Digital trigger in cdaq 9172

June 9, 2016, 2:23 pm

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Hi,

 

I am setting up a continuous temperature measurement task using TC module 9213 and K type thermocouple. The acquisition starts using a Digital trigger. Pretty simple. 

 

I am using a cdaq-9172 8 slot chassis and what I have learnt that for PFI trigger operation, I can use slot 5 and 6 using any digital input module or NI 9205 PFI0 line in any slot position. I have NI 9423 DI module and NI 9205 AI module with PFI0. 

 

The problem is I have tried both these options as a digital trigger (NI 9205 in any slot and NI 9423 in slot 5 or 6), but none works! There is no issue in the labview code as it works without trigger and with trigger if I use NI 9188 chassis. 

 

Am I missing something?

 

Thanks!

Roy

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Get a cluster element value from a variant

June 9, 2016, 4:30 pm

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Hi

 

I am trying to get a cluster element value from its variant form

 

 

If I look at the variant indicator, the elements and their values are displayed. However, after Get Cluster Information.vi, which I expect to break up the cluster into its individual elements, all I get is the type information, not the value of the element. That is, looking at the Elements array, all that is displayed are 0's, I was expecting values and element names.

 

 

So my question is, how do I get the cluster element values?

 

Thanks

Creating a new LabVIEW Project from an existing large LabVIEW program

June 9, 2016, 5:12 pm

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Hello everyone,

 

I have a large LabVIEW program (~ 100 VIs) that was developed by several people over the years and I need to get this program under control. My first idea is to utilize LabVIEW Project. Can a new LabVIEW Project be build from an existing large program such as this (which includes NI-DAQ control, as well as other USB controlled third party instruments).

 

Any advice or suggestion would be most welcome !

Cheers ! 

'To .NET Object.vi' can't handle a 2D array of variants

June 9, 2016, 5:33 pm

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It gives error 1199 when fed a 2D array of variants. Why is this a problem for me? Because I tried to create a .NET analog of 'Write table to Excel.vi'. Why? Because In Excel 2016 it looks like Microsoft finally deprecated ActiveX automation used fro communication with Excel by both the shipped 'Write table to Excel.vi' example and Report Generation Toolkit.

 

When using ActiveX the Value2 property of Range object had a type Variant as seen from Labview. It could accept a 2D array of any type, including an array of variants (which, for example, could have been returned as a result of an SQL query from a DB). It was very convenient to be able to export such data as is, i.e. as a 2D array of variants, directly into Excel.

 

When using .Net interface though, the Range.Value2 property is of type '.Net Object'. So one has to use the 'To .NET Object' vi to convert. It works with 2D arrays of both strings and, say, doubles. They get exported to Excel just fine. But it can't handle a 2D array ov variants!

Real time Building of array and plotting data

June 9, 2016, 7:32 pm

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 Hello

 

I have a project in which I'm waiting for a string message coming to my Serial port containing two parameters from a sensor ,Tension versus position

I shall then plot  the two parameters to an XY graph as they are arriving to my port in order to build a graph which is continously updated with all the points came to the COM port (all tension readings versus the position of the reading).

 

I know that in order to plot the two parameters against each other I have to use the XY-Graph and for that ,I have to insert my data into arrays first and then give them to the graph.

 

The problem is that the serial message does not come at fixed interval (for example one message comes now ,the other may be after 1 minute ,and then another after half a minute ...and so on). and the graph has to be updated with the new points once they arrive (in addition to display the previous points too ofcourse).

 

I don't know where to start !! can someone put me on a track for that ?!

 

Note: I don't have any problems with the interpretation of the serial data ,at the end I shall have two numerical values which I shall then plot against each other

 

Thanks

 

 

Synchronous pulse generation and data acquisition

June 9, 2016, 9:31 pm

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I have my application where I must generate two pulses from two analog lines and synchronous my application must acquire data of these pulses when I have different loads for these pulses. Because the requirements are to have high sampling rate I am using two NI DAQ 6115 connected with RTSI.

