Read in Binary form in VISA read function

Dear All,
I have connected my Device to the serial Port. and data read from the buffer is stored in text format. I want to view the data in binary format .
Actually, i have performed the same function in Visual Basic. there also if i view the data in text format, it shows some junk values. but if i view the data in binary, it shows the actual data coming from the instrument .
I dont know how to modify the VISA read function. can any one pls tell me how can i read the data in binary format?
Thanks
Ritesh

Oops! No it didn't.
Lab VIEW 2012 (if that makes a dif)
I'm using the VISA Read function to take ADC readings in from a microcontroller. The VISA Read function outputs the data as a string. Easy to convert the string to U8, either with the conversion function or type cast function, and works great except for a tiny corner case when the ADC reading is zero. The VISA Read function treats the 8-bit zero reading as a null character and strips it out.
Apparently, since this is done by the VISA Read function as it's building the string, type casting and or converting the output string from the VISA Read function doesn't "bring the zeros back".
I've tried setting the VISA property "Discard NUL Characters" to false, and that didn't seem to help.
My current work around is just to never have the micro send a zero ADC reading.
Anyway, I'm a Lab VIEW noob, so while this isn't essential to my project, I remain curious about how to send Lab VIEW serial data that isn't automatically considered characters, thrown into a string with all the zeros stripped out.
Regards,
Who

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Reading a binary file using the type cast function is not working

Hello
I am trying to read a binary file. Using the Read from binary file and type cast functions I can actually get the information from the file.
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Thank you for your reply,
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Reader extend pdf form in designer?

is it possible to reader extend a pdf form in designer?
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Hi,
It is not possible to reader enable a form in LC Designer.
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Is possible to save a form using Acrobat Reader? How to?

Hi all,
I designed a static pdf form using Livecycle. I want to send it to the form recipients, and I need they return me the pdf form filled. I can do this without problems on Adobe Acrobat Pro, but my mates that are using Adobe Reader can't save the filled form. Adobe Reader offers them to save a blank copy of the form or print it filled. But this isn't what I need. I need to have x copies of the form (of the pdf file) filled by my x recipients. Is there any option in Livecycle to allow saving the filled form on Acrobat Reader?
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Hi Enrique,
In order for users with Reader to be able to save your form, it has to be 'Reader Enabled' before you send it out.
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Can the carriage return within a variant be read as the termination condition for VISA READ?

Hi guys, I am trying to read a variant data using VISA READ. The VISA READ is set to terminate reading when it sees a carriage return.
Is there a chance that for the CR "encapsulated" within the variant be read by the VISA READ, and cause it to terminate?
Cheers!
Solved!
Go to Solution.

Since with the Flatten to String you are basically sending a binary representation of the data, you are going to have problems if you have the termination character enabled since byte 13 would be part of perfectly valid data and not just represent the end of a transmission.
What you might want to do is disable the termination character. Of course now you don't know how many bytes to read. So prepend your message to write with the number of bytes that are a part of the message (string length). You may want to use two bytes, (one byte would only give you messages up to 255 characters in length.)
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VISA READ STRING and GRAPH

I have some basic questions:
1. I have Serial communication from PXI to device. When I read the string of 26characters, continously, on Hypertermianl. It is fast enough. But when I read in the VI program, simple VISA read.
The reading is very slow. The VISA read one character at a time and take time to make a string of 26characters. Visa read is very slow, Why?
The baud rate is 1152K and rate is 32 updates per second, which is super fast in hyperterminal but very slow in Labview VI.
2. Second I need the extract the some data from my string at different positions on a string of 26 characters. I already made the subVI for reading it but since the VISA read is slow to read it gives wrong values from the string.
So I thought I can make an array and ask the subvi to read the the second (i.e n-1 value) 26 characters which are ready rather than first one which is being formed. But there is no arrays for string.How can I do that? also my concern is if I read n-1 value, it is not real time value.
:8 -0582                                n value Visa read slowly
:000000 -0076U 0008 -0582   n-1 value
:000000 -0074U 0008 -0582  n-2 value
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3. I will extract the 74, 76, 77 etc say the value as AA. I want to plot the graph of value AA versus Seconds? How can generate Seconds on my X-axis?
Attachments:
TSS1-porem-final4.vi ‏16 KB

Thank you for suggestion!
Now I am receiving data continuosly.
1. As mentioned previously, I wish to plot the heave value on real time basis, I saw the shipping example, modified my VI.
The plot is not correct, as the heave value increases and decreases linearly but there is strange graph.
2. Also I have one more question, actually if I want to find out the heave value, device once moved up 10cm and brought back to 0 level again. Its not instant as the design of the device says it takes 2 secs to get back to the zero state again. The heave is read from 10, 9, 8,7 6, 5, etc. It takes 10 steps to come back to normal value, zero value.
I just need to plot the 0 and 10cm or may be next might be -5cm, I need to capture the final data. How can i do that?
Attachments:
TSS1-porem-final4-1.vi ‏16 KB
MRU-TEST3-1.vi ‏20 KB

How to read data in binary form from file?

