Avi valid reference

An AVI file can created or opened via "IMAQ AVI Create" or "IMAQ AVI Open," respectively. Each of these subVIs produce an AVI File Reference. Is there any way to check if that reference is valid? The "Not a NaN/Path/Ref?" primitive always returns true for this datatype, regardless of whether the AVI file reference refers to a valid open file or not. I have also tried other methods, all unsuccessful:
1) I saw that the AVI file reference is really just a strictly typed datalog file reference (with datatype int32), but trying to typecaste it to a datalog reference and checking that reference for validity did not work.
2) You can typecaste the AVI file ref to an int32 that produces the same number as the probe of the reference, but this number stays the same whether the AVI reference is open or closed, so it does not help
3) I tried to use the "IMAQ AVI Get Info" subVI so that I can trap an error and determine if the reference was valid, but this only works for read sessions of the AVI file reference (i.e., created with "IMAQ AVI Open"). A reference created by "IMAQ AVI Create" is a write session, and cannot be checked this way.
It seems like this should have already been implemented, but I guess LabVIEW treats the AVI file refernce quite uniquely. Many of the primitives that work on references do not work on this datatype. Is there any way to reproduce the functionality of "Not a NaN/Path/Ref?" for an AVI file reference?

I thank you for the idea, but I'm afraid it does not work as I wanted. The attached image shows 3 examples illustrating my point.
In the first example (untitled1), "IMAQ AVI Create" is used, and both probes remain false.
In the second example (untitled2), "IMAQ AVI Open" is used, and both probes remain false.
In the third example (untitled3), "Open\Create\Replace File" is used, and the "Not A Reference" primitive is false for probe1 and true for probe2. Note: if I use the "equal to Not A Ref" method for the third example (like for the first two examples), I get both probes remaining false as well.
I'm looking for a way to replicate the behavior of the third example for AVI file references.
Message Edited by Yuri33 on 07-05-2007 09:59 AM
Attachments:
tmp_aviref_test.PNG ‏43 KB

Similar Messages

Get associated avi file from avi file reference

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Y-intercept calculation problem: "A2:A7" isn't a valid reference

This is actually a problem I have with many calculations in Numbers but I will use the following as an example:
I am trying to calculate the y-intercept and slope for a set of data. Table 1 contains the raw data with each data point in triplicate. In Table 2, column 1 is the ordinate value and column 2 is the abscissa value, which is the average of the triplicates. I would like to place the calculation for the y-intercept in column 3 and the slope in column 4, but always get the error, "A2:A7" isn't a valid reference" for a result. Instead, I have to have a third table for just the y-int and slope. Why isn't A2:A7 a valid reference?

No, I didn't; I only had a 5 rows but I made it 7 rows - so it was a 4 column x 7 row table - and then the formulas worked. The odd thing is that there was still only data in the first 5 rows and, after I set up the formulas, I reduced the table back to 4x7 and the formulas remained unchanged. Thanks for the help.

"Cost" isn't a valid reference ...

I'm new to Numbers - lifelong Excel user/developer.
I'm trying to do something which I beleive should be extremely simple. I have two spreadsheets, one called "Expenses" and one called "Summary." Revenues has three tables.
In the "Summary" spreadsheet, I'm in a table and I'm trying to multiply a cell from the "Fixed Costs" table in "Expenses" by 12 to get the annual fixed costs.
When I type "=" and then use my mouse to select any cell in the "Fixed Costs" table in the "Expenses" spreadsheet, it fails to return a valid reference.
Instead of a valid reference, it just the text "Y1 Cost" ... which generates the error in the subject of this discussion. (See graphic).
All of the other tables in "Expenses" return proper cell references (see below).
I've verified that the cell in question is numeric (its a formula itself).
I've deleted the table and re-created it.
If I try to create a sum (=sum( ... .and then select B2:B3)... it works. But selecting a single cell does not.
Its making me a bit crazy.
I can work around it ... but I'd sure appreciate understanding why its behaving this way, so I can avoid it in the future.

