Thanks Rob, yes I am using a 54825A which is supported by that driver, but the Configure Multiple Channels function is only valid for the 54845A. Found the work around though, in the Action-Status subPalette is a function called hp548xx Actn On Off.vi
I used this to force three channels to be enabled, and was then able to configure them and retrieve the waveforms from all three channels.
Thanx for the reply, weird that the one function is limited to a single model while the rest of the functions are valid for the entire family, but at least there is a simple work-around.
Thanks again
lmd2
Lawrence M. David Jr.
Certified LabVIEW Architect
cell: 516.819.9711
http://www.aleconsultants.com
[email protected]

Similar Messages

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

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

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

How to use multiple channels with one remoteObject .

hi,
I have an application which is accessed through HPPS some
times , also it can be access on server with http service.
so I want to know how to configure config files or add
runtime channels which will support either channel depending on
the server it is accessed over.
Is there any one who can help me to solve this...i need it
soon.
thank you...

Hi,
Please visit the URL below for details on adding channel sets
at runtime. Add multiple channels to the channel set so that the
fall back mechanism works.
http://livedocs.adobe.com/blazeds/1/blazeds_devguide/runtimeconfig_5.html#194376
Hope this helps.

What is the recommended way to do multiple channel, single point sampling for control with an NI PCI-6255 in RLP?

Hello,
I am writing a driver for the M-series NI PCI-6255 for QNX. I have downloaded the MHDDK and have all the examples working. I have also enhanced the examples to do interrupt handling (e.g. on AI_FIFO interrupt or DMA Ring Buffer interrupt). My ultimate goal is to write a driver that I can use for closed-loop control at 500 Hz using all 80 channels of the NI PCI-6255. I may also need to synchronize each scan with a NI PCIe-7841R card for which I've already written a driver. I want an interrupt-driven solution (be it programmed I/O on an interrupt or DMA that generates an interrupt) so that the CPU is available to other threads while the 80 analog inputs are being read (since it takes quite a while). I also want to minimize the number of interrupts. Basically, I will need to collect one sample from all 80 channels every 2 milliseconds.
There are many different options available to do so, but what is the recommended technique for the NI PCI-6255 card? I tried using the AI FIFO interrupt without DMA, but it seems to interrupt as soon as any data is in the AI FIFO (i.e. not empty condition), rather than when all 80 channels are in the FIFO, so more interrupts are generated than necessary. I tried using DMA in Ring Buffer mode to collect a single sample of 80 channels and interrupting on the DMA Ring Buffer interrupt, which appears to work better except that this technique runs into problems if I cannot copy all the data out of the DMA buffer before the next AI scan begins (because the DMA will start overwriting the buffer as it is in ring buffer mode). If the DMA is not in ring buffer mode or I make the ring buffer larger than one 80-channel sample then I don't have a way to generate an interrupt when one sample has been acquired (which I need, because I'm doing control).
I saw something in the documentation about a DMA Continue mode in which it looks like you can switch between two different buffers (by programming the Base Count/Address with a different address than the current address) automatically and thereby double-buffer the DMA but there is no real documentation or examples on this capability. However, I think it would work better than the Ring Buffer because I could interrupt on the DMA CONT flag presumably and be copying data out of one buffer while it is filling the other buffer.
Another option would be DMA chaining, but again, I cannot find any information on these features specific to the NI DAQs.
I tried interrupting on AI STOP figuring that I could get a single interrupt for each scan, but that doesn't appear to work as expected.
I know that DAQmx on Windows has the ability to do such single sample, multiple channel tasks at a fixed rate so the hardware must support it.
Any suggestions would be appreciated.
Thanks.
Daniel Madill

Hello,
The interrupt that will happen nearest the times that you need is the AI_Start_Interrupt in the Interrupt_A group. This interrupt will occur with each sample clock. By the second time this interrupt fires, the AI FIFO should have the samples from the first conversion. If it is easier to use programmed IO, you can read the samples out of the FIFO until you get all 80.
Additionally, you can set the DMA to send samples as soon as the FIFO is no longer empty...instead of waiting for half full or full. This change will reduce latency for your control loop. You can set AI_FIFO_Mode in AI_Mode_3_Register to 0. By the second time this interrupt fires, you should be able to check how much data is in the DMA ring buffer and read the 80 samples when they are available. You can make the ring buffer larger than 80 samples if you see data getting overwritten.
There is no interrupt associated with 80 samples being available in the FIFO or 80 samples being available/transferred by DMA to the host. X Series has much more flexibility with these interrupts.
I hope this helps!
Steven T.