Hi,
i try to write an implementation of LZW. I need to read data in binary form from a file. How can i do that? I cannot find something like "binary input stream" ...
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Hi,
i try to write an implementation of LZW. I need to
read data in binary form from a file. How can i do
that? I cannot find something like "binary input
stream" ...
ThanksInputStream reads bytes. I don't understand your question.

VISA Read function Read buffer problem in serial communication

Hi, I use VISA write and read function in serial communication app, the device continuously sends 0x00 if it is not receive a request from Labview program running on PC.
And the request sent by labview is programmable. I met a weird problem, each time the request changes, the VISA read buffer output port still shows the last request firstly, from second time, shows the right request.
It works like: Req code: ... 50, 51,51,51,50....; VISA Read buffer: ...50, 50, 51, 51, 51, 51, 50....
Please refer to the program.
Attachments:
readOne_test.vi ‏21 KB

How are you running this? You don't have a while loop around it. Is it part of a larger VI? Please don't tell me you are using the run continuously button.
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"Read From Binary File" function Help ambiguity

I must be getting tired, but for some reason a doubt crept in my mind as I was designing a new piece of code this morning:
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"I used this function a million times and have always assumed it is reusing the last file position. Moreover, there is no file offset input to that function, so WTH am I afraid of?"
So, for kicks, I fired up the Help window and read the following description (*):
Reads binary data from a file and returns it in data. How the data is read depends on the format of the specified file. This function does not work for files inside an LLB.
(*) BTW, has anybody ever complained that you can't select and copy anything from the floating Help Window?
Not much there. I particularly admire the phrasing of the second sentence... What about: "This function can do a lot of things, but it would much to complex to describe this is extensive details, so if you are asking, you probably can't afford using it"?
Anyhow, I clicked on the "Detailed Help" and got this (among other things):
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WHAT? I am pretty darn sure I DO NOT USE the Set File Position when I read a file in successive and contiguous chunks. I just pass the file refnum into a shift register and back to the function and that's it.
Now, the description of the "Refnum Out" ouput says: If file is a refnum or if you wire refnum out to another function, LabVIEW assumes that the file is still in use until you close it. Translated in plain English, is that supposed to mean that if the file is not closed it is open, or is that implying that it contains more info that just "the file is open and can be found here"?
I started searching around and finally ended up with the entry for "refnums, file I/O". Down the bottom of the (long) article, I found this under the heading "References to Objects or Applications" (but nothing specific to files, BTW):
...LabVIEW creates a refnum associated with that file, device, or network connection...
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So, my point is: the Help File for this function is incomplete or ambiguous at best. Please correct it. And provide a link to the "refnum, file I/O" Help entry in its detailed Help. It would H E L P...
Thanks for reading.

Reading in succesive chunks is *NOT* random access. An open file always has
a current position, which is updated with each read or write operation.
You only need to set the file position if you want to start elsewhere.
LabVIEW Champion . Do more with less code and in less time .

Visa read function question

Hi, all:
I use Visa to write/read data from hardware through COM port, the protocol is interactive communication, labview send commnd frame first, then hardware send back required data frame.if labview don't send command frame, then hardware send 0x00 continuously. frame length is 10 bytes.
My idea is: use Visa Write to send one frame down, then inside a While loop a Visa Read to get the data frame, when get the right data frame, stop while loop.
But I found the while loop can't stop, with probe, I found the data frame sliped once, it seems that Visa Read get the data then very soon it get 0x00 so that the comparison function can't finish to handle the data, then 0x00 arrives to the probe which sticked the input terminal of comparison funciton.
I solved this problem use a buffer string to store Visa Read's output read buffer, and make Visa Write and Visa Read a pair inside the while loop.
I wonder why the comparison function can't catch the data frame from Visa Read exactly.
Please refer to the attchment jpg file, it is not the real vi, just illustration
Attachments:
visaRead.jpg ‏23 KB

Is it possible that your device is already sending 0x00 when you start running your VI? If so, you may get that in the serial port buffer. Then, when you do the VISA Read, you will read 0x00 as the first byte, then the first 9 bytes of your frame (cutting off the last byte) so the comparison won't work.
EDIT: by the way, it's common to read the "Bytes at Port" VISA property, then feed that into VISA Read as the number of bytes to read, so that you read the entire buffer contents. You can then scan that string for the expected data.

