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Controlling Sampling Rate with NI DMM/NI SWITCH Handshaking?

March 13, 2017, 1:10 pm
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What is the best way to control the sampling rate when using the NI-SWITCH/NI-DMM handshaking? I realize that often you are handshaking to take the measurements as quickly as possible. However, there are occasions that I'd like to really slow that process down.

 

I have built an Action Engine for the NI-DMM and for the NI-SWITCH and am wanting to know where to implement the timing "slow down".

 

Is it by setting the Scan Delay within the niSwitch Configure Scan Trigger VI?

 

Otherwise I'm not sure how to do this and get a time stamp for each measurement that is taken for each channel.

 

Thanks,

 

Kellen

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Probe on error wire impacts timing considerably

March 13, 2017, 1:11 pm
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So I noticed some odd behavior and am curious as to what is going on "under the hood".  Obviously it doesn't impact my real code or anything, but I found it interesting.

 

I was playing around with a simple cDAQ output task and allowing it to time my loop (ignore the bad code, it was me just testing stuff).  I wanted to see how stable it was, so I dropped a pt-by-pt histogram in to look at the delta T... it acted as expected

AO Task.PNG

 

After running for a bit, the histogram looked about as would be expected

AO Hist1.PNG

 

However, I later dropped a probe on the error wire and it greatly impacted the timing in the loop.  Note that this doesn't happen if I probe any other wire - but reliably happens on error probe.

AO Hist2.PNG

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Labview 2016 (linux Red Hat 32 bit) -error "Internal Warning 0x9120BBD8 : "CPUInformation.cpp", line 408"

March 13, 2017, 1:14 pm
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Hello,

 

if somebody can help me :-)

I try to migrate my projects from labview 2010 to labview 2016. it's good when i run my code in labview.

but if i build a binary i have an error: Internal Warning 0x9120BBD8 : "CPUInformation.cpp", line 408

 

i make a second test with very basic code (2 num ctrl + 1 num indicator) same error

 

my OS is red hat 6 32 bits

 

 

 

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Get Cluster Information VI preserves data?

March 13, 2017, 1:35 pm
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I found the data typo parsing vis in labview 2015 and thought these could be useful.

 

Specifically the "Get Cluster Info VI"  Takes a cluster and returns an array of variants, one for each element in the cluster.  This is great except for the fact that all data is returned with the default value.  Is this how the function is intended to run?  Or is this a bug.  Unclear to me.  I can not see why I would not want to preserve the data with the type.  Is there a work around to preserve the data with the type.

 

 

 

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Newtons4th PSM1700

March 13, 2017, 2:17 pm
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Does anyone have experience communicating with a Newtons4th PSM1700 PsimetriQ frequency analyzer?  I am trying to set a neutral bias value of 1.25VDC, but I have struck out so far.

 

I am interfacing with LabVIEW 2015 via a GPIB bus.

 

Thanks in advance for any help.

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Capacitance testing

March 13, 2017, 2:22 pm
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Hi all! 

 

I have been browsing through the forums and reading some of the information.  First of all, lots of smart people here and I am impressed.  Secondly, I am not a student, I am a working professional building things for customers, so no worries about doing my homework Smiley Very Happy

 

I recently was presented with a project involving LabVIEW and on my own time am picking it up again.  I got a physics undergrad where we have built LabVIEW programs before in the lab, however that was years ago and I proceeded to get a masters in mechanical engineering and never used it again.  I know the basics, as you would say.. know enough to be dangerous.

 

Right now I am testing capacitance of *confidential* things and they stretch.  I want to start from scratch here.  I went through several tutorials and again read through lots of old threads...

 

Does anyone have an idea on how to start in terms of literature, tutorials, videos, etc. 

 

I am here to learn, and if I get stuck will definitely ask!  Any samples and explanations and literature would be much appreciated.

 

Thanks!

 

-Chris Nee

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LabView work on Trible Juno?

March 13, 2017, 2:32 pm
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How to connect labview program in my computer to an oscilloscope

March 14, 2017, 6:43 am
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Hi

Iam quite new in learning Labview. I did a code for producing a sinus wave in Labview program. I want to send this sinus wave through a coaxial cable to an oscilloscope next to my computer to display the oscillations. When I do the connection between the computer and the oscilloscope I do not get any thing plotted , I just get a line. I included my code file below if you want to see it.

