LeCroy wavesurfer acquisition loop slowdown

Hello,
I am trying to acquire waveforms from a wavesurfer 434 over ethernet, and I am running into a problem where the scope triggers and then displays a "Processing... " message for multiple seconds before the scope is ready to trigger again. Timeout errors occur even though I am feeding the scope a 10Hz signal (the timeout is set to 10 seconds). This only happens once every 2-3 triggers, and I do not have any of the math, measure, or averaging features enabled on the scope, so I am not sure what is being processed. When I do not have the VI running, this does not occur in either normal or single trigger mode (ie, this does not occur if I manually press the "single" trigger button on the scope multiple times).
More information:
- I am using the example vi, "LeCroy Wave Series Acquire Waveform In Loop.vi," from the 3.2 revision of the driver package and have not modified it.
Thank you in advance for any tips/suggestions.
Attachments:
LeCroy Wave Series Acquire Waveform In Loop.vi ‏24 KB

Might want to check the following whitepapers:
Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications
http://www.ni.com/white-paper/2835/en/#toc4
Timing and Synchronization Features of NI-DAQmx
http://www.ni.com/white-paper/4322/en/

Similar Messages

Data acquisition loop with queue

What I would like to do is have a data acquisition loop that samples a load cell at 500Hz and have another loop that runs much slower to run a state machine and display some data in real time. The reason I want to sample the load cell so fast is to filter out some noise. Making producer/consumer loops with a queue kind of makes sense but I don't really care about all of the samples, I just want to be able to read a real time filtered signal at certain times. I looked at having just two parallel loops, one to acquire the data and the other to run a test and retrieve a real-time signal when I want but not sure how to pass data between the loops without using a queue. You can do it with local variables but you are at risk of a race condition. I hope this make sense. I am sure this is a simple problem I just don't know what direction to go. Thanks

Good Evening secr1973,
It sounds like you are on the right track. You already know about the producer/consumer architecture; this is almost always the first step to the separation that I think you are after.
The step that I think you are missing is a Case Structure around the enqueue element VI. You likely have some event or specific pattern that you are looking for in the input signal. You can have the output from this algorithm (likely a boolean) determine which case of the Case Structure to execute (Case 1: enqueue the element or Case 2: Do not enqueue the element).
This, of course, