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Publisher subscriber example

August 14, 2020, 4:58 am
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I'm currently working on an application that comprises multiple VIs running in parallel but need to exchange data and I'm trying to find the best method for data sharing. The one most recommended design after perusing these forums has been to set up a publisher subscriber implementation. I've searched for a simple example to no avail.  This one I found in the LAVA forum did not include the actual file.   https://lavag.org/topic/13598-labview-programming-structures/

 

A simple example is much preferable as I'm currently not well versed in labview OOP. Any help will be appreciated. Thanks in advance.

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re-download examples

August 14, 2020, 5:42 am
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Hello

 

I accidentially deleted the example 'Continuous Serial Write and Read.vi' which is located in folder 'C:\Program Files\National Instruments\LabVIEW 2013\examples\Instrument IO\Serial'

 

I think that this example gets installed when one installs the Visa libraries. 

 

How can I find the example and download it again?

 

Thank you.

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How to apply same change to all remaining cases of a case structure?

August 14, 2020, 6:46 am
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Hello everybody. I would like to consider the following scenario.

 

I have a Case Structure and I have already defined e.g. 100 cases. Now I want to add another object, e.g. a Control Object. How can I avoid to copy-paste this in all cases and just perform this kind of change in one case and make such a change valid for all remaining cases?

 

Thanks in advance for your help 🙂

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puchasing and upgrading LabVIEW

August 14, 2020, 7:46 am
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I just need some advice / looking for opinions. 

I was just hired at a new company, partly for my LabVIEW experience.

My boss has the LV 2014 SP1 full development version, and has the application builder add on.  

He would like to upgrade his version to the Professional Development system and buy the professional development system for me.

 

The issue is, he would like to do both with two different quotes, each under $5000.  Over 5k requires a ROI calculation, which is 'difficult and time consuming to get approved'.

 

Does NI run any specials on the Pro version that would put it under $5000?

 

Does it make sense that he would want to upgrade when he already has the application builder toolkit?

 

Thanks.

 

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Time Delay missing after I upgraded

August 14, 2020, 7:54 am
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I just updated my LabVIEW from 2017 to 2020 (32bit only).  When opening my project and main vi, I am missing all my Time Delays and have to go in and manually place them.  Is this a bug or is there something in the install that I didn't do correctly?

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Queue not queueing

August 14, 2020, 8:16 am
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I have a VI that I am trying to use what I believe is a Producer-Consumer QSM architecture.  It isn't working.  I have disabled the consumer loop and I never see any elements in the queue.  What am I missing?  I know that there is data in the 2D array because I am displaying it on the front panel (as in the motor speed indicator in the pic.).  The save button is pressed.

Queue.PNG

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NI 9205 w/ DSUB differential AI greyed out

August 14, 2020, 9:50 am
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Hello,

 

I am using a NI 9205 w/DSUB module on a cDAQ 9188 chassis. The documentation online says that the 9205 should support 16 channel differential input but when I open DAQmx in labview to setup the channels, the differential option in terminal configurations is greyed out.

 

Is there any additional configuration that needs to be done to enable the option ?

 

Any help much appreciated.

 

Thanks

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error 85; Scan From String (arg 1)

August 14, 2020, 10:21 am
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the background is that: I am developing a vi to control signal generator and power amplifier to get the power that I need. It's like making a+b=c. C is the power I need at different frequencies, a is the output of sig gen, and b is the gain of amplifier.

 

The vi will adjust the a and b under certain ranges until it finds suitable a and b (while loop). Then it will move forward until all the frequencies are done (for loop).

 

The sig gen and amplifier are initialized at the beginning the for loop, and closed at the end of the for loop, which means that during the entire program they will open and close one time each.

 

It works fine with certain c set and all instruments shut down after finishing, but somehow once it stops at some point and reports that:

 

"error 85; Scan From String (arg 1) in AR Amplifier.lvlib:AR Amp.lvclass:Read Fault.vi."

