores small data sets in text files and can update them individually or read and update them all sequentially, sending the data out a USB device.   Currently I am just using two data sets, each in their own small text file. The delimiter is two commas ",,".
The program works fine as written when run in the regular programming environment. I noticed, however, as soon as I built it into a project that the one function where it would read each file sequentially to update both files the read from text file vi would return an empty data set, resulting in blank values being written back into the file. I read and rewrite the values back to the text file to place the one updated field (price) in it'sproper place. Each small text file is identified and named with a 4 digit number "ID".   I built it twce, and get the same result. I also built it into an installer and unfortunately the bug travelled into the installation as well.
Here is the overall program code in question:
Here is the reading and parsing subvi:
If you have any idea at all what could cause this I would really appreciate it!
Solved!
Go to Solution.

Hi Kiauma,
Dennis beat me to it, but here goes my two cents:
First of all, it's great to see that you're using error handling - that should make troubleshooting a lot easier. By any chance, have you observed error 7 when you try to read your files and get an empty data set? (You've probably seen that error before - it means the file wasn't found)
If you're seeing that error, the issue probably has something to do with this:
Relative paths differ in an executable. This knowledge base document sums it up pretty well. To make matters more confusing, if you ever upgrade to LabVIEW 2009 the whole scheme changes. Also, because an installer contains the executable, building the installer will always yield the same results.
Lastly, instead of parsing each set of commas using the "match pattern" function, there's a function called "spreadsheet string to array" (also on the string palette) that does exactly what you're doing, except with one function:
I hope this is helpful...
Jim

"read from measurement file" reads only first line of data

Hello,
I have a problem when trying to read a .lvm file through "Read from Measurements file" with the following block diagram
Problem: it reads only the first line of data from what I can see in the probe window,.
A part of the lvm file for reference.
I haven't used Labview in a long long time, I'm trying to figure out what I am doing wrong.
Thanks

Sorry meant to attach the lvm. Here it is. (Actually I had to put it in .txt because the forum wont let me upload a lvm file)
I unfortunately cannot share the full vi that record the data as I am not its owner/creator. I'll try to give as much info as I can with the relevant pictures attached, I hope it allows us to at least have an hint of where the problem might be.
(this is in a while loop)
In the stacked sequence, the other pannels are similar to the one shown here: value read fron a variable, converted to dynamic and a signal attribute is set. The "start recording" control operation is "switch when pressed".
Here are the properties of the set signal attributes
And here are the properties of the "write to measurement file"
Attachments:
NoTarget_full circle__Rx_-10-SAMPLE.txt ‏60 KB

Read from spreadsheet: a way to automatically continue if the file is missing? (Rather than having to push "continue")

Hi,
I'm using the "read from spreadsheet file.vi" to read in data from a file that may or may not be present. The data isn't required - it's optional data; nice to have but not everybody will use it.
Of course, if the file isn't present, I get an "Error 7 occurred at Open File+.vipen File", and I have the choice of pushing either the "Continue" or "Stop" button. What I'm wondering is: is there a way to just have LabVIEW automatically continue if the file is missing? Perhaps it could alert the user to the missing file, but continue anyway? Normally I'd handle this by wiring the Error output of the function to an error indicator. But the "read from spreadsheet file.vi" function doesn't appear to have an error output.
I think my description of my question is sufficient, but I'm attaching a snippet of my LabVIEW code that shows the read from spreadsheet file function in question, and the error I get when the file is missing.
Thanks,
dan
Solved!
Go to Solution.
Attachments:
labview-read-sprdsht-error.png ‏27 KB

Dan_the_Clam wrote:
Why oh why do people hate them so much! I'm a friend of local variables!
1. They use more memory
2. They require something on the front panel (even if hidden). So that is yet another copy of your data
3. They break data flow
4. RACE CONDITIONS!!!
Dan_the_Clam wrote:
my code evolves and tends to sprawl a bit.
That tells me you do not have a good architecture to begin with. It also tells me you need to modularize your code more and use subVIs.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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Read From Spreadsheet File help

I am saving all my data to a text file (See attached file). The problem is that when I try and use the Read From Spreadsheet File.vi I am unclear on how to make it show all my data.
Does anyone know a away for me to read the whole file and display it all at once reather than line by line?
Solved!
Go to Solution.
Attachments:
test data 1.txt ‏6 KB

The read from spread sheet Vi has two data outputs : the top right retrieves the whole file as a 2D array, if you leave the "number of rows" input on the left unwired.
Message Edité par chilly charly le 01-07-2009 11:22 AM
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

For Mike Porter: Read from Spreadsheet File.vi" function

On 2/17/03 you answered my question about reading and viewing a test done last week back into Labview. I can open the "Read from Spreadsheet File.VI" in Labview and read the file "data.txt" into the VI. The data comes back into the rows & cells on the VI screen but I don't know how to open the graph to see the data as curves. I can see about a 3 x 4 array of cells at a time and the correct data is there but I want to plot it. Do I need to create a new block diagram and VI? I apologize for the vagueness of my question - I'm new at Labview.
Attachments:
DATA2.TXT ‏183 KB

Create a VI with a Waveform Graph on the front panel. On the block diagram, insert a Read From Spreadsheet File function. Connect the All Rows output to the Waveform Graph.
Attachments:
Graph.jpg ‏3 KB

Format precision apparently ignored when using read from spreadsheet file

I hope there is ridiculously simple solution to this problem but so far I can't find it. Using the Read from Spreadsheet File function in LabVIEW7.1, I can't get the floating point format (%f) to work; the decimal (%d) seems to work fine. For example, the first value in the attached file is 399.5853. When I read it in using %.2f format I would think I should get 399.58 but instead I get 399.58529663... Oddly if I use %d as the format, I get an as expected value of 399. Can anyone see what I am missing?
Attachments:
ReadFileTEST.vi ‏23 KB
test.txt ‏1 KB

The solution to the problem is the internal representation of floating point numbers: with a limited number of bytes only a limited number of the (infinitely many) real numbers can be represented. The nearest representable number to 399.5853 is 399.58529663 if the so-called single precision representation (abbr. SGL in Labview) is used.
It seems that (ridiculously!) NI has chosen to use SGL as the data format in the Read from Spreadsheet VI which causes the unexpected behaviour you observed.
You can change the representation from SGL (which uses 4 bytes) to DBL (double precision, using 8 bytes) in the Read from Spreadsheet VI and you will observe a better approximation then, but still not 'exact' since the number now reads 399.585300000000018. (With t
he EXT representation, 10 bytes, you could go to even higher precision)
I hope someone from NI reads this and they fix the unnecessary limitation of the precision in the Read from Spreadsheet VI.

Read From Spreadsheet File.vi in windows 7

Hi,
I use Read From Spreadsheet File.vi in windows 7 to read a table, but when it executes, i get a dialogue box asking for the filename, (The box is properly wired to the path).
However, when i execute exactly the same programme in windows Xp it works with no problem.
¿Any known issues with this vi and xindows 7?
I am using labview 8.6.
Thanks for your help.

I am using a relative path as shown in the figure, files are user1.xls user2.xls .... they all exist.
I have build the program and instaled on other xp machine, it works. Then installed in a win 7 machine and is not working.
Maybe there is a problem with ..\..\?
Any other way to go to a parent folder not using ..\ ?
Thanks for you help
Attachments:
ejemplo.JPG ‏8 KB

求助: 如何使用write to spreadsheet file.vi 和 read from spreadsheet file.vi, 并且如何定义它们的路径???

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