FFT in CVI

Hello CVI user,
I use the FFT function in CVI, sometimes
the FFT calculates every second "Q" value as "not a Number" (NaN)
e.g. I can verify this behaviour if I feed the FFT with constant zeros for
I and Q.
Normally the result should also be also zero's.
The problem occurs not every FFT call and the FFT returns no Error
(both Arrays are defined as double- N = 1024)
Could this be an NT problem? With W98 it seems to work
Thanks
Klaus

> I think you confirmed what I had suspected: that LV and CVI
> basically just act as C compilers. I was worried whether the nice
> graphical front-end slowed down computation, when compared with a
> simple compiled C program.
As stated in the other posting, the FFT and other analysis libraries are
shared between LV and CVI, and can in fact be called from other
environments capable of calling a DLL.
But, just to make sure you don't jump to the wrong conclusion, CVI is a
C compiler, an ANSI compliant compiler. LV is not a C compiler, but a
compiler of the G language, the graphical dataflow diagrams in LV. As
with other languages, some of the functionality will come from code
being generated, and other by linking to OS libraries or
NI shared
libraries.
Greg McKaskle

Similar Messages

NI-4552 w/2 FFTs and 2 Analog channels?

I am trying to use the DSA library with VB6 to capture two FFTs (channels 0 and 1) while still capturing raw audio on channels 2 and 3. Is this possible? If so, can someone clarify the steps to do this, or point me toward one of the examples that shows something like this? Thank you for any input.

It is possible for NIDSA to return 2 FFT's (ACH0 and ACH1) and 2 Time domain data (ACH2 and ACH3).
I would first like to make sure you are using NIDSA 1.2 - Could you please confirm you're using this version of NIDSA ?
The reason for this question is that we've been adding new examples for VB users as well as a Software user manual that should help you getting started with your 4552
http://digital.ni.com/manuals.nsf/websearch/032430F78301D4A986256AC7004DFC52?OpenDocument&node=132100_US
Anyway, the steps to achieve what you're looking for :
- Initialize NIDSA
- Configure Mode as FFT_4_Channels
- Configure HW parameters (range, trigger, etc...)
- Route ACH"i" to analyzer"i" [i=0 to 3]
- Configure baseband FFT settings (span, averaging
mode) [Note : sampling frequency will be calculated from the span you define)
- Check if new measurement is available (in a loop)
- If new measurement is ready, Read Base_FFT0, Read Base_FFT1, Time2 and Time3
You have additional functions to set units and get useful information such as sampling frequency.
There is also a "Capture" mode you could use in order to save time records to file.
I attach an example in C that describes the basic steps to use NIDSA.
It's been developped using LabWindows/CVI and it should be quite easy to port it to VB and adapt it to your needs.
I hope this will help !
Gerald Albertini
Attachments:
4552_4_Chan.c ‏15 KB

FFT(mag phase) and sample count

I am using the FFT(mag and Phase) VI in version 6.1. When the sample count sent to the fft vi is increased the magnitudes decrease. What is causing this? Does the VI divide by the sample count?
In advance, thank you!

The resolution of FFT depends on the sampling rate as well as the number of samples used to compute FFT (Fs/N). When you reduce the number of samples, the resolution of FFT comes down. This means that the peak that you detected prevously might have gone undetected.
Kallis
Have a nice day!!!
LabVIEW | LabWindows/CVI | TestStand
Certified LabVIEW Architect

MyRIO FPGA FFT Express VI timing analysis for multiple input mode - trying to perform fft's on a 3-axis accelerometer

