How to Read from multiple channels

Dear Sir
I am acquiring data using FP-RTD-122 using OPC Client software. I ahve made one socket for that and i am using command
CWDataSocket1.AccessMode = cwdsReadAutoUpdate
CWDataSocket1.URL = "opc://localhost/National Instruments.OPCFieldPoint/FP Res\FP-RTD-122 @1\Channel 0"
CWDataSocket1.Connect
v = CWDataSocket1.Data.Value
where v is a variant type.But this is 8-channel RTD so how can i read values from all channels using single socket connection Because at presnt i have to use 8 sockets for all eight channels.

At least as of FieldPoint 4.0 and earlier (I do not know about 4.0.1 or later), the OPC Server did not support multiple channel analog items. Thus to read all eight channels of a FP-RTD-122 module, you would need 8 separate socket connections. For discrete modules (boolean), the "All" tag, is treated as a single 8 or 16 bit number.
Regards,
Aaron

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Data acquisition from multiple channels.

Hello
Right now, I am able to acquire the signal from a single load cell and display it.But I would like to know of how to acquire acquire signals from two load cells simultaneously.I am using Labview 6i and I am using AI S-Scan with AI config to acquire the waveform.It would be of great help if you could suggest a simple method to acquire the signals.
PS: Please find the attached file used for acquisition from a single load cell.
Looking forward for your reply.
Manasa
Attachments:
test 4.vi ‏102 KB

Hi Manasa,
If I understand what you are trying to do, it is relatively
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I was unable to run your vi as it was missing some of the subVI’s
from your application. However, your
attachment was sufficient to see what you are trying to do.
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In the I/O Channel Constant, you can add
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put 0,2.
2.
The AI Single Scan VI will now read from
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configure the output of this VI for viewing by first putting the data into an
array using the Build Array VI. It can
then be plotted in a waveform graph. (see attached screenshot ReadtoGraph.jpg
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Just a few notes about “simultaneous” sampling:
Most of the NI data acquisition cards have a multiplexer
between the various input channels and the Analog to Digital (A/D) converter
creating a very small delay between each channel (usually ms range or
smaller). NI does make several data acquisition
cards that can perform true simultaneous sampling, meaning that there is an A/D
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For the large majority of applications, the small delay
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Jared T.
Attachments:
ReadtoGraph.JPG ‏21 KB
ChannelConfig.JPG ‏288 KB
WaveFromChart.JPG ‏61 KB

Acquiring Analog Input from Multiple Channels in Labview

Hello,
i am working on a VI where i need to acquire signals from multiple channels in Labview using NI-9129.Initially i want to acquire contineous input signals (voltage and current) and display it on the graph.
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Attachments:
Voltage-Current VI.vi ‏81 KB

Engr_tech wrote:
i think i already have the tdms for data logging.as far as the tdms data logging is concerned,when i enable the logging mode to "read and log" the data logged inside the excel sheet would be seperate for current and voltage.?
Is it practically possible to acquire data from 4 different channels and plot them.if yes,then am i right to assume that all i need is to modify the current VI for four channels having all of them in parallel.
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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?
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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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Edited by: user9003827 on Apr 13, 2010 3:42 AM

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Go to Solution.
Attachments:
ReadFileAndAverage.vi ‏48 KB
acquiredWaveform.txt ‏605 KB

Thanks again DFGray for the comments.
After the correlations to find the peak positions, i just take the max value. And you are right the accuracy is limited by the number of samples per cycle. Perhaps it would be clearer if you see the code.
1) Basically I get a signal on the up and downslope of the sine wave. On the down slope however the signal is negative, i.e. its is flipped. So before I shift and average...I 'cut' the waveform into 4 (when cycles per buffer = 2, then I get 4 signals, 2 on the up slope and 2 on down slope) bits. Counting from one, I flip the even number, cut it, and but an array of waveforms which is then sent to be convolved and shifted.
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Attachments:
SubVICutWaveforms.vi ‏37 KB
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How to Read from multiple channels

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