FP-AI-110 Multiple Channels - Signal Degredation

We have a FP-AI-110 set up with a FP-PS-4 and communicating back over a FP-1000. Set-up to read Current. -21 to 21mA
I had a customer ask if connecting more than one signal input line to the AI-110 would cause signal loss on the multiple channels, getting worse with the more channels that are connected.
Is this a concern with this module?
Ryan Vallieu
Automation System Architect
Solved!
Go to Solution.

The above is incorrect, I was getting questions through a second non-technical party trying to translate....
They really wanted to know the input resistance on the channels that causes the voltage drop for the current sensing, and what the minimum voltage would be. I see from the literature that it is 100 Ohms resistance on the inputs.
But then I see later in the operations manual that it lists 60-150 Ohms.....which is correct?
Current Inputs
Input impedance................................60–150 Ohm
Ryan Vallieu
Automation System Architect

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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
straightforward to configure your application to acquire data on two channels.
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.
Here is how to add channels:
1.
In the I/O Channel Constant, you can add
additional channels by using a comma or a semi-colon. For example, to scan the first four channels
you would put 0:3 in the constant (see attached screenshot ChannelConfig.jpg). To scan the first and third channel you would
put 0,2.
2.
The AI Single Scan VI will now read from
multiple channels. Often it easiest to
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
and WaveFormGraph.jpg)
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
converter for each channel.
For the large majority of applications, the small delay
between channels is negligible.
Jared T.
Attachments:
ReadtoGraph.JPG ‏21 KB
ChannelConfig.JPG ‏288 KB
WaveFromChart.JPG ‏61 KB

Getting Started with Swept Sine (DAQmx) Multiple Response Signals

Hi,
I've been using the modified version of the Getting started with swept sine.vi for multiple response signals
https://decibel.ni.com/content/docs/DOC-24474. Program fully suitable.
However, I am facing with three issues :
1) The edits are highly non user friendly (horrible for 6 multi-channel already), and quite long to perform.
2) Would there be a way using for loops to have a more compact and flexible way to use FRF? (Calling 6 times the same program in a similar structure does not quite seem like a smart move yet I'm relatively novice in LabVIEW).
3) Be able to set the number of channels somewhere in the software, and automatically have the software to be able to cope with this? (aka if 20 multichannels are needed, no need to modify the code?)
It's probably going to be a lot of work to get there, all I'm asking for you guys is to point me in the right direction and suggestions,
Cheers,
Kentmey
Kentmey

duplicate post, continue here…
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

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.
Having looked at forum and Labview examples i tried to make an initail VI but i am not sure if the setup i made needs any modification to serve my purpose.I am fairly new to Labview software.
All i want is
1.To acquire conteneously current and voltage
2.Display current and voltage individually on the graph.
3.Perform some basic calculations like MAXIMUM,MINIMUM and AVERAGE values of voltage and current.
4.Log the data into excel file
I have attached the VI i made so far.i need abit of advice if i am moving in the right direction or not.
Thank You for having a look at my question.
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.
Yes, you are logging directly to a TDMS file. This is definately the best route for data logging from a DAQ. The currents and voltages will show up as different channels in the same group.
To add more channels, just add them to your DAQmx task. The logging will handle it with no issue. Your calculations will also a little work to add the extra channels. Same for the graphs, since you are using seperate charts.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Multiple channels acquisition and Number of samples per channel

Hi,
I'm a new labview user and I need some help in trasposing an old traditional NI-DAQ acquisition software in a NI-DAQ-mx one.
I followed the tutorial (#4342) but I found a problem with Analogue 2D DBL Multiple Channels Multiple Samples DAQmx Read Vi.
I'm trying to acquire 8 voltage signals from a NI-USB-6341 device. When the Number Of Samples Per Channel I set is below the number of channels (8), the software acquires only a number of channels equal to the number of samples per channel I set.
Is that a normal behaviour?
Thank you
Daniele

This is my code. The problem is the same with or without the code for the scan backlog indexing.
Tomorrow I will try with the code from the example.
Thank you
Daniele
Attachments:
acq code.jpg ‏119 KB

Steps to create a VI to read multiple channels

This is the first time I've used LabView. I want to create a VI to be able to read viltages from multiple channels and output the value of each channel to individual numeric indicators in the VI. I know how to read a single channel and I've created a task in DAQmax with multiple channels but how would I put that into a VI that will do what I need.
Thanks,
Albert

Assuming you are using the DAQ Assistant and getting one sample per scan, then you just use the Split Signal and wire the outputs to your indicators.
Message Edited by Dennis Knutson on 04-30-2007 09:49 PM
Attachments:
Split Signals.PNG ‏4 KB