Hi Everyone!
Project Background:
I've been working with the myRIO FPGA in an attempt to generate an application capable of sampling a tri-axis accelerometer and performing an fft on each axis. I've successfully developed an application for a single axis, but attempting to duplicate the code to sample the second and third axes in parallel results in an estimated 150% resource utilization for the tiny FPGA's LUT's. Additionally, I'm looking to avoid sequentially processing each accelerometer input using triggers and a single fft block because that reduces my fft update frequency significantly (e.g. I can't calculate another fft for input 1 until I calculate an fft for inputs 2 and 3).
After reading up on the fft vi, I'm thinking that I can use the M-interval input indexes / Continuous output indexes Input/Output Index Pattern mode. My thought is that I can edit the vi to remove any math that "recombines" these three vectors into a single fft, resulting in 3 separate fft's. I'm also hoping that this process requires less time than using the sequential method described above.
The Questions:
1. Has anyone done an fft on three inputs using the myRIO at sampling rates > 20kHz and fft sizes of 1024 or larger? If so, I may just be lacking some proper resource management.
2. Does anyone know where to find timing information on the M-interval input indexes / Continuous output indexes Input/Output Index Pattern mode? The manual only provides timing diagrams for singel channel / single input modes. I don't want to waste my time modifying the vi if it will still take 3x as long (assuming modifying the vi is even a possibility).
Further Information:
I already have an application written that samples the accelerometers at >20kHz and then performs the fft on the main processor, but now I'm looking to see if it is possible to perform all signal processing on the FPGA side. The processor performs decently enough, but the timing is not as consistent as I would like it to be. Lastly, I am aware that the myRIO itself has a built in accelerometer, but I need to mount the accelerometer in an environment where the myRIO would probably be damaged and definitely cannot fit.
Any thoughts are much appreciated! The excessive FPGA compile times for this thing make the old guess and check method less appealing.
-Chris

Hi Chris,
Thanks for posting and the detailed background on the project! To answer some of your questions:
1. The FFT Express VI does use a significant amount of space. The FPGA on the myRIO is somewhat limited space-wise. Your best option may to implement the FFT for 1 channel on the FPGA and the other two on the RT side.
2. I converted the FFT Express VI to a subVI and I am not sure if you can trim too much code from it. The subVI is also very complex so re-working it would be a significant amount of work. I could not find much documentation on M-interval input indexes / Continuous output indexes Input/Output Index Pattern mode timing.
I hope that this helps!
Thanks,
Frank
Application Engineer
National Instruments

Cannot display square root symbol in cvi

I don't understand why this would be an issue, but if I'm writing in the source window (with the default font of NIEditor), I cannot display a square root symbol "√" - every time I type alt+251, I get "v". Ok, not a huge deal in the source window, but it is a big deal if THAT is what's being stored in a string variable I'm writing out to a file. Additionally, if I use the following to format a string:
"Fmt(setpointUOM, "%s<W%cT/P3", 251);", then setpointUOM = "WüT/P3". If I display this variable in a string control, it displays as "W√T/P3", which is correct, but if I use it in a Text Box or save it to a sql database, it displays "WüT/P3" which is unacceptable.
I've tried changing the fonts but nothing works or I get even stranger results. I've been dealing with/ignoring this since CVI7 and I'm currently at CVI10. Thanks for any help.
Solved!
Go to Solution.

The difference in the display between W√T/P3 and WüT/P3 has to do with the character set that you select for the UI control. From what I can tell, only the OEM code pages map the √ symbol to character 251, so if you want to see √ for that character, you should pick the OEM character set, in that control.
Entering √ with the keyboard in a CVI window seems like a much more problematic task. When you type Alt+251 on a CVI window, the keyboard driver is converting the 251 to 118 (the letter v). I don't know why it does that, but I noticed that the code that it converts 251 to varies, depending on your input language (which you can change in Control Panel>>Region and Language>>Change keyboards or other input methods). When english is selected in the language bar, it converts it to 118. With other languages, it converts it to other codes. I tried entering the unicode value for √ directly, which is Alt+221A (to enter unicode characters using the keypad, you have to follow the steps described here). But it didn't work. It still converted it to 118. I suspect the keyboard driver is doing this because it tries to map 221A to some symbol that is valid in the code page that corresponds to the input language, isn't able to, and picks what it thinks is the closest match.
In lots of other applications (but not all) you can type Alt+251 or Alt+221A and it works just fine. This is because those applications accept unicode characters directly. Unfortunately, CVI isn't one of them. It uses code pages (a.k.a. character sets, or multibyte sequences) instead of unicode, and symbols don't have a universal meaning; they depend on the code page.
Even if all this were not an impediment, you'd still run into the problem that in CVI 2010 you cannot change the font of the CVI source window to use an OEM character set. So, you'd still see it displayed as a v or a ü. In CVI 2012 you can change the change it, and so if you were using CVI 2012 you could conceivably use the clipboard to paste the √, but there is a bug in CVI that is preventing OEM characters from being pasted correctly (I realize the description says that it affects tree tooltips, but it's also generally affecting clipboard operations of some less commonly used character sets).
So, to make a long story short, I think you should continue entering the code directly with the Fmt function, at least until this bug is fixed. And make sure that all UI controls that need to display this string are using the OEM character set.
Luis

Using Excel with Visual C++ 6.0 (need a graph control that behaves as much like the one in CVI as possible)

I hate to beat this to death but I was unable to find a
clear answer to this question. Does NI provide Excel control from within
Visual C++ 6.0?
I read that NI supports the ANSI-C library only for Visual C++ 6.0 users:
Thread : "Re: Benifits of using measurment
studio for VC++ 6.0?"
NI REP : drohacek
Quote : "we made the decision to support Visual
C++ 6.0 users only through the ANSI-C interface and not through the Measurement
Studio MFC-based class libraries."
If there is a suggested way of controlling Excel from within Measurement Studio
for Visual C++ 6.0 then I’d love to know it.
If not, can a plain statement be made basically stating that if you want
to control Excel you can’t use a Visual C++ 6.0 environment even with Measurement
Studio support?
With .NET of course you can just decide to have Excel support added during
project creation. CVI can act as an ActiveX server and easily control
Excel just by building off the examples shipped with CVI. I see that
there is support, using the Measurement Studio for Visual C++ 6.0 Project Wizard,
for taking existing CVI projects and converting them to Visual C++ 6.0 projects
or for calling CVI libraries from a .dll from within Visual C++ 6.0. I suppose I could do the work
in CVI and then convert the project but I'm so deeply tied into all my MFC calls that I don't see
how I can cleanly include the CVI libraries into my existing VC++ 6.0 projects.
What I'm really after here is a visual graph control like the one in CVI that I
can use from Visual C++ 6.0. I purchased a 3rd party graph control for use
in VC++ 6.0 that works well but isn't really visual. I mean you can't
enter any values in it until you run the program and fill it out programmatically.
Then you can see which columns are two narrow, quit the program, adjust the
column width of your now empty control, and repeat, until you get the thing
looking the way you want. If I could call into Excel from within Visual
C++ 6.0 the way I do from within .NET
then I could use Excel to hold the table and just read in the values into my table
control at run time. Basically I'd use Excel as a visual development tool
for all my tables.
I do all my coding from within CVI and Measurement Studio for Visual C++
6.0. I'd use CVI for everything if I didn't depend so heavily on certain
outside controlled C++ .dll's. Could you please suggest then what I can
do to get Excel support for Visual C++ 6.0?
Last question :
Is there any plan to ever have a NI table control like the CVI table control for
use in Visual Studio? One that you can
completely set up before you do any compiling?
I imagine that the way Microsoft sets up their environment makes this idea impossible. Otherwise someone would
have come up with a truly “visual” table control before now.
Thanks,
Grant
Grant M. Johnson
Project Engineer
LECO Corporation

Hello Grant
You can most certainly use Excel with VC++ 6.0. Measurement Studio won't provided you with any classes to talk to Excel in VC++ 6.0. This is because Excel allows control via Automation and you can use its automation API to do anything you need with Excel. This is what CVI uses as well.
You can see this MSDN article on how to set this up. This mentions VC.NET, but it should work the same way.
Here is one that talks about VC 6.0 and Excel.
Here is a code project article about this.
Even with .NET, you have to do thru the Excel Automation support. Excel started shipping with Primary Interop Assemblies (PIA) which are .NET wrappers about the Excel Automation object model. C++ Automation is definetely not as nice as .NET, BTW
See this document for more information about the Excel object model.
I would not recommend using the CVI Excel libraries if all you want to use them for is Excel automation. You will end up creating un-necessary dependencies and go through extra layers that way. You can make calls straight to Excel from VC++ without requiring CVI.
One quick observation about your excel approach. If you decide to use Excel as your table, you might be requiring everyone who uses your application to have Excel installed on their machines. Just wanted to make sure this was acceptable to you.
Have you looked at the Datagrid Activex control, which is one of the common controls that ships with Visual Studio? You can add it to Visual Studio by right-clicking and picking it from the list of installed activex control. If you have not already, you should check it out.
Microsoft has made significant improvements in the number of controls they provide with .NET. They have a Datagrid control that seems to be what you need.
Measurement Studio did add some high level classes for Excel and Word Automation that simplify some common tasks, but these exists for VS 2003 C++ and VS 2005 C++, not for VC 6.0. Underneath, we end up using the same Excel automation classes, so you can easily setup something similar for VC 6.0. Plus you can find alot of references online on how to use the Excel Automation object model with C++.
We currently have no plans in Measurement Studio to create a table control unfortunately. I am assuming when you said graph, you actually meant table, since Measurement Studio already provides a ActiveX graph controls for VC++ 6.0 that is very similar to the CVI graph.
On a side note, VC++ 6.0 is really really old. Have you considered upgrading?
To summarize
- Yes, you can use Excel with Vc++ 6.0 without mstudio.
- Try using the Datagrid Activex control if you just need a table.
- Measurement Studio provides high-level excel and word classes for VC++ 6.0
- Measurement Studio provides a graph control for VC++ 6.0 which is very similar to the CVI graph.
- Measuremnt Studio does not have a table control.
- VC++ 6.0 is really really old. Have you considered upgrading?
Bilal Durrani
NI

Visual Studio or LabWindows/CVI?

I have a bit of a dilemma.
I currently own Visual Studio 2010, IMAQ Vision Development Module 2013, and Measurement Studio (not sure of version). I currently do all of my programming in VB.net. Because IMAQ VDM is stuck in .Net framework 3.5 and there will be no further .net development by NI, I need to plan for the future. My applications need run on Win 8, 9, 43, or whatever my company decides to migrate to from Win 7.
My understanding is that the NI modules I currently own will work with LabWindows/CVI. Correct? I also believe I can use them with C++ using the VS IDE. Is this also correct?
Within my applications I do a lot of interfacing with Excel, writing text files, and interfacing to non-NI devices (cameras, DAQs, scanners, etc). I am able to do these things pretty easily using VB.net using vendor-provided SDK's.
Therefore, my question is this...given the investment I have in software already, do I gain anything by migrating to LabWindows/CVI? What do I lose?
I should point out that regardless of the path I choose I will need to bone up on my programming skills in the corresponding language.
Thanks for all your help!

Hello Steverino!
Here are some advantages when using LabWindows/CVI over Visual Studio, which make the product more suitable for various industry-related applications:
You are correct, LabWindows/CVI integrates with the NI platform: NI hardware and software, like TestStand or LabVIEW (e.g. debugging source code from one software to another, seamlessly).
NI hardware and third-party hardware connectivity.
OpenMP support.
CVI integrates with intrument control.
CVI Run-Time benefits from User Protection.
Run-Time checking (e.g. for uninitialized variables).
Scientific User Interface Controls and GUI Editor.
Advanced debugging capabilities:
Remote debugging support from ADE.
Real-Time debugging support from ADE.
Memory leak detection using the LabWindows/CVI Resource Tracking Window.
Just-In-Time debugging.
Deployment: build custom installers and patches that you can ship as stand-alone easy-to-use installers.
LabWindows/CVI libraries: Advanced Analysis, Toolbox, Connectivity (Network Variables, Network Streams, DataSocket), etc.
Support for LabWindows/CVI Toolkits: SQL Toolkit, Vision, PID, RT.
Regards,
- Johannes.

How can I create an application in MSVC 6.0 to access my FieldPoint modules with CVI 5.0 libraries?

I have an application in CVI 5.0 that works. I am trying to export that so I can develop in MSVC. I need none of the UI provided in CVI, all I need are the simple FieldPoint commands provided in FieldPoint.obj. I have been stumped on this for weeks. I would write my own OPC client but the interface isn't even documented on what commands I would send if I did have an interface. I would prefer just to use the CVI libraries in MSVC 6.0. When I call the FP_Open function the program crashes with an RtlSizeHeap error.
Thanks,
Chad

In theory, creating a dll that encapsulates the FieldPoint functions should work in MSVC. However, National Instruments has not tested MSVC interface, nor have we publicized that this type of setup will work, therefore making support unavailable. The other reason for why we do not offer support of FieldPoint in MSVC is that we have not seen a demand for such an interface. Therefore, I recommend that you create an OPC Client that communicates with the FieldPoint OPC Server. One example of such an OPC Client in MSVC is to use Datasockets, found in ComponentWorks++. You can find this example at the following web site:
http://zone.ni.com/devzone/devzoneweb.nsf/opendoc?openagent&8FEAB5F73CFB68278625683A000B06ED&cat=7CDA3E51FEFC4AA2862568B80071A1E2
If you are using the
serial network module (FP-1000/1001), you can communicate with the FieldPoint modules using the Optomux protocol. For a complete listing of the Optomux commands refer to the FP-1000/1001 Programer Reference Manual located at the following web site:
http://digital.ni.com/manuals.nsf/caba5d53e9b015a186256793004eebb7/bf97516ca18eee728625665e0063594e?OpenDocument
Best Regards,
JohnM

How do I perform an FFT or ReFFT in VB6 using measurement studio

I am trying to make a filter by taking a 1D array of voltages and doing a ReFFT() and padding the high frequencies in the array with a value of zero and then going back to time domain with ReInvFFT(). Here is my code which does not seem to be filtering any high frequency content.
lngReturn = frmMain.CWAI1.AcquireData(varData, varBinaryCodes)
frmMain.CWDSP1.ReFFT varData, realdata, imgdata
For i = (UBound(realdata) / 100) To UBound(realdata)
realdata(i) = 0
imgdata(i) = 0
Next
frmMain.CWDSP1.ReInvFFT realdata, imgdata, varData
After the function is done varData has a 1D array of filtered real voltage values. It does not seem to be filtering and I get back exactly what I pass in. I know it must be something simple that I am missing perhaps the variable cannot be used to pass in and then back out the values??
Please shed some light as there are NO examples of this use of FFT.
Thanks

Arthur,
Thank you for your reply. But at this point, one of my points of confusion is what software I have available to me. I wish I had a useful central help desk to call up and just say, "Hey, load me up with all of the professional version(s) of Visual
Studio. But I do not know what we have license to. And I kind of need to know what the options are, so that I can ask a specific question of our vast buracracy.
For now, I have downloaded only free versions of Visual Studio client software. Since my company does have servers running Microsoft SQL Server, I am going to assume that we have proper licensing for those servers. But does that server license
allow me to get any professional versions of the PC client software for the various Visual Studio(s) 2012?
And if I get a professional version of Visual Studio 2012, does that do away with the three different flavors that I have right now? I have 2012 versions of SQL Server Management Studio, Visual Studio Express, and Visual Studio Shell (Integrated).
Your feedback is much appreciated.
Thanks!

Software Development Engineer positions at Hysitron, Inc. in Minneapolis (LabWindows CVI exp preferred)

Software Development Engineer
Hysitron, Inc. is a premier scientific instrument manufacturer. Founded in 1992 with headquarters located in Eden Prairie, MN we are committed to promoting nanotechnology by developing advanced transducer and control technology. This leadership has made Hysitron the world leader in nanomechanical test instruments. The TriboIndenter®, TriboScope®, Ubi, and other Hysitron innovations have opened new horizons for scientists interested in investigating and understanding mechanical properties of materials at nano-scale. Hysitron fosters an environment and culture where innovation flourishes, teamwork is encouraged, and superior performance is rewarded.
Hysitron invites applications for multiple software development engineer positions from those aspiring to explore and succeed in the nano world. Hysitron, Inc. is an Equal Opportunity Employer M/F/D/V
Job responsibilities
The software development engineers would be responsible for developing test and measurement software applications for nano-mechanical testing instrumentation. Job deliverables would include:
-          Develop software applications in C based Labwindows CVI for Hysitron Instrumentation
-          Support the development of applications to address challenges in instrument automation and control
-          Test software applications using debugging and simulation tools
-          Perform software releases and software quality assurance activities
-          Participate in the design of new software products
-          Perform maintenance activities for existing products
-          Adapt and deliver on quality software development practices
Minimum qualifications
-          BS in Computer Science/ Computer Engineering/ Equivalent Scientific or engineering discipline
-          Min of 3 yrs experience in Instrumentation software development in an industrial or R&D environment
-          Expert at programming language C, knowledge of C++
-          Working knowledge of various communication protocols, e.g. USB, RS232, IEEE, RS485, TCP/IP, Modbus
-          Knowledge of general software design/documentation processes in test and measurement systems
-          Proficient problem solving skills
-          Strong analytical and technical skills
-          Excellent communication and interpersonal skills
Preferred Qualifications
-          Proficient with LabWindows CVI and XML
-          Working experience with DSP(Code Composer Studio) and/or FPGA level programming
-          Exposure to digital electronics and instrumentation
-          Working experience in Robotics interface programming
-          Experience with Controls/Automation engineering
Application and Information
Qualified candidates should send a letter of application and their resumes to (please include ‘SW Engineer’ in subject line):
Hysitron, Inc.
10025 Valley View Rd
Eden Prairie, MN 55344 USA
Phone: (952) 835-6366
Fax: (952) 835-6166
E-MAIL: [email protected]
Web: www.hysitron.com

This position is still accepting resumes/CVs.

How do I send e-mail to a distribution list using LabWindows/CVI?

I need to be able to send e-mail to a user-defined distribution list using LabWindows/CVI? Has anyone done this? Any ideas where I could look?

I commented on something similar to this awhile back. My issue was that I had the base version and didn't have the Internet classes. So this external app worked like a charm
It has a lot of command-line inputer options to use as well.
http://forums.ni.com/t5/LabWindows-CVI/Need-Help-for-Sending-Email-with-LabWindows-8-5-or-9/m-p/1095...

How can i display the signal out of a FFT block to a graph?

What conversion is required in order to convert a the output of a FFT block to a waveform display? The signal input to the FFT block is a binary pattern signal!

Hello St Augustine,
Unfortunately, I cannot open these files that you have attached so I cannot tell you for certain where your problem lies. However, if you are using one of the FFT VIs from the Analzye>Waveform Measurements sub-palette, then you should be able to wire directly from the VI to a Waveform Graph. Make sure you are trying to wire to a Wavform Graph not a Waveform Chart. If you are using the FFT VIs on the Analyze>Signa Processing>Frequency Domain sub-palette, you should also be able to directly wire into a Waveform Graph, but please refer to the KnowledgeBase document linked below for more information about plotting complex numbers.
http://digital.ni.com/public.nsf/websearch/C010A823CEA80D5386256938005A066E?OpenDocument
Rega
rds,
Jyoti F
National Instruments

How can I use the Diadem FFT Analysis GUI to give me multiple outputs given multiple inputs?