"I have two spreadsheets, one called "Expenses" and one called "Summary." Revenues has three tables."
"Spreadsheet" = "Document"?
Or do you mean "My document has two Sheets, "Expenses" and "Summary"
What is "Revenues"? Another Sheet in the current Document? A separate Document?
Is your profile accurate? It lists Mac OS X v10.4.10, one update before the final one for v10.4. Unlikely to be a contributing factor, but possible.
I don't see a reason for the failure. I would suggest turning off 'Use header cell names as references' while building formulas/tables, but that may just be personal preference on my part.
Regards,
Barry
PS: Answers to the questions may help someone come to an AHA! moment before I get back to this.
B

Validating reference to remote bean

Hi,
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Something myLoggerBean.stillthere(), which lets me create a new one in case someone redeployed the bean.
Any chance of doing that or will I have to stick with my exception handling like:
try{
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Unfortunately we do need to log using such a heavy weight solution. Of course this is not used for all simple log output of the software. We do use Log4J for that, this solution is only for request and response SOAP.
We are creating a life science software which needs to record the webservice requests arriving at our replication. This is so that at a later point in time we can perfectly reconstruct what requests arrived and what responses were send out, in case someone blaims us to have caused harm by wrong results.
Thanks again for answering.
Greets Robbi

htmlb:tableView : (table) Attribute value is not a valid reference

Hi All,
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Kishan

I think DATE_RANGE_PAN is not table. Make sure its a table. If issue persist, post the data type declaration here.
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How to check validity of data reference

Hello everybody,
in my application I use a help class to buffer data objects.
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First I call the method 'METH_CHECK'. As import parameter I pass a reference to my databuffer class.
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Thank you very much,
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Hello Oliver,
Another approach might be to avoid any dependency to the caller at all.
Regards
Klaus
data:
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field-symbols:
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create data buffer_Reference like i_Value.
assign buffer_Reference to <buffer_Data>.
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Can I use a cell value to reference a table on another sheet?

I'm not sure if this is possible and I have had no luck with searches, here is what I am attempting to do...
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For example:
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Cheers

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A File Reference and its evolving life!

Hi all,
I've noticed something that came as a little bit of a surprise to me, but I think I have the explanation, at a hand-wavy higher level anyway. What I have not established is if this is a 'bug' or a 'feature', and if there are any ways the following issue can be avoided at the NI function/api layer.
Consider the file open and file close function. You open a file, you use the reference to the file to write/read data, then at some point you close the reference and the close function spits out the file-path. Here are a couple of tid-bits you may not be aware of (that are easy to test):
Q1) After your application opens/creates a file and starts using the file-reference to make file writes, if an external source changes the file-name of that file... guess what will happen on your next write function call?
A1:: The write successfully updates the newly re-named file with your new data without producing an error or a warning. (At least this is the case if your program is running on a vxWorks cRIO target and the file-name is changed directly on the cRIO via an FTP browser.)
Did this surprise you? It did surprise me! -My handwavy explanation is that the file-pointer is perhaps managed/maintained by the OS, so when the OS tells the file-system to rename that file, the pointer that LabVIEW holds remains valid and the contents of the memory at the pointer location was updated by the OS.
Q2) Continuing from the situation setup in Q1, after writing several new chunks of data to a file now currently named something completely different than when the file reference was originally created, you use the close function to close the file-reference. What do you expect on the file-path output from the close function?? What do you actually get??
A2:: The close function will 'happily' return the ORIGINAL file-name, not the actual file-name it has been successfully writing to(!). This has some potentially significant ramifications on how/what you can use that output for. At this point there is a ton of room for pontifications and more or less 'crazy' schemes for what one could do, but I argue that the bottom line is that your application has at that point completely lost the ability to accurately and securely track your file(s). Yes, you could list a folder and try and 'figure out' if your file-name was re-named during writing and you can in various ways make more or less good 'guesses' on which file you in reality just had open, but you can never really know for sure.
So, what do you guys think?? Is the behavior of returning the (incorrect) original file-path when you close the handle a BUG or a FEATURE?? Would it not be possible for LabVIEW to read back the data contained in the (OS?) pointer location and as needed update the file out path data when it closes a reference? Should we not EXPECT that this would be the behavior?
Q3) Again, continuning from the above situation, lets assume we are back at the state in Q1, writing data to a (re)named file. What happens if the file is deleted by an external process? What happens to the file reference? File function calls using the reference?
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I am not sure if the above is possible on e.g. Windows, Windows would probably prevent you from re-naming a file that has an open file-handle to it, but this is definitley observable on at least vxWorks cRIO targets. (I don't have PharLap ETS or RTLinux devices so I can't test on those targets.. if you want to test its pretty straigth forward to make a simple test app for it.)
[begin rant-mode related to why I found this out and why this behavior BITES]
There are situations where the above situation could cause some rather annoying issues that, for somewhat contrived reasons related to cRIO file API performance, CPU and memory resource management, are non-trivial to work around. for example, using the NI "list folder" to listing folders take a very hefty chunk of time at 100% cpu that you cannot break up, so polling/listing folders after every file update (or even on a less regular interval) is a big challenge, and if you are really unlucky (or didn't know any better) and gave the list command in a folder with 1000's of files (as opposed to less than about 100 files), the list will lock your CPU at 100% for 10's of seconds... Therefore, you might be tempted to maintain your own look-up table of files so that your application can upload/push/transfer and/or delete files as dictated by your application specific conditions... except that only works until some prankster or well-intention person remotes in and starts changing file-names, because then your carefully maintained list of file-names/paths' suddenly fall appart.
[\end rant]
QFang
CLD LabVIEW 7.1 to 2013

