DAQ_START FOR Multiple Channel Data

Hi dears ;
Normally we use Scan_start DAQ API to get multiple channel data but i want to get data using Daq_start for multiple channel
but i dnot want to use this api like Scan_start by giving its second parameter -1 for all channels
i want to use this api in seperate thread for each channel and i want to get the data from 8 channels simultaneously using this api.
plz send code in vc++.if the solution is not possible then send me alternate way.
Detail:
There are 8 threads they are running simultanously and every thread want to acquire data from their corresponding channel i.e thread one from channel one thread 2 from channel 2 and son...all the threads goes at the same to acquire the data and come back after one minute and this process continue untill quit the application
please tell is possible or an altenate solution for this requirement.I donot use Scan_start to get the data of all the channels in one buffer i want to get the data of each channel in its own buffer.
                                 please tell as soon as possible
                                                                         thanks
                                                                                                ajmal

Hello ajmal,
There are a couple reasons why your idea probably won't work. First, it looks like you are using Traditional (legacy) NI-DAQ functions. The Traditional NI-DAQ driver is not multi-thread capable. Meaning that only one thread will be able to access the driver at a time. Also, it is not possible with Traditional NI-DAQ or NI-DAQmx to have multiple analog input tasks running simultaneously. Is there a particular reason that you don't want to read all the channels in the same task and separate the array into a different sub-arrays for each channel?
-Alan A.

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I am creating a program that will obtain data from all 16 channels of the PCI-DAQ6023E. I keep running into the 10609 Error "Transfer in Progress" when trying to compile and run. How do I set up the code to allow the DAQ card and Visual Basic to analyze all 16 channels at the same time?

Greetings,
Most of the time when I see the error 10609 Transfer in Progress it is because multiple calls, such as an analog config or analog start, are being called to the same DAQ device at the same time. Both calls are fighting for the DAQ card's resources. This is an issue with your program.
I recommend that you take a look at an example program, such as our simple AI example in Visual Basic which can be found in the following directory: \Program Files\National Instruments\NI-DAQ\Examples\Visual Basic\_Getting Started\AI.
You will see a Component Works control called CWAI. If you right-click on this control and choose properties you will be able to select the channels you wish to read from. You will want to read from all 16 channels by using a
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You could also take a look at the following example available on our web site.
Continuous Analog Input on Multiple Channels Using Visual Basic with NI-DAQ Function Calls
http://venus.ni.com/stage/we/niepd_web_display.DISPLAY_EPD4?p_guid=B45EACE3E25156A4E034080020E74861&p_node=DZ52302&p_submitted=N&p_rank=&p_answer=&p_source=Internal
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I have peaks and valleys from multiple channels with different time stamp but I am not able to log to a single file. Any idea on how to do this?
Attachments:
Single Point Peak Valley Log.vi ‏53 KB

Hi Dennis,
Sorry for that I have modified the VI.
Because the peak and valley of every channel will occur at different time and I want to log the peak/valley with the time stamp.
How can I log them on the same file.
Attachments:
Single Point Peak Valley Log_Mod.vi ‏53 KB

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Again help require
I m using
Config_DAQ_Event_Message with CallBack Functon
Scan_SetUp
Scan_Start
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If I give total no of chanels in Scan_setup then it creates exception with Config_daq_event_message if I donot use Cofig_Daq_Event_Message then it all works correctly and data from 8 channels is acquired correctly in double buffer but i must use callback with config_daq_event_message,Scan_setup,and Scan_Start API to get double buffer mutiple channel data acqusition. thanks

Hello,
Please see the response to your original post:
http://forums.ni.com/ni/board/message?board.id=231&message.id=3322#M3322
Regards,
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I want to acquire data for multiple channels using PCI 6120 that works on traditional DAQ. I cannot access more than one channel, can someone help me or if someone has data acquisition vi for PCI 6120, please send me over . Thanks

I have PCI 6120 card and I want to acquire data for more than one channels. I'm using traditional DAQ to get it. But it does not work for more than one channels. If someone has a data acquisition vi for PCI 6120. Or some suggestion how to aquire data please let me know.
Thanks

Hello DSPGUY1,
You can definetly acquire from several channels. For your convenience, I have appended below the content from help that tells you how to configure it:
"channels specifies the set of analog input channels. The order of the channels in the scan list defines the order in which the channels are scanned during an acquisition. channels is an array of strings. You can use one channel entry per element or specify the entire scan list in a single element, or use any combination of these two methods. If x, y, and z refer to channels, you can specify a list of channels in a single element by separating the individual channels by commas, for example, x,y,z. If x refers to the first channel in a consecutive channel range and y refers to the last channel, yo
u can specify the range by separating the first and last channels by a colon, for example, x:y."
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Applications Engineer
National Instruments

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Attachments:
Data Triggering.vi ‏116 KB