 

The error message was captured by the close.vi. I commend it to shut down the power before close.vi, but in reality, the amplifier which reports fault keeps running and the sig gen which works fine shuts down normally, which means that the error bypasses my command.

 

Capture.PNG

 

here I upload a simplified version of my vi for us to discuss. 

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Custom UI Palette in LabVIEW NXG 5.0 Using HTML placeholder

August 14, 2020, 10:41 am
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LabVIEW Created DLL's Application Space

August 14, 2020, 11:23 am
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I'm curious how LabVIEW handles multiple DLL's and their application space in certain scenarios when those DLL's are built in LabVIEW.

 

Background: We use a PPL based HAL architecture for work. This has been great for LabVIEW and TestStand based applications. I've been tasked with exploring what it would take to make our HAL work with other code languages. Basically the idea is to create a wrapper over the HAL and build a *.dll out of it. Simple enough. That part I have got working. For each instrument PPL, I have a respective instrument DLL and can call into it and use it. Everything would work the exact same if I created one monlithic DLL that encompassed all instruments, but since I make individual ones it get's a little more complicated.

 

My question is how LabVIEW handles the application space for all of these dll's. Do they share one big one, or does each dll create it's own space. In turn meaning even if they are referenced in the same application, they are not sharing the PPL's themselves.

 

Things I have noticed: Using TestStand, calling into the PPL's and using the DLL's that are wrappers for those same PPL's, the application spaces are different. This makes TestStand launch two runtime engine instances for the LabVIEW PPL and the LabVIEW DLL. When using Multiple DLL's, that reference the same PPL's they also don't share the application space, since shift registers don't work.

 

So simple enough, does each LabVIEW DLL launch it's own instance of the runtime engine, even if there are multiple LabVIEW DLL's in the same application (Whether that be c#, c++, c, etc...).

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Error Message - In Place Element

August 14, 2020, 12:15 pm
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LV 2018 SP1, Win 7

 

Occasionally, I get this message when my program terminates, usually after something goes wrong.

Err Msg.PNG

 

Pressing OK or closing the box just makes it come back after a half second or so.

The only way out is Ctl Alt Del.

It doesn't tell me anything useful - it's a noun without a verb. 

I assume it's an error of some sort.

Does it mean that a particular IPE is still waiting to complete, and my DVR (Data Value Ref) is trying to dispose?

 

Any ideas?

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Uninstall LabVIEW without uninstalling all my compiled applications

August 14, 2020, 12:45 pm
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Since NI inflicted the NI-Package manager on us life has not been good.

 

I can't upgrade my main development ATE station to to LabVIEW 2020 because Ni Package manager cant uninstall some older version of something or other. (It doesn't say exactly what the problem is, just that it can't uninstall package 67b28cdf-799f-blah-blah-blah)

 

So I decided, fine I will manually uninstall LabVIEW 2019 and start "clean".

 

But the Ni-Package manager will not uninstall LabVIEW 2019 unless I also allow it to uninstall every single COMPILED LabVIEW application on the computer!

 

Why do I have to uninstall every compiled executable when I uninstall the LabVIEW development environment? 

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Read from text file and convert to numeric 1d array

August 15, 2020, 4:35 am
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I looked around a lot of documentation and found out either some of them outdated or simply lack of information. 

Here is a sample text file that I want to convert to 1d array. Any help?

LabView 2020

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Read email in labview

August 15, 2020, 4:54 am
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Hello. I am trying to read email in labview. I want to build a vi that can read the title and the body and make me albe to extract them as strings. Any ideas or examples will be helpful. Thank you!

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Problem installing DSC Labview 2019

August 15, 2020, 10:48 am
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Hello, I am trying to install DSC from NI Package Manager but when installing SQL Server 2008 R2 Express Edition the error of image 1 appears. I also tried to install it by VI Package Manager (XDSC Components) and the error of image 2 appears. I have Windows 7 and LabView 2019. Thanks in advance.