Reader plugin and form submit function inside a browser. *any help or idea please*

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Might be simpler to explain the ends i';m trying to achieve here.. I have a application form for a daycare saved as a pdf on the server, but as you know clicking the submit button from the browsers default viewer does nothing.. well i'm looking for a way to change that with out having to code the form or implement a bunch of script and databases.. script i can deal with but i dont want to set up a database that a user would then need to go to in order to acess the submited information.. I want the info once completed in the pdf to be emailed to the end user email address, still in a pdf that he can later on print or save in a folder for later use, I dunno.. but yeah I woulds like to avoid downloading of programs as much as possible..
How about removing the submit button from the form and placing it on the website getting by the limitations of the default viewers, I guess i'm asking if ther is a way to open a pdf on a site, and edit it on that site and then submit the information on that pdf not threw the pdf itself but the site sorta like a typical contact form built in html, but inside the corrtect boxes would be the attached completed pdf file. i guess i'd need to open a a new page inside of a div layer and then submit the information inside the div,, Mainly the complete pdf file, to the mailto: email.
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any help would be greatly appreciated.

You're not going to get that with a PDF form, sorry. A year ago I'd suggest that you look into Adobe's FormsCentral, which allows easy creation and administration of both web and PDF forms, but they have decided to discontinue this service. They have directed customers to similar services such as JotForms, so you might want to look into that.

How can I read a binary file?

In my AIR application, I'm trying to read a binary file and then post it via an HTTPService to a remote ColdFusion component that accepts a "binary" type argument. The result of the post is always:
The FILEOBJ argument passed to the addFile function is not of type binary.
Here is how I'm reading the file in Flex, where fileObj is of type File:
var fs : FileStream = new FileStream();
var bytes : ByteArray = new ByteArray();
fs.open(fileObj, FileMode.READ);
fs.readBytes(bytes, 0, fs.bytesAvailable);
fs.close();
I then pass "bytes" as the parameter to my HTTPService's send call, like so:
var params : Object = {method : "addFile", fileObject : bytes};
service.send(params);
When I debug, bytes contains the correct file size. Is it not in binary form? I've tried several other suggestions, but with the same result, so would appreciate any help.
Thanks!

One more step...
short are U16 integer
double are double precision float
bool seem to be 2 bytes (= U16)
char are string (variable length)
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Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

"Read from Binary File" and efficiency

For the first time I have tried using Read from Binary File on sizable data files, and I'm seeing some real performance problems. To prevent possible data loss, I write data as I receive them from DAQ, 10 times per second. What I write is a 2-D array of double, 1000 data points x 2-4 channels. When reading in the file, I wish I could read it as a 3-D array, all at once. That doesn't seem supported, so I repeatedly do reads of 2-D array, and use a shift register with Build Array to assemble the 3-D array that I really need. But it's incredibly slow! It seems that I can only read a few hundred of these 2-D items per second.
It also occurred to me that the Build Array being used in a shift register to keep adding on to the array, could be a quadratic-time operation depending on how it is implemented. Continually and repeatedly allocating bigger and bigger chunks of memory, and copying the growing array at every step.
So I'm looking for suggestions on how to efficiently store, efficiently read, and efficiently reassemble my data into the 3-D array that I need. Perhaps I could simplify life if I had "write raw data" and "read raw data" operations that write and read only the numbers and no metadata.then I could write the file and read it back in any size chunks I please -- and read it with other programs besides. But I don't see them in the menus.
Suggestions?
Ken
Solved!
Go to Solution.