I have in total 8 channels for acquisition on the two cards and two AO also spread, each card having one AO channel. Basic configuration is: two channels measurements for each pulse line in each board (one channel is current and the other voltage).

The pulse provision and acquisition must be synchronized. The basic analog part looks like in the attached image which was inspired from one of the DAQmx example “Multi-Device Synch-Analog Input-Finite Acq-Analog Start.vi”

For synchronization I setup AI as well as AO to receive on both cards on PFI0 a unique trigger signal provided by digital Port0\d0. For the analog out I did not find a good example and I setup channels as in the attached image.

My application has many variation of configurations: I could have active one channel AO in second board and different channels active in first board, so I can have any combination AI and AO of channels configuration from both boards, also pulses can have different duration or delays between them (you have attached one example of pulse). I think the analog part is good but I am not 100% but the problem might be in AO part.

Here are few instances of my test:

-Pulse generated in first board are correct acquired by channels from board one

-I set pulse in second board and I measure pulse with channels from second card. AI is triggered in this case but I got dead 0 acquisition while pulse is correct generated most of the time, very rarely I got the pulse. If I set 1ms pre trigger frames then the pulse is correct measured.

-I set and trigger both pulses and they are not generated but the AI measure noise.

 I need help as soon as possible, some examples with analog out from two boards synchronous connected.

Thank you,

Virginia

Triggering Multiple Events from Event Structure

June 10, 2016, 3:51 am

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I have VI with multiple Controls.

I have an event structure that triggers an event for "Value Change" for each of the Controls.

I would like to perform an action (single button press) that triggers all of the 'value change' events in this event structure without actually changing the values in every control.

Is this possible?

 

Many thanks, Alec

Append waveforms in a single TDMS: How to track the time if waveforms are not-continuous?

June 10, 2016, 4:30 am

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Hi !

 

My application writes 50kHz waveforms, in segments of 1sec, to a TDMS file, depending an externally triggered condition.

 

Every 1sec-waveform has a t0 with the absolute time. 

 

 

Which is the recommended way to store discontinued waveforms, into a single TDMS, without losing the t0 timestamp of each Wfm segment? I tried playing with the wf_time_pref property without success. 

 

Obviously, I want to avoid writing explicitely the time, given the high rate and amount of storage needed.

 

Dimitri

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gps myrio

June 10, 2016, 5:22 am

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Hi,

Can someone please help me with reading gps data using a myRIO?

Thanks

Best way ot graph analysis

June 10, 2016, 6:42 am

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Greetings everyone, I am working on a project that requires detecting a particular event that, from the looks of it so far, can be seen in the gathered data of a sensor. As you can see in the screenshot below, the blue data marks a regular interval of cycles, and the red shows a series where the event was forcibly induced to occur every iteration.

We are however reluctant to just go for a "top ceiling" approach, because the sensor throws a spike every now and then that could be interpreted as the event, plus the top values vary depending on user input and mechanical variables, and a max value won't work for all cases. I have heard about LabView graphical analysis toolkits that could help with this, could anyone please point me to an example, video or whatever that helped me analyze the graphs and find the event?

how to use QT compiler when dll and header file requires QT preprocessors and headers

June 9, 2016, 10:25 pm

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C++ dll have a header file that contains QT headers . while i include paths of those headers in Import shared library wizard more missing headers pops up. is there an efficient way to do this so that QT compiler can be used with labview so that dynamic link library can work in labview.

 

import shared library wizard:

Create Network Stream endpoint - pre-allocation for strings

June 10, 2016, 7:01 am

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Hi,

 

I would like to use ellement allocation mode input to pre-allocate memory on my RT target. My concern is how to allocate memory for specific string size.

 

Due to documentation

"pre-allocate specifies that buffer memory allocation occurs when the endpoint is created. The element wired to the data type input determines the amount of memory allocated for each element. If a larger element is added to the buffer during run-time, additional memory is allocated dynamically. "

 

I understand that if I wire string constant to the data type, 40 to the buffer size I will receive buffer for 40 strings. But how long strings ? One character ?

I don't want let memory manager to run after endpoint creation so I would like to allocate enought big memory space (for example 40 string, 10 characters each).

