Display FFT of input signal which receive from VISA read ?

Hi.
I receive data from MCU whcih sampling frequency is constant and we assumed it is S. now I get data from MCU with using VISA read block. I can display data, perform some functios like filtering, multiply and save them in txt files. all thing is OK.
but when I want to see FFT of incomig data on chart , it doesn't work !! I use this VI for calculate and display FFT of input signal (from VISA read) and display it which in Y-Axis is magnitude and X-Axis is frequency.
in your mind why this is not work and what I must done for show input signal FFT and frequency components ?
Thanks.

If I understood this correctly, you are getting the correct results when outputting to a text file but you are not able to see the results when trying to output to a chart?
This discussion may be of some help to you.
Rob S
Applications Engineer
National Instruments

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Plot data following receiving from VISA

Hello,
I am reading data from a microcontroller using VISA function in labview. I can convert these data to decimal values (this is what I want).
I want to build a X-Y graph in this way:
Every time I receive a value from VISA, I want to put this value on the graph (Y value) with respective number of reading (X value).
For ex. if the first time after reading VISA, I receive 128, I want to have X=1, Y=128 on my graph. If the second value from VISA is 154, I want to have X=2, Y=154, etc...
Could you please help me how to do that.
My main concern is how to build the X axis.
Thank you very much.

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Dear,
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I try digital count, also digital input with timestamp but not be able to catch them correctly.
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Hi there,
If you want to do the edge counting for any purpose
You can try with DAQ assisant function and setting the Counter Input section as Edge Counting
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Text strings from VISA read don't match identical looking text constants - could it be double byte characters"

Our RS232-enabled instrument sends ASCII strings to COM 1 and I read strings in. For example I get the string "TPM", or at least it looks like "TPM" if I display it. However, if I send that to the selector input of a Case structure, and create a case for "TPM", whether the two appear to match varies. Sometimes it matches, and measuring its length returns 3. Sometimes it measures 7 or 11 or 12 characters long, and it doesn't match. I can reproduce a match or a mismatch by my choice of the command that went to the instrument prior to the command that causes the TPM response, but have made no sense of this clue. I have run it through Trim Whitespace, with Both Ends (the default) explicitly selected. I have also turned the string into a byte array, autoindexed a For loop on that, and only passed the bytes if they don't equal 32, or if they don't equal 0, thinking spaces or nulls might be in there, but no better.
The Trim Whitespace function's Help remarks that it does not remove "double byte characters". But I can't find anything else about "double byte characters". Could this be the problem? Are there functions that can tell whether there are "double byte characters", or convert into or out of them? By "double byte characters", do they just mean Unicode?
Solved!
Go to Solution.

Cebailey,
The double byte characters are generally used for characters specific to languages other than English. If you display your message in " '\' Codes Display" in a string indicator do you see any other characters? You could also use Hex Display to see count the number of bytes in the message. You are probably getting messages with non-printable characters that might need to be trimmed before using your application. If you want more information the '\' Codes Display, there's a detailed description found in the LabVIEW Help. You can also find the same information on our website in the LabVIEW Help. Backslash ('\') Codes Display
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How to search/split a string from visa read

hello all, i have a string coming from the serial port... the pattern is:
\00\s\s\s\s0,\s\s\s\s12,\s\s\s\s\s0,\s\s\s\s\s0\r\n
where the data is read as 0, 12, 0 , 0. i would like to save this data into a Write to Measurement File, for which i have to convert this text data into decimal format. can anyone please suggest me how to reduce the data from the string? I know I can save the data in a text file, but i am limited to use the Write to Measurement FIle.vi
please help.
Now on LabVIEW 10.0 on Win7

Hello LV_Enthu,
Have you played around with the functions in the Functions palette>>String at all? There are a few helpful functions like search/split strings and match string pattern that can be helpful, but here is an example from our website as well that does just this. Please let me know if you have any further questions.
Thank you,
Deborah Y.
LabVIEW Real-Time Product Marketing Manager
Certified LabVIEW Architect
National Instruments

What does the number returned from VISA Read STB represent?

The value seems to correspond to ibsta, but I thought Read STB returned the status of the instrument, not the bus. If the former is the case, how can the instrument have a status value of 64 (REN/40 + CIC/20 + LACS/4) since it is a counter and is not capable of being the CIC. Any thoughts?
Thanks,
Chris

Read STB issues a *STB? command which retrieves the contents of the instrument's status byte register. Decimal 64 corresponds to bit 6 (RQS/MSS set). The device is sending SRQ. It is not the same thing as ibsta at all. Your instrument manual should have a section on it's status byte register.
And if it was ibsta, decimal 64 is still bit 6 only (2**6 = 64) and not bits 2, 5, and 6. REM, CIC, and LACS all being set would be decimal 100 (REM=64, CIC =32, LACS=4).

How to seperate two input signals

Hi people, currently i have one input voltage signal, i would like to add another input signal which display the temp from my Arduino IDE wirelessly via serial visa configure. After doing that, i would like seperate these two signals by using data bits. Can anyone explain to me in a detailed procedures?
i will upload up the file to show the current program that i am having now. One would be the main, the other would be the SubVI file.
Attachments:
Arduino Visa FG.vi ‏20 KB
Arduino Visa FGV SubVI.vi ‏26 KB

I can't tell you anything because you haven't shown me anything of what you are doing.
Show the subVI you've created. How are you merging them together? What does the data stream from your Arduino look like? Once we know that, then it will be easy to figure out how to split them apart.
I wouldn't go so far to see you have a temp waveform and a voltage waveform. It looks like you are just reading them a datapoint at a time. You almost always need to have a Serial Configure when dealing with serial ports. It doesn't matter whether you are reading both datapoints through the same serial port or just one datapoing through the serial port.