I quote the detailed help from Read from Binary File:
data type sets the type of data the function uses to read from
the binary file. The function interprets the data starting at the current file
position to be count instances of data type.
If the type is an array, string, or cluster containing an array or string, the
function assumes that each instance of that data type contains size information.
If an instance does not include size information, the function misinterprets the
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So I see how I could write data without any array metadata by turning off "prepend array or string size information", but I don't see any way to read it back in such bare form. If I did, I'd have to tell it how long an array to read, and I don't see where to do that. If I could overcome this, I could indeed read in much larger chunks.
I'll try the auto-indexing tunnel anyway. I didn't tell you the whole truth, the 3-D array is actually further sliced up based on metadata that I carry, and ends up as a 4-D array of "runs". But I can do that after the fact instead of trying to do it with shift registers as I'm reading.
Thanks,
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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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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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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!
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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?
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Certified LabVIEW Architect
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Visa Read Timeout Occurs with multiple Reentrant VI Calls

I have written a test application in Labview (6.1) which will be used to test (burn-in) up to 15 serial instruments through a 16 Port USB->RS232 Hub. Here's how it works:
When the App loads, I am transmitting a Connect command to each of 15 com ports (one-at-a-time) using VISA. If I receive the proper response from the unit on that port, I add the port to an array and continue on to the next system. Once I've found all systems on the hub, I wire my array of active Visa references to a for loop in which I open up to 15 reentrant VIs which will run in the background in parallel. Each of these reentrant VIs (all are idential with the exception of the Visa Resource they use) running in the background are sending commands to the the respective instrument and receiving a response. One Function in particular "Get Unit Status" is important and the response determines whether or not the instrument is functioning correctly. Here's the problem -- In my Main Loop, I am continuously acquiring indicator values from each of the reentrant VIs that are running in the background. After a period of time (not consistent) I will lose communication with a port (the symptom is no response from the unit). I've looked closely at the COMM engine I created and found that the Visa Write function is completing without error, then when I perform a Visa Read I immediately get the "Timeout occured before operation completed" error (please keep in mind that this occurs after 100-5000 successful attempts at writing/reading). Eventually another port will drop out, followed by another. This seems to stop occurring and the remaining systems run to completion without a problem.
Some background on what how I'm setting up my Visa Sessions...
When I originally scan for systems (before I load and run the Reentrant VIs)
- Init Visa Port
- 19200, 8, N, 1
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- Timeout = 400mS (I've tried larger values already) 400mS should be plenty
- Termination Char=13 (/r)
- Open Visa Session
- Visa Write "CONN18/r" (the command required to connect to my instrument)
- Visa Read with 1 for requrested byte count to read 1 byte at-a-time, concatenating the results until /r is received (or 1000mS timeout occurs -- this is not a VISA timeout) I've also tried 16 for requested byte count and just waiting for Visa to timeout -- both methods work.
Once all 16 ports are scanned I Close ALL of the ports using the Visa Close Function.
It is important to know at this time that I "AM" using proper wiring flow to ensure open occurs before write, write occurs before read, etc.
I'm assuming at this time that all of my Visa sessions are closed.
On to the Reentrant VIs:
Inside each reentrant VI I first Initialize all of my variables and Init/Open a 'New'? Visa session using the same parameters mentioned above.
Then I enter the "Run" case structure where all of the communication begins.
I am using the same Communications Engine to operate the instrument as before (the only difference being that all of the VIs in the comm engine are now reentrant and operate at higher priorities) I have actually saved two different versions of the engine (one for the reentrant calls and one for when I first scan for systems from my Main GUI).
When I init the reentrant VI, I am placing the Duplicate Visa Resource output of my Visa Open Function on a shift register. When I enter the Run case, it takes the Resource from the register on the left, wires through any Comm Engine Vis then back out to the shift register on the right and keeps going for a 12-hour period or until "Get Unit Status" has returned 60 naughty results.
On my Main GUI I am continuously (every 500mS) I am Getting certain Indicator Values from each reentrant VI AND I am also setting some control Values on each reentrant VI. There is no VISA interaction between each Reentrant VI, and the Main GUI.
As I said earlier, up to 15 systems will run for a time, then one will stop responding, followed by another, and another until a few remaining systems will run to completion.
Any advice as to why I'm encountering the timeouts with the VISA read fucntion as I have metioned would be appreciated. I managed to find one suggestion which uses the Bytes at Port function to ensure there is data at the port before doing a Read otherwise, skip the read and retry the whole operation -- I haven't tried this yet.
Sorry for the wordiness of my question. If anyone would like some screen shots of portions of my code (I can't submit the actual code because some of it is confidential) I'd be happy to post them.
Doug.

Hi Doug,
The first thing I would recommend is the solution you have already found, to check and see if there is data at the port before attempting a read. I would be interested to see if this will solve the problem. Does there seem to be any trend to which ports have this timeout error? How many ports does it cut down to before operation seems to continue as expected? Does this number vary, or is it always the same number of ports? I think the best thing to do will be to identify constant attributes of how the error is occurring so that we can narrow it down and see what is going on.
John M

Read in Binary form in VISA read function

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