How to freeze analog output ?

Hi,
In my LabVIEW program, I need to freeze analog outputs (keep the last value) when appears for example an emergency stop.
In this program, sometimes I use "simples" values to write outputs and other times I use waveforms.
Is there an easy way to freeze outputs in both cases ? (a better solution than modifying all the VIs using analog outputs )
Thaks for your help !

Hi cpit,
when you need an emergancy behaviour in your output VIs you have to program it...
An easy way would be: IF emergency condition is met THEN don't output values.
So a simple case structure will do the trick...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

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How to switch analog output between two waveform frequencies

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Hi,
I'm trying to get a small project working in DasyLAB 9.0.2 and I need some serious help.
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NI-DAQmx: Error Message
Driver: Task DA00, Version: 0.15
Possibly Reason:
-> The module can process the number of "values to be written".
File: ProcessData_KONTINUIERLICH.H, Line: 39
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NI-DAQmx: Error Message
Driver: Task DA00, Version: 0.15
Possibly Reason:
-> The driver does not use all NI-DAQmx task channel names. This is not valid, reconfigure the module to use all task channels.
Note: A NI-DAQmx task for analog / digital / frequency output must not have more than 16 channels. If you need more than 16 channels for the output, you must use more NI-DAQmx tasks.
File: MODUL_DA.C, Line: 2131
Any help to point me in the right direction would be greatly appreciated.
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Thanks in advance!
Chris

Here's what I did using the NI-DAQmx simulation mode:
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    Note - my simulation did not work without the Analog Input. It generated no data. That may be an artifact of the simulator, but, once I put an Analog Input on the worksheet, it ran okay.
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- cj
Measurement Computing (MCC) has free technical support. Visit www.mccdaq.com and click on the "Support" tab for all support options, including DASYLab.

How to store the output of a analog to digital converter into an 2D array

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nitinkajay wrote:
I want to know how to store the output of a analog to digital converter into an 2D labview array.
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Grabbing image using camera OR performing data acquisition using DAQ card OR some other way????
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Make your LabVIEW experience more CONVENIENT.

How to avoid delay during analog output generation by changing its frequency?

Windows XP
LabVIEW 7.1
PCI-6036E + BNC-2120
Hi,
I am going to create a vi to generate an engine speed sensor signal (a simple square wave with specific missed pulses, in my case 58 pulses “teeth” and 2 missed pulses “missed teeth”) as an analog output but in addition give me the opportunity to control parameters for example frequency online to simulate the engine speed changes during running that vi. For this purpose I have started with “Continuous Generation.vi” which is available in NI Example Finder under the following path:
Hardware Input and Output > Traditional DAQ > Analog Output > Continuous Generation.vi
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At the first try it looks that it works properly but when have a look on that more accurately with Oscilloscope (fortunately I have a good one: Agilent 54621A – 60 MHz, 200 Ms/s) obviously there is a gap (delay or Jitter) whenever I change the engine speed. It is also attached in Signal generation_problem report.doc file.
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Any hint is appreciated.
regards
Attachments:
Signal_generation_NIsupport.zip ‏81 KB

Hi Roozbeh,
The following example will allow you to vary the pulse train frequency during run time.
Thanks,
Lesley Y.
Attachments:
GenDigPulseTrain-ChangingSpecs.vi ‏75 KB

How to synchronize analog input and output from two different USB daq boards

Hi all,
I have two very differnt USB boards the NI USB 6008, which I am using to acquire the data (Analog Input) and a NI USB 9263, it is an Analog Output only board that I am using to deliver a signal (in this case a square pulse). The reason why I am not using the 6008 Analog Ouputs is because I need to deliver negative voltages and need the full +/-10V range.
Looking at similar posts I am pretty sure that I can't use an external trigger or a shared clock, I also tried to use the synchronization of timed structures but no cigar.
I am including a quick vi that I whipped out showing how the signal jitters due to the lack of synchronization. The AO from the 9263 connects to the AI in the 6008 in this example.
Solved!
Go to Solution.
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Test Pulse.vi ‏117 KB

I talked to a specialist in the phone and tols me that it is not possible.

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I have a PCI 6251 card, and using DAQmx C function to generate a wavwform. (single channel ).
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This is getting to be a common question!
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John Weeks
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Phone (503) 620-3001
Fax (503) 620-6754
www.wavemetrics.com

How can I use two analog output channels simultaneously?

I am using PCI6110 DAQ card. I want to run two separate VIs on one computer. Each VI output a waveform to one analog output channel. How can I do this simultaneously without interfering each other?
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Hi Stephen,
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I have to generate a ramp at a decreasing frequency. I use a shift register in a "for" loop to decrease the rate of the analog output. Unfortunately, the loop or the analog output initialisation take a too long time delay..
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Any help is greatly appreciated
Thank you

Hello;
I'm attaching an example VI that shows how to change the output rate on the fly.
Hope this helps.
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aochangeonthefly.zip ‏47 KB

How to reset buffer pointer for analog output generation?

I am doing a finite analog output generation on a USB-6216
Sequence of events:
DAQmx Create Task
DAQmx Timing (finite samples, 1000Hz)
Use DAQmx timing property SampQuantamples per channel to set buffer size
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Until finished
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Hi CDancer,
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I would have a look at some of the DAQmx examples that come installed with LabVIEW. The following example would be particularly relevant I feel
Cont Gen Voltage Wfm-Int Clk-non Regeneration.vi
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Many thanks,
Andrew McLennan
Applications Engineer
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DAQmxCreateVoltageChan((Ao1taskHandle,"Dev1/Ao1","",-5.0,5.0,DAQmx_Val_Volts,NULL);
DAQmxCfgSampClkTiming(Ao1taskHandle,5000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000);
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Thanks
Enky

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C:\VXIpnp\WinNT\NISCOPE\Examples\c\MStudioC++\5112Sync
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Attachments:
Multiple_NI_PXI-5112_Synchronization_Demo.llb ‏151 KB

How to combine the analog input and analog output vi's

Hi !
I have a perfectly running triggered analog input acquisition vi. I have a seperate vi for analog output that's running perfectly too. Can someone tell me how to combine these two operations so that I could get a vi that does simulataneous AI and AO without missing triggers. I have tried all the different kinds of configurations suggested by NI support but nothing seems to work. Can someone help ?
thanks,
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Attachments:
dac_good.vi ‏77 KB
adc_good_fw.vi ‏124 KB

Shiva;
I'm attaching a good Application Notes that shows how to synchronize multiple DAQ tasks, in Labview.
Hope this helps.
Filipe
Attachments:
Advanced_Sync_Techniques_for_DAQ.zip ‏166 KB

How to equalize an analog output by a known frequency response?

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How can i synchronize analog output and analog input timings to generate and measure voltage at the same time.

how can i synchronize analog output and analog input timings to generate and measure voltage at the same time.

Read this Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/3615#toc3
And also refer to this link where You have repeated this question.
PS: Please stick to one thread. That way, its easier to keep track of your query and answers

How to freeze analog output ?

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