Hey guys, thanks for turning out your comments on this thread!
-Deny Access : still able to re-name (and delete) the file via FTP browser (didn't test other file avenues). I think this is for the same reason that NI vxWorks targets (such as cRIO-9014) do not support the concept of different users with different rights, as such, everyone have access rights to everything at the OS level. Another issue for me would be that "Deny Access" does not work on TDMS file references, so even if it worked, it would not help me.
--> I strongly suspect that these things are non-issues or issues that can be properly managed, on the new NI LinuxRT targets since (the ftp is disabled by default) it supports user accounts and user restrictions on files/folders. The controller could simply create the files in a tree where 'nobody else' has write access.
Obviously nobody should mess around with files on a (running) cRIO, but customers don't always do what they are supposed to do.
As far as the 'resources' or overhead to update the file-refnum with the new information, this would not be needed to be done in a polling fashion, simply, when the file-close function is called, as part of that call it updates its internal register from the pointer data, so this should be a low overhead operation I would think? If that is a true concern, a boolean input defaulting to not updating or a separate 'advanced close' could be created?
I've included a zip with the LV2013 project and test VI's (one for tdms one for binary) that I've used. nothing fancy, but in the interest of full disclosure. The snippet is the 'binary file' test vi, in case you just want a quick peak:
Steve Bird's findings of (yet) another behavior on Pharlap systems is also very interesting, I think!!
[EDIT] JUST TO CLARIFY, on vxWorks, the re-named file keeps being successfully written to, unlike the PharLaps' empty file that Steve Bird found.
QFang
CLD LabVIEW 7.1 to 2013
Attachments:
cRIO Tests.7z ‏30 KB

How can I dynamically reference a sheet based upon the contents of a cell

I'm using Numbers to store specifications for various products. Each sheet stores specifications in a standard manner (i.e. same table and cell names) and the sheet is named according to the name of the product.
On another sheet I've got a dropdown list containing the names of the product tabs. I'd like to dynamically pull data for a particular product when it's sheet is selected in the dropdown list by using the dropdown cell in a reference like:
=B1::STC::A4, where B1 is the dropdown list and STC::A4 is the product specification table and cell reference.
When I use this, the B1 reference fails.
Any suggestions would be greatly appreciated.
Thanks.

Amos,
you will have to use the indirect function to convert the string you are creating into a valid reference.
Note: The Sheet names, Table names and cell references must all match exacty.
If the sheets are named "B1", "C1" and "D1" and the popup menu is in the cell A1 and contains the strings:
B1
C1
D1
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then you can create a valid reference like this:
= indirect(A1&"::STC::A4")
if the table name were also dynamic and were stored in cell A2 you could create the reference like this:
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Event applied to control references