What am I doing wrong?

(Just to mention something: I get oscillations in my oscilloscope when I run a youtube video in my computer).

 

thank you very much

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Single call of "Open VI Reference" loads multiple clones of reentrant VI?

March 14, 2017, 7:16 am
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Fideling around with asynchronously calling reentrant VIs I observed following effect: after a single call of "Open VI Reference" with option "x40" (simultaneous reentrant calls) 5 clones of the reentrant VI to call showed up in the LabVIEW Taskmanager. This is easy to reproduce using the "Asynchronous Call and Collect" example shipped with LabVIEW:

- Change the order of elements in the "Pass option 0x40?" array on the left.

- Insert a breakpoint right after the call of "Open VI Reference"

asyncall_xampl.png

- open "LabVIEW Task Manager"

LVTaskmanager_beforun.png

- run the VI and refresh Task Manager view (F5)

LVTaskmanager.png

I tested it with LV2014SP1 and LV2016 with the same result.

 

I'm curious, if this is wanted behaviour!? First I thought LV loads a bunch of clones for performance reasons. However a second call to "Open VI Reference" while the first asynchronously called VI is still running doesn't make use of the clones already in memory, but brings up another 5 of them.

 

In contrast using "Open VI Reference" with the old school option "x08" and the "Run VI"-InvokeNode only a single clone appears in the task manager.

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CRC16 error with several entries

March 14, 2017, 7:26 am
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Hello,

I was trying to create a VI that:

1-Reads data from Serial Port. This data are strings containing several information and arrives each 500ms. On the end of each string, CRC is appended. I use % to separate CRC from other data.

2- For each string, my VI must, first, find % and remove the incoming CRC.

3- Then I have to check if the CRC of the string received is equal to CRC appended.

Please see this example:

CRC_fpanel.png

In this example, the incoming string is:

ETS3#1984;18,93;1030,36;44,85;57,87;0;ON;5,00;USB;0,69;3,20;16,62;-0,51;0,16;9,89;ON;0.000000;0.000000%4785

The CRC is 4785(hex) and was appended at the origin of the communication link.

Then, if I compute the CRC of the data (incoming string without the CRC) I should get the same value. But I get a wrong value (DBDB).

The interesting is that if I use this VI found here:

http://forums.ni.com/t5/Example-Program-Drafts/Inline-CRC-Reference-Library-CRC-32-CRC-16-and-CRC-8/ta-p/3500715

the value of the CRC is correct (option CRC-16-CCITT-xMODEM).

So if I am not wrong, the problem can be the fact that I am using the subVI in a loop since there is a First Call function included.

Can anyone help me with this?

Bellow there is a snippet of my VI

crc_check.png

 

Thanks a lot in advance.

 

Duarte

 

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Filter to Extract and Smooth DC Level

March 14, 2017, 7:40 am
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I am trying to filter and smooth the peak DC level of 100kHz sampled data. I can't seem to find a suitable filter that filters and smooths the data without rounding off the leading edge of the signal and/or creating new artifacts like undershoot, overshoot, extended rise time, etc. I have attached a VI with sample data. I have included some of the more promising filters I have tried. In the end I am looking for as flat of a DC level as I can achieve with minimal rise time at the 100ms mark without adding additional artifacts.   

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How to make a VI pop up above all other windows in 8.6

March 14, 2017, 7:58 am
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Hello!

I have a VI that when called on, pops up to allow a user to make a choice. My issue is that I cannot figure out how to get it to pop up above all other windows using LabView 8.6. I know there is a property node that works in 2013 called NativeWindow, but that doesn't seem to be a valid property in 8.6. Does anyone know of a way to accomplish this in 8.6?

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Silver Path Control Button does not prompt browse window (BUG?)

March 14, 2017, 8:49 am
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Hi Gurus,

 

I am not new to LV but new to this strange behavior. While starting to use LV2015 not too long ago, a co-worker spoke about the silver path control ceasing to work as expected. After a while of having a program running or if an error was encountered during the execution, the browse button for this silver path control will not prompt the browse window to appear…at all. You’d need to kill LV, restart it then run your VI to make it respond correctly for a while, but eventually the same behavior is seen. Initially I thought it was his computer presenting this behavior, but my workstation also got into that type of dance when trying to mimic.

Has anybody seen this?