Multiple channel AI measurement in the same module with synchronised AO

I am using NI -9172 for measurment. I am trying to mesure two AI voltage signals on the same module (NI9215).A sinosoidal analog input voltage is generated using NI 9263. The AI and AO are synchronised using Ai start trigger signal from NI 9263( AO). While I can measure an AI signal using the same module, it does not show any measurement signal when I try to modify the VI program for multiple channel measurment. I don't see any kind of error in the program. ( At least the program does not show any kind of errors) Can anyone please tell me what my problems are? I have attached the VI below.
Attachments:
modified Magnetstriction.vi ‏96 KB

Hi
When you say it is working for one channel do you mean that if you enter either one of the inputs among Magenetic Flux or Strain you can see both the input and the output signals? I noticed that you have two DAQmx Create Virtual Channel VIs. They are connected to each ohter and to the same array. This essentially translates into the signal being shown in one graph. For learning more on using multichannel programming please refer to Multi Device Sunch--Shared External Convert Clock.vi. Hope this helps.
Ipshita C.
National Instruments
Applications Engineer

Sme device multiple channel different bridge

Hi
I am using NI 9219
I have input from three different channel configured in different bridge mode with internal excitation.
I am able to acquire signal from each channel individually,
But I am not able to acquire data from all channel from a single vi an display them in a single graph.
Please help ASAP
Thnx
Ravinedr

Hi Revinedr,
It sounds like you are probably trying to run multiple analog input tasks at the same time. You can only run one of these tasks at a time. You can set up your task to include multiple channels with different bridge configurations, just set them up sequentially with the Create Virtual Channel VI.
Message Edited by PBear on 06-20-2008 12:53 PM
PBear
NI RF
Attachments:
multiplechannelbridges.gif ‏5 KB

How to create multiple channels in DAQmx

Hello ,
I created an application based from this example program, MultiFunctionSyncAIAO_DigStart (from VCNet).
I added another input and output channels, which later on I plan to add trigger features between
the two signals ( could be both inputs, both outputs or a combination of I/O). For now,
I am concentrating in the creation/ setup of multiple signals.
I desperately created multiple channels by converting the variables to array. Obviously, this
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Unfortunately, I do not know how to use it. ( clueless )
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A
DAQTestingDlg.cpp (14 kb)

Hi Patrick
To convert the code using multi I/Os, I included the multi reader/ writer header files.
Plus, those variables that require updating of data type are now in CNiReal64Matrix.
I also omitted the SineWave(), which i think I cannot use it with the CNiReal64Matrix data type.
But, I wonder why is that I have no significant output based from the amplitude. I hooked it up
with the scope but saw nothing. Aside from the changes that I mentioned, I didnt do anything
drastic. To make the conversion fuss-free using the same example, i retained the UI and converted
the single functions to the multi functions. I will add the control for additional I/Os later on.
Please point it to me why the code has no output after the m_outputTask->Start(). I really can't get the output
portion working it. I browsed through the different voltage analog output for VC++ but all examples
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Btw, is there a way that i can use a sine wave or similar function to display a nicer waveform?
Thanks a bunch for all the help,
A
Attachments:
MultiFunctionSyncAIAO_DigStartDlg1.cpp ‏15 KB

Save multiple channels to binary?

I am trying to save multiple channels of analog signals measured using DAQ express. I want to save the waveforms to binary and be able to read them back to re-create the waveforms at a later time. I have tried writing the waveforms to binary as dynamic data and as arrays. Neither seems to work. I am not sure if my problem is how I am saving/writing the data or how I am trying to read it back. What is the best form to use to write the data and how should I read it back?

Hi VCUBME,
LabVIEW is shipping with some good examples that show how to store your data effectively using binary files or datalog files. Please try the "Write Binary File.vi" with the "Read Binary File.vi" for an exaple of storing simple arrays. If you need to store more complex data as for example clusters, then refer to the "Write Datalog File Example.vi" and "Read Datalog File Example.vi".
Have fun!
- Philip Courtois, Thinkbot Solutions

Reading multiple channels for multiple graphs

Hey I am fairly new to Labview and am using it just temorarily. My project is to take in readings from a Gaussometer (X,Y, and Z axis) and graph them in read time. The Gaussometer outputs a DC Voltage equal to the gauss of the magnetic field. The X,Y,Z all come in on three differnet channels. Connected to a NI USB-6009
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Displaying real-time data using gui meter from multiple channels.