Hello!
I built a VI that can run on its own or controlled by a superordinated VI. If there are valid references comming into the subordinated Vi these are used exclusivly, otherwise references to the controls of the superordinated VI are used.
So inside my program I exclusivly use references and property nodes to access or change data.
My first question is if you think that is a bad solution concerning the performance of the VI and if you have any improvements?
The next problem is that my VI is quit slow now (there is a while loop checking all the time if there are changes made to the controls (via their references) and acquiring data (using RS232) and updating controls. Thereby I use a 20 frames long sequence inside the loop.
Is that the reason for slow performence?
To speed things up I considered to us an event structure instead of the sequence to check the changes and only to do the acquisition every cycle.
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Alexandra

> But I don't see a possibility to use the event structure to check
> events on value changes of controls via their references.
>
With LV7, it is possible to use an event structure on control references
to another panel. As for whether this is the reason for performance
problems, that is hard to say without seeing your application.
First suggestion is to use the profiler. Tools>Advancec>Profile VIs.
It should help you start looking in the right place and run informed
experiments.
Another way of doing this is to send it to [email protected] and let me use it
as part of the VI critique going on at NIWeek. We will keep the names
anonymous and find the best technique we can for the problem you are
trying to solve. This offer goes for anyone with a VI t
hat they'd like
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Weak References in Listener Lists

I've found a common source of memory leaks is when objects that add themselves to listener lists forget to remove themselves when they are done.
It would be nice to generalize and say that listener lists should contain weak references, but there are probably valid cases where a listener's only valid reference is through the listener list.
It would be nice to extend the listener pattern so that the listener could specify if they should be referenced weakly, for examplemodel.addChangeListener(this, true)where true indicates the reference to the listener should be weak.
In some cases like the Model View Controller pattern, it probably makes sense that whenever a view listens to a model it should be weakly referenced. For example, when you construct a JTable and pass the model as a parameter to the constructor, the JTable should always specify a weak reference when it listens to the model.
I think supporting a feature like this in the listener APIs could help reduce the potential for memory leaks and make code a little more maintainable.

There was another time that I dabbled in this idea.
But it always comes back to objects cleaning up
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If you have to write a clean up method, it kind of defeats the value of having automatic garbage collection to a degree. I like to be able to let my Objects just fall out of scope or just become unreachable when they are no longer needed without having to actively manage their deallocation.

Reference loss when created by Dynamic VI

Hello,
I am actualy designing a program using a Model-View-Presenter Template.
Views and presenters are contretized by dynamic lauched Vis.
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Main models are instantiated by the main presenter. Others models, that might belong to main models can be instantiated by sub presenter within sub presenter thread.
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Does anybody ever met this situation?
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thanx for answer.
Pierre

And reference creation goes that way :
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Reference book

Dear abapers!!
Need your advice!!
im planning to take up sap certified development associate (c_taw12_731) certification test so i was wondering whether a previous version reference book is valid to use??
i have 2+ years of ABAP development experience.
im on a saudi arabian residence visa so i can take the test exclusively without training thats confirmed from SAP middleeast.
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taw12_1, taw12_2.
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Best Regards.

Hi,
You can check the material that is covered at the SAP Training website:
https://training.sap.com/shop/certification/c_taw12_731-sap-certified-development-associate---abap-with-sap-netweaver-73…
ABAP doesn't change much over time, so all the study material you can find will help you prepare.
Try to find as many (realistic) sample questions as you can. They are very good at helping you study
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An invalid or empty reference to a Cascading Style Sheet file was specified.

Hello,
I am having an issue with a page layout that I created yesterday and that was running just fine before I left work. I shut down my environment and system at the end of the day. When I came in today and fired up SharePoint 2013 and SPD 2013, I
noticed that when I attempted to open the Page-Layout I worked on yesterday I received this message:
An invalid or empty reference to a Cascading Style Sheet file was specified. Valid references must specify only a filename that ends with a ".css"
I have validated both the master page and the page-layout for malformed or incorrect css references but there are none.
This kind of stuff drives me crazy with SP. So much time spent chasing needles and the error message might have nothing to do with the real cause.
Thank you for any and all help you can provide.
Tim

Hi Tim,
Could you please reproduce the steps of creating the page layout today, and see if shutting down your environment and system affects something which might cause the issue?
In addition, please check in ULS log per the issue timestamp and see if there is more error information can be help to find out the root cause.
Regards,
Rebecca Tu
TechNet Community Support
Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact
[email protected]

Avi valid reference

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