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Why might my myRIO read non-1kHz analog signal amplitudes incorrectly?

August 15, 2020, 5:45 pm
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Hello,

 

I am trying to read an analog waveform created through DDS by an external DS04102C oscilloscope on myRIO. However, I find that the analog signal reads the incorrect voltage if the signal is at a frequency that is not 1kHz. Does anyone here know why that may be?

 

For instance, I can generate a 1V, 1kHz signal, then read a 1V, 1kHz signal. But if I change the 1kHz to 2kHz, for example, the measured voltage decreases.

 

I have attached my project below. The project uses the FPGA Target, "FPGA_AnalogReader", and the RT Host, "AnalogSignal_Reader". The FPGA code reads an analog value in the ConnectorC/AI0, then it outputs it to a FIFO to be read in the RT. I have been using a Case Selector to move between methods of timing as I am still learning how to sample Analog. On the RT, I keep the Case Selector on True, then use a value of 6000000 for "A Ticks to wait". The "A" refers to analog. The RT also has a disabled section (commented out) that would be used for Digital sampling.

 

The RT does scaling of (RawData * 20) / 4096 to convert the raw data value to a voltage.

 

Let me know if the attached zip folder doesn't work.

 

- Thank you

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Press Push Button if time Elapsed

August 16, 2020, 4:31 am
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Hello,

I am pushing a push button when I want to start my process, and then when I have pushed it I want to start counting 2 sec and repress the button to stop.

Do I need to create another while loop and to have the motor control outside??

Alexis_Koul_1-1597577452890.png

 

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Application crash by msado15.dll used by database toolkit

August 16, 2020, 6:13 am
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I have a labview built application that runs continuously, doing periodic queries on a sql server database. I use the NI database toolkit for this. Recently I started noticing the application "vanishes". I opened the Windows evenviewer (eventvwr.msc) to find the following two errors:

 

1.
Application: GD6.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: exception code c0000005, exception address 67B2E409

 

2.
Faulting application name: GD6.exe, version: 6.3.8.1894, time stamp: 0x5ba06ff4
Faulting module name: msado15.dll, version: 10.0.18362.900, time stamp: 0x6437670b
Exception code: 0xc0000005
Fault offset: 0x0005e409
Faulting process id: 0x257c
Faulting application start time: 0x01d672fb1562e54f
Faulting application path: C:\Program Files (x86)\Gotcha Data\GD6.exe
Faulting module path: C:\Program Files (x86)\Common Files\System\ado\msado15.dll
Report Id: e351597d-a4bf-4d8a-a2e9-5fdbf62208ea
Faulting package full name:
Faulting package-relative application ID:

 

It has happened a couple of times now. I can deal with normal Labview errors, but I can't deal with errors that simply kill the whole application process. I found nothing on this website mentioning this DLL, although it is evidently a core library being used by the database toolkit.

Any suggestions how I can debug this?

An alternative connection method or other toolkit would also be a possible solution.

 

I did add a query recently to the application. This query runs many times before any one crash, but I did not experience any crashes before I started using that query.

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XML format issue

August 16, 2020, 8:22 am
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Hi team , 

 

I am writing the array data  content as xml file . 

 

In the XML file , test parameters name also ( Caption )   i need to Write  . 

 

I gave as 1d array as output  , so all caption / Parameters are all listed as " Status " .

 

But  parameter name  i need to write first ,  after that  i need to write the parameter value in the file 

 

For eg :

Parameter name  : Testcase name

Parameter value  : Voltage Test 

 

Parameter Name : Higher limit Value

Parameter  value  :  5

 

Attached the screenshot of xml file and Test vi . 

 

Please advise and suggest 

 

Thanks in advance 

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Format XML data

August 16, 2020, 9:05 am
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Hi team , 

 

I wrote a data into XML file , but format was i need to change 

 

All data are written in a single line .  All parameters name and data need to write in separate new line 

 

How i need to modify and write. 

 

Please suggest 

 

Thanks in advance 

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