FOC items received from vendor...

Hi Experts,
I have a FOC item which receive from vendor. Which module i should use for good receipt? Goods Receipt PO or Goods Receipt?
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Regards,
Danny

Hi Danny,
Use Goods Receipt PO Document in Purchase Module.
In Goods Receipt PO Document Unit Price is entered as Zero.
*Close the thread if issue solved.
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Characters from VISA not in ascii

I am using ARM Cortex Microcontroller. I am sending the numbers into lab view through usb port.
In such case, the strings obtained from VISA Read are not ascii but i can convert them into unsigned int with the help of string to uint premitive.
The numbers to be sent are continuous and they consist of u8, u16 and also float values.
So the problem here is the conversion. only those value which are defined as u8 are displayed correctly.
How do i convert into appropriate values.
E.g. if the value is integer but greater than 255 i should be able to read and display.
If the value is float i should be able to display the proper float number.
I also tried with scan string premitive, also string to number premitive. They can only read ascii and convert, but the characters i am converting are not ascii.
The characters i am receiving look like boxes and for a value of 0 they are empty space.
To convert a number into ASCII in my microcontroller could also be possible but the requirement here is with lab view. Microcontroller currently has huge load of programs.
I would be happy if someone whould help me in this.
Thanks in advance.
Solved!
Go to Solution.

Sorry for the mistake to write it is string to byte.
The necessary clippings are as below. The second clipping 'read buffer' is from a series of transformation where, first data is 300, second is 1 and third is 1.23. The output for these as seen in the third picture is 44, 1 and 1. Yes, 300-256 = 44, previously i wrote 45.
According to you, do you mean that the first two byte should correspond to 300 ? and also similar for the float (not only one byte value but with several values in consecutive elements of the array)?
I would be happy if similar clips would be avialable.

VISA Read gets incorrect data from serial connection

I am having difficulty using the VISA functions in LabVIEW to read data from a virtual COM port. Data is being sent from a serial to USB chip via a USB connection using OpenSDA drivers. I have a python program written to read from this chip as well, and it never has an issue. However, when trying to achieve the same read in LabVIEW I am running into the problem of getting incorrect data in the read buffer using the VISA Read function.
I have a VISA Configure Serial Port function set up with a control to select the COM port that the device is plugged into. Baud rate is default at 9600. Termination char of my data is a newline, which is also default. Enable termination char is set to true. A VISA Open function follows this configuration, and then feeds the VISA Resource Name Out into a while loop where a VISA Read function displays the data in read buffer. Byte count for the VISA Read is set to 20 so I can read more of the erroneous datat, however actual data will only be 6-12 bytes. The while loop has a wait function, and no matter how much I slow down the readings I still get incorrect data (I have tried 20ms thru 1000ms).
The data I expect to receive in the read buffer from VISA Read is in the form of "0-255,0-255,0-255\n", like the following:
51,93,31\n
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51,193,128\n
And occasionally I receive this data correctly, however I intermittently (sometimes every couple reads, sometimes a couple times in a row) get incorrect readings like this:
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51,193739\n
\n
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I have search but haven't found a similar issue and I am not sure what to try from here on. Any help is appreciated. Thanks!
Attachments:
Serial_Read_debugging.vi ‏13 KB

The first thing is that none of the error clusters are connected so you could be getting errors that you are not seeing. Are you sure about the comm parameters? Finally, I have never had a lot of luck looking for termination characters. You might want to just capture data and append each read into one long string just to see if you are still seeing this strangeness.
What sort of device is returning the data? How often does it spit out the data? How much distance is there between it and your computer? Can you configure it append something like a checksum or crc to the data?
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

How to store the data coming from visa into file

Hi ,
I want to store the data into text file,which is coming from visa-read.
I tried visa read to file ,but it's not working.
Am new to labview plz help me out.
Thanks in advance.

CSFGF wrote:
Hi ,
I want to store the data into text file,which is coming from visa-read.
I tried visa read to file ,but it's not working.
Am new to labview plz help me out.
Thanks in advance.
Share the code you have so far with us so that we can check what's going wrong.

HT4437 Need apple tv input....i have a receiver with two zones. Zone 1 which is my surround which streams from my itunes fine but zone 2 to my deck, same input doesnt stream. Using digital opt in auxillary. Will i need apple express instead to play 2nd zo

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The vast majority of zone 2's on home theatre systems don't support digital audio.

I would like to tare (rezero) the input signal from a forceplate (glorified

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Maybe that is the limitation of Acquire Input Data.vi.The vi can't identify the Unformal key.
You can try to use Event structure and set to listen "key down" event.
There are two terminals VKey, ScanCode will sent out the information when you press key.
There are two pictures in attached file, 2.jpg will show you the detail.
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I am using USB - 6003 daq card.
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Attachments:
pulse_PLL.vi ‏27 KB

Hi AnkitG,
Here are a couple of links that might help you understand a little more how the PLL work and a way to synchronize the task to perform a PLL.
http://digital.ni.com/public.nsf/allkb/07BC8D77D4E9AE258625708B007CE74F?OpenDocument
http://digital.ni.com/public.nsf/allkb/2F675A9F2162EA24862572570059A308?OpenDocument
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http://digital.ni.com/public.nsf/allkb/EBD603683446EC13862575B3006A63A2
http://digital.ni.com/public.nsf/allkb/9E71F8D7D3CD1B0886257688004AE353
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Luis C.
National Instruments

Display FFT of input signal which receive from VISA read ?

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