Faizah wrote:
I am obtaining voltage values ranging from 0.6-6 V.
I only want the data to be written to the text file when the difference in voltage (DeltaV) from one data point to another is greater than or equal to 0.04 V.
Your code does not do what you describe above..
I just want to make sure I understand your request...
Let's say you have the following signal:
0.00
0.01
0.00
0.03
0.02
0.01
0.03
0.04
0.07
0.05
0.08
0.03 < delta greater than 0.04, so start recording
0.11
0.21
0.45
0.93
2.87
5.85
5.86 < delta less than 0.04, so stop recording
5.87
5.89
6.00 < delta greater than 0.04, so start recording
5.85
5.86 < delta less than 0.04, so stop recording
etc..
Is the above what you are describing?
Right now, your code does this:
0.00
0.01
0.00
0.03
0.02
0.01
0.03
0.04
0.07
0.05
0.08
0.03
0.11
0.21
0.45
0.93
2.87 < threshold greater than 1 so reset timer
5.85 < threshold greater than 1 so reset timer
5.86 < threshold greater than 1 so reset timer
5.87 < threshold greater than 1 so reset timer
5.89 < threshold greater than 1 so reset timer
6.00 < threshold greater than 1 so reset timer
5.85 < threshold greater than 1 so reset timer
5.86 < threshold greater than 1 so reset timer
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2.21 < threshold greater than 1 so reset timer
1.09 < threshold greater than 1 so reset timer
0.98
However, you did not provide a set start time to the Elapse Time (I never use Express VI's so I'm not sure what will happen..) However, something does not appear correct with the logic. I'd have to check.

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hi sir;
i want to get the voice data from 8 channels in 8 different
buffers.The acquisition should be continious.Please tell how this will
be possible using daqmx API's and what procedure should be
followed.Also specify what API's should use.Please donot say the
tradition answer "see the National instruments examples
etc.etc".Please tell complete sequence of API's.
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Duplicate post.

Etherchannel setup for multiple channels

I have one 3750x and four 2960s. I want to set up etherchannels with two fiber pairs for each 2960 to two interfaces on the 3750. Does the port channel number on the 2960 have to match the port channel number on the 3750 for the two interfaces the fiber is plugged into? For example, port channel 1 on the 3750 g1/0/5 - 6 and port channel 1 on the first 2960. Then port channel 2 on the 3750 g1/0/7 - 8 and... should it also be port channel 2 on the second 2960? The instructions aren't very clear.
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How can we enter ONE manual BRS for multiple posting dates?
Below is the scenario for which we need multiple posting dates in one bank statement.
We receive and enter in SAP the Bank reconciliation statement at the end of every month. The system considers Posting date as end of the month ( the entry date or a single date what we enter). The transactions however belongs to many dates of the month. So while posting the bank statement system considers only one posting date and picks up the exchange rates of one date ( that is the posting date). It results in undesired exchange rate differences.
To elaborate more please check the following example:
1. Incoming Payment on 01-12-09 in USD (USD = Foreign Currency, AED = Local Currency ) with Exchage rate 3.8.
2. Incoming Payment on 06-12-09 in USD with Exchange rate 3.9
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I hope I am able to communicate properly.
Waiting for your expert opinion forks.
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Hello,
I recieve the appended error message when attempting to use DAQmx Read in my VI. LabVIEW is telling me that I am attempting to read a single channel when my task is configured for multiple channels. However, as you can see in the task configuration pane, that is not the case! If I attempt to use DAQmx Read to generate a waveform with multiple channels, the VI executes without error but I do not want a 1D waveform array.. Any tips?
Regards,
Steve
Solved!
Go to Solution.
Attachments:
multi_chan_errr.JPG ‏42 KB
channel_Vin.JPG ‏108 KB

This is exactly why I ALLWAYS hide my DAQ Tasks inside a "Resource Module"
As I use the term a "Resource Module" is a special case Action Engine tha exposes only that subset of functionality that a specific project needs to take on a given resource external to LabVIEW. And, it provides a single point of entry to access that resource by keeping private data private. Had you used the technique here you would have had one vi to look at. and, there likely would have been no "Reconfigure to add channel" method available to cause trouble.
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Is there a way to acquire a set number of points from multiple channels?

I had set up a VI to use AI ONE POINT.VI for multiple channels. Getting one data point for me is useless. I need, say, 100 data points from multiple channels at once. Is there a way to do that? Is there an example program I'm not seeing that already does that?
Thanks!
p.s. I have Labview 6.1

Hello,
Thank you for contacting National Instruments.
As Dennis had mentioned, there are many example programs that ship with LabVIEW that demonstrate how to take measurements from multiple channels with either a finite or continuous amount of data to be acquired. In LabVIEW 6.1 you can find these examples by going to Help >> Find Examples >> Hardware Input and Output >> DAQ >> Analog Input >> General.
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DAQ_START FOR Multiple Channel Data

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