 

Is it possible to do it connecting string constant (e.g. with 10 characters) or I have to put my specific size string to the cluster ?

Another maybe trival question, is it possible to check how big buffer was allocated by this VI ?

 

Kamil

cRIO target vi when starting running disconnect from cRIO module from ethernet network

June 10, 2016, 7:18 am

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I am using cRIO-9073, I have FPGA vi code and cRIO target vi code. When I start
the FPGA vi code , it runs continuously without issue. However in addition,
when I run cRIO target  vi , it runs slows ( results displayed in front panel)
and disconnects the cRIO-9073  from Ethernet network. Also, I can reconnect
unless I have repower the cRIO-9073 itself. I have attached the cRIO target vi
and FPGA vi above.
Kodjo Komedja

.NET Application developer
Please, I am looking forward your response.

Labview Vector pid

June 10, 2016, 7:27 am

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I'm trying to use LabVIEW's PID toolbox to control three inputs [a,b,c] that are multiplied by a [3x3]array for a result value of [x,y,z] Attatched is my attempt using a pid contol and a sub vi that is a simulator for the hardware I'm using. The primary difficulty I have is trying to set up the PID to take into account the fact that each every input changes every output. A seccondary issue is that the system has a non linear responce so, although I can use a matrix to provide an approximation for where I should go, I need a PID control to do fine tuning.

Finding PSP variables in .exe built application

June 10, 2016, 8:15 am

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I am making a program that scans for computers in our lab by looking for a specific PSP variable container. In development mode this works fine. However, when I build an .exe this no longer functions. I suspect the "Local PSP Variable Enginer" node behaves differently in a .exe from previous experiences using static references in .exe's. Does anyone happen to know what issue I might be running into?

 

 

Thanks

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I want to compare the "screen brightness" of two images using a template image and an acquired image

June 10, 2016, 8:36 am

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Mostly looking for suggestions on the best way to go about this. Im trying to run a test that will allow me to compare the screen brightness of an LCD using a webcam. Essentially i will cycle power on the screen and every so often the screen will be incredibly dim. Im thinking i should be able to use the subtract feature with the two images and if i have a normal screen it should produce a close to 0 result, whereas the dim screen should give a non zero value (pixel wise) but so far have not been succesful.

What's new in LabVIEW 2016

June 10, 2016, 8:45 am

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OK, I know we still have a couple months to wait.  But anybody heard any rumors?  What can we expect in the newest version coming out soon?

Change the scan order of IMAQ Count Objects in LabVIEW

June 10, 2016, 8:50 am

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By default, IMAQ Count Objects 2 scans the image from top to bottom. I need it to scan from left to right so that the object indices are displayed in a sorted order from left to right. How can I do that without migrating from Vision Builder as I dont have its license?

Question about Verson information in the FPGA build spec

June 10, 2016, 9:18 am

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For a FPGA target in the build specification in the Information category, there is the option to enter revision information and to have it auto increment. Is this information accesible anywhere else?

 

For instance, can the RT ask the FPGA bitx file what version it is? Or ask the FPGA what version it is running?

 

If so, how is this done?

 

Currently I have a seperate set of front panel controls on my FPGA VI to handle this kind of versioning, but if I can use the version feature in the build spec, I would change that.

 

Thanks!

Control could not be found ActiveX

June 10, 2016, 10:30 am

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Hi,

Sorry about the basic nature of this question, but I am unable to find the ActiveX control for WinDaq anywhere in LabVIEW. I have downloaded the ActiveX Control Library from http://www.dataq.com/products/dataq-active-x/ , but when I try to add the WinDaq control to an Active X container in LabVIEW, it does not appear on the drop-down menu (see attached photo.)

 

Is there anything else I need to do to be able to access WinDaq from LabVIEW using ActiveX controls? Please note that I have already reparied the RunTime engine, and I know that the code works because I am in the process of transfering it from a working computer to a new computer. My issue is that I can not find the right ActiveX control on my neew computer.

I am using LabVIEW 2013.

Thanks for your help,
Andrew Nelson