How would you apply different calibrations to multiple channels

I'm attempting to apply calibration data to multiple channels. The calibrations could have been done at different times for different channels and could be using different fits. I think I have a solution for just applying the calibration information to one channel. I'm posting the solution for one channel in this post. In the next post I will include the multi-channel problem I'm working on. I had to add txt onto the initial file in order to post this.
Thanks in advance.
Solved!
Go to Solution.
Attachments:
Apply Calibration One Channel.vi ‏138 KB
Initial.txt ‏1 KB

Thanks for the links John. I just logged on to post my working solution so I haven’t had a chance to look at them yet.
I’ve been working on this problem and have come up with the below attachment. I believe the logic is correct, but do not know if this is the most efficient way of doing this. I start by reading the calibration information in my ini file for only the channels that I am collecting data for. This is accomplished by the case structure enclosed in the for loop. The calibration values are stored as variables so I don’t have to read them with each data point I collect. I then start the data collection within my while loop. As I collect the data I pass it through a for loop where I apply the calibration curve to it and pull the calibration variables from the 2nd case structure. I’m using a for loop for this so I can index the wave files and apply the correct calibration information to each one. The channels and sections will be inputs to this vi from the choose channel vi.
John I don’t know if this is better or worse than what you are suggesting. I will read the links you sent me.
Does anybody have any comments on what I’ve put together?
Thanks, Eric
Attachments:
Acquire and Transform Data.vi ‏209 KB

Counter to measure frequency with multiple channels (Analog In/Out) in one vi

Hi,
I am using DAQ 6062E. I have multiple channels: an Analog In, Analog Out, Count Edges, and Count Frequencies. Without Count Frequency, the program works fine, I have defined a Sample Clock for each channel and then a common sampling rate. When I add Count frequency channel, I am not able anymore to use Sample Clock, since I get an error that Sample Clock can not be used, and if I change the Sample clock of the Count frequency to Implicit, then I can not connect different channels with a same sampling rate. In the attached file, if the Count Frequency is not connected to any Sample clock and sampling rate, the program works, but now I can not run the program for more than 5-10 Hz sampling rate, otherwise I get the error: 209802 “occurred at DAQmx wait for next sample clock, slow down the sample clock”. Does anybody know how to fix this problem?
Thanks a lot,
Azadeh
Attachments:
multiple channel.jpg ‏117 KB

Hi Otis,
Thanks for looking at the problem. I ran just two counters in a same vi. I was not able to use the Sample Clock since I needed to define an external sample clock source. The vi is attached. I could run this vi fast (200Hz). So, I am not sure why when two counters are combined with AI/AO the rate is very slow. I have attached three vi(s). Just two counters, AI/AO/1 counter, and AI/AO/2 Counters vis. I am able to run the vis in 200 Hz except the vi with AI/AO/2 counters (maximum sampling rate 20Hz). I appreciate if you can look at it if I am missing something.
Thanks,
Azadeh
Attachments:
AI_AO_2 Counter.vi ‏153 KB
2 Counter.vi ‏61 KB
AI_AO_1 counter.vi ‏138 KB

Multiple channel data with different time stamp logging

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

Multiple channel sampling and write file

Hei,
I wrote a interface which is supposed to allow me to plot multiple channel and write all those datas in a file ; The problem is that :
1- not all the curves are plot in my graph (in fact just one is ploted).
2- At the same time it write in a file but after some times it stoped due to an error : buffer size...related to the offset.
I have attached the vi, I don't understand exactly where those problems are comming from and how to solve them easily.
Thanks for the help
P.
Attachments:
project.vi ‏207 KB

Hi thanks those tips. In fact I had solved those problems mentionned above ; I have alomst finish my interface except that I am trying to write all my datas in a file , in column (all channels) and create a first column at the time (maybe from the sampling time). The problem is that I don't know the output fomat of the "analog 2D DBL" vi and it seems that my way of writing datas time step per time are not right. have you already see this kind of used (analog 2D DBL)? I am using a PCI-6229, and DAQmx 7.3 Drivers
Thanks for your help
P.
Attachments:
project_acquisition.vi ‏338 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.
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

DAQmx multichannel read error. DAQmx believes there are multiple channels in my task.

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.
Jeff

Select multiple channels for one task - control and shift keys don't work

Hi,
Following advice from several other posts, I'm trying to select multiple physical channels from the dropdown list so that I can then use the "unflatten channel string" function later on. It looks like if I hold down either shift or cntrl I should be able to select multiple channels from the list, however, this doesn't work for me. I tried going into the "key navigations" property for the task channel control but it doesn't have any associations listed. Has anyone else come across this and found a fix? I have previously got around this by stating multiple channels with a colon (eg. ai1:3) but this doesn't work for the unflatten function.
Thanks,
Claire.
Solved!
Go to Solution.

Thanks for your reply Dennis, I see what you mean, unfortunately that doesn't solve my problem so I'm missing something else. I've attached my VIs. I expected that the output from the unflattenstring block would be an array of either the channel references or the names I had given them, and that therefore the "array size" in the 4th pane would be "9" (equal to the number of channels). Instead the output is a an "unnamed task#(some number)" when I look at it with a probe. Perhaps I'm misunderstanding how the task naming works?
THanks,
Claire.
Attachments:
Analog SW Trigger_v3.vi ‏33 KB
Cont Acq&Graph Voltage-Analog SW Trigger_cfjv3.vi ‏64 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

Agilent 548xx multiple channels

Similar Messages

Maybe you are looking for