I am using DAQ USB-6009 for my assignment. Part of my task is to display real-data from multiple channels in the form of gui meters. eg. irradiance and voltage...
I used a split signal to separate the signals from different channels coming out of the data output terminal of the DAQ assistant. The problem is that I do not know which vi to connect in between the split signal and the gui meter. I am looking for one vi that is capable of handling signals (measurement) and outputting the data to the gui meters simultaneously and individually based on the channel they are coming from.

Thnx for your tip, Dennis.
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I noticed that the needle on my gui meter will only "appears" to be responding to every changes to its input when I have set it to run continuously and the only way to stop it is via abortion which might leave the resources (eg. external hardware) in unknown state. Is there any safer and workable ways to organise the VIs using while loop?
I have placed my DAQ assistant, write to measurement file (vi), add function, split signal and gui meters all in 1 single while loop.
    DAQ-------> write to measurement file
             |
             |                                                                    |--------------------------------> add function----> gui meters
             ---------------------------------------------> split signals ---|--------------------------------> add function----> gui meters
                                                                                  |--------------------------------> add function----> gui meters
If I do the following steps,
1. press run continuously to start the VI
2. click the same button to disable continuous run when the VI has completed its task.
3. click the stop button in the front panel to stop the while loop
Does doing these steps ensure that I will not leave resources in unknown state? Is it a safer way to stop a VI which is running continuously?
Pardon me for I am new to LabView. Even though, I have read the user's
manual and tried out all the execises, there are some concepts that I
need clarification on and mistakes that I need to discover through more hands-on.

LabVIEW and Elvis II+ simultaneous multiple NSRE signal measurements

How many voltages having not common ground can be measured at a same time? I have learned how to measure one floating ground (NSRE) voltage and common ground voltages (SRE) at a same time. I do NSRE measurement this way: higher potential of measured signal is linked to "ai0", lower potential linked to "aisense". Can I measure multiple NSRE signals simultaneously?

Hello Labview elvis daq
You can measure multiple NSRE simultaneously, just connect your higher potencials to the aiX and all the lower potentials to the aisense.The maximun number of channels will be equal to the number of Analog inputs that your device has.
Warm regards,
Martin

Generating Multiple Modulated Signals

I was a bit surprised I didn't see this on the forums, though I am new to the RF gear. What I would like to do is generate two modulated signals, such as 802.15, on two different frequencies. I am already able to create the signals individually using the modulation toolkit. I am using a PXI-5671 RFSG. I have found how to generate with interferance two CW tones in the examples, but do not see how to generate the two modulated tones. I also need to be able to set one of the modulated signals to a lower power than then other. I am trying to test adjacent channel interferance with modulated signals. Any thoughts?
Troy

Hi Troy,
There are a few tricks you can play here but
they are completely independent of hardware and more on signal
processing. Basically you need to write both waveforms at the same time
with different frequency offset.
1) Frequency Shift. Assume you
have two completelly independent baseband signals s1[n] and s2[n]. Each
one should be the same lenght (time duration).
One of them will
be transmitted at Fc and the other one at Fc + df. s1[n] remains
unchanged and s2[n] will be shifted by df using the following VI:
The
trick here is to make sure that your sample rate is high enough to
support the shifting, otherwise you will be aliasing. If you create
your waveforms with Modulation Toolkit make sure they have enough
samples per symbol.
Finally you need to sum all signals s[n] = s1[n] + s2[n].
2)
Apply different Powers. Before you add the signals, you only need to
scale the data correctly. To do this, I recommend to normalize both
waveforms. This is s1[n]/max(sqrt(|s1[n]|). Thenscale the smaller power
one. Finally, you will add them together.
Here is a spectrum of the composed signal:
I have attached
an example to do this using 802.15 signals with a few modifications: I
am not normalizing data but applying headroom to each signal and I
hardcoded the number of samples per symbol so the maximum frequency
offset is about 12 MHz. Should be helpful to get started.
Message Edited by Yardov on 10-17-2008 06:05 PM
Gerardo O.
RF Systems Engineering
National Instruments
Attachments:
frequency shift.jpg ‏9 KB
Generation Multiple Channels.zip ‏32 KB
spectrum.jpg ‏79 KB

How do I read multiple channels at one time using labview with the Fluke Hydra Data Bucket 2620a using serial port?

I need to take a reading of 15 channels about once a second. I can read one value at a time using the monitor function on the read values.vi driver, but this takes forever to read all the channels.

I don't have this instrument but I took a look at the instrument driver and it appears that you can only configure one channel at a time to read from. You might want to take a look at the command set for this instrument and see if it allows for configuration of multiple channels. It could be that the instrument driver just doesn't have that built in.
J.R. Allen

FP-AI-110 Multiple Channels - Signal Degredation

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