Can anyone with LV2015 mimic this control, forcing an error perhaps?

What is the procedure for issuing a potential bug with this Silver path control in LV2015?

Thanks,

JR

 

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Showing front-panel of a VI (which runs on RT-target) via Ethernet on Laptop

March 14, 2017, 8:59 am
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Hello,

 

my question is about a VI, which runs on a RT-target (It is saved in the Project tree as marked with an arrow in the attached Picture). Lets assume, we start the VI with a Laptop over Ethernet cable. The VI has got a frontpanel which showss a graph and some parameters...

 

I noticed: If a Background image (which is saved on the hard drive disk of the Laptop) is added to the front panel, the performance of the graphs is extremely slowed down. Of course thats no important issue, anyhow it lead me to some questions:


Should a VI on RT-target at all be monitored by a Laptop via Ethernet-Cable? Or should on the Laptop run a second VI, which gets only some monitoring-data via nework-variables? What´s the difference?


Thanks very much!

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Combo box cannot produce backslash code / bug or not?

March 14, 2017, 9:00 am
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Hello,

I have got some problem using a (System) Combo box (LabVIEW 2015 32bit). I want to have two items: "Tab" and "Comma". Required values: "\t" or "Tab constant", and "," comma.

I have found this old post where an NI folk stated this is not a bug (I am not sure if I understood that post 100% however):

https://forums.ni.com/t5/LabVIEW/combo-box-HEX-style/m-p/219654

 

Of course I can do several workarounds, but is it just not possible to use directly a combo box for this task??

 

backslahs_combo_box.png

 

combo_box.png

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Reading Strings using OPC UA from a Modicon Premium (Schneider OFS Server)

March 14, 2017, 9:03 am
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I am busy testing an application that reads data from a Schneider PLC using their OPC server via UA. So far I have been successful in reading basic values but I am strugling to read a string using the OPC UA Read Tool in Labview.

 

I have mapped a symbol table on the OPC server from the PLC Source code (PL7) and I can read the first character of the string I want to read using the OPC UA Read tool set to Read a "Byte" it then returns the ASCII code of the of first character of the string located at this base address.

 

My question is how would I get Labview to read data past the base address supplied in as the Node Path on the OPC UA Read VI?

 

 

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Application not able to keep up with data acquisition error when sample number is low

March 14, 2017, 9:13 am
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Hi, having a slight issue trying to get a simple data acquisition VI do what I want (attached here). For reference, the DAQ is a usb-6009 (48kHz max) and I'm sampling the analog signal at 24kHz , to allow the digital channel to effectively sample at 24khz (though it is 'on demand'). 


What I want is for an analog input to be recorded when the digital input is high. If the code worked I would aim to implement this by taking the waveform data and appending it on a waveform through a shift register.


Unfortunately when I set the sample number to 1-10 (I would like to keep this low so that the data acquisition stops precisely when the digital input is 0) I get the error - why is this happening? 

Using samples = 25 means it works flawlessly , but this would be taking data points when I don't want them to be taken (i.e when the digital signal is off).

 

Thanks in advance! Smiley Happy

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Variant to Cluster

March 14, 2017, 9:16 am
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Hello.

Im triing to do a typecast for this variant (content below as copy/pasted from a probe of my variant).:

 

'topic' -> "pupil"
'norm_pos' -> [2]
(430.396E-3, 726.106E-3)
'method' -> "2d c++"
'confidence' -> 858.839E-3
'timestamp' -> 717.154E+3
'id' -> 0
'ellipse' -> {[2]
, [2]
, 137.336E+0}
'diameter' -> 64.408E+0

 

I thought to create a cluster which contains the above variablenames (topic,nor_pos,...) and variabletypes (string, array of doubles, ...) and insert the variant as well as the type template (my cluster definition) to some function. I never did typecasts in labview and would need some help here which functions to use for that.

 

Thanks a lot!

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Include .NET assembly created in Matlab 2015b in Labview 2013

March 14, 2017, 10:07 am
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I have generated .dll file ( .NET assembly ) with Matlab 2015b deploy tool based on .m function, I am trying to include generated dll in Labview 2013 but i have a problem with mxArray data type ? Can someone give me proper directions how to integrate generated dll with Labview and use function from it mlfUcitavanje_mape(mxArray pathname) ?

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trigger para camara NI 1742

March 14, 2017, 10:41 am
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