I have a few hundred channels I would like to perform FFT analysis on. They are mostly of different lengths, but I know I will have groups of 7 that will have the same number of data points. The default GUI will accept those 7 sets since they are the same size, but it will only give me one output as a combination of the sets. Is there a way to get Diadem to give me an FFT output for each set without having to select each data set individually?

The way it worked with the default channels, I had to make sure I wasn't going crazy because the way you demonstrated worked very well for me. That being said, for some reason what I am doing does not work. I've recently found that it is in changing the details in the GUI that makes my output different than yours. The differences are as follows:
1) I do not use a time channel. That is always left blank.
2) in the 'Window Functions' tab, I change the window type to Hanning
3) In the 'FFT Functions' tab, only amplitude is checked with the properties 'Peak amplitude', No Third/Octave, and Average amplitude is changed to arithmatic.
4) In the 'Time Intervals' tab 'Length/Start/Overlap' is checked, Interval length is changed to 1024, and overlap (%) is changed to 50.
I've also found that changing any number of these details from the default will cause my proplem to crop up. I am fairly sure that most of those options are just as feasibly done to one channel as they are to multiple. Is this a bug, or am I misunderstanding a property of FFT that has gone over my head? Please try changing a few of those properties since it seems like it should work just as well for all the channels as it does for just one, but that doesn't seem to be the case.
Another point of confusion is that while the window previewing the inputs in the GUI will show all the inputs I have selected, the window previewing outputs only appears to preview a single unknown output. That is just a side note though.

How to use CAN256 and CAN257 in Labwindows CVI?

I am trying to learn about CAN programming in LabWindows CVI. None of the samples do anything other than generate cryptic error messages. I do not have a card or interface device yet, but reading in the help files I found this:
"NI-CAN provides a virtual CAN card with two interfaces, CAN256 and CAN257. The two virtual interfaces are connected by a virtual bus. When you write CAN frames to one virtual interface, those frames are received by the other virtual interface, and can be read as channels. This feature allows you to read and write CAN data in the same manner as two real CAN interfaces connected by a real CAN cable. The conversion does not require real NI CAN hardware, and your application is not required to check for specific CAN IDs."
I modified the Waveform ouput project and add CAN256 to the dropdown in the uir file. However when I run it, I get the same error message as always, error -1074388725.
Is there an example CVI code someplace to demonstrate the use of these virtual channels?

Thanks Drew.
Ultimately, my customer provided me with a WriteCAN256.vi and ReadCAN257.vi that were perfect for my needs. The WriteCAN256.vi along with my NI USB 8473s allowed me to provide data collection on multiple CAN devices and to verify that my Software can handle all data types from CAN devices.
Note: My customer allowed me to share his .vi's. They are enclosed ...
Best Regards,
Don W
Attachments:
CanBus Read (Frames)_85.vi ‏55 KB
CanBus Write (Frames)_85.vi ‏48 KB

How to use the checksumdll.lib in LabWindow/CVI to create CRCChecksum();

Hi All,
Any one know how to use the checksumdll.lib in LabWindow/CVI to create CRCChecksum() ?
Thank you.

Do you ave some documentation about that dll?
Have you looked into dll properties searching for vendor name? Maybe you can look int vendorìs site and obtain some help.
Ultimately: are you forced to use that dll or can you use any software to calculate the checksum? There are several CRCs that you can use: provided you know which is the type used you could find an algorithm to calculate the CRC and check an existing one.
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos?

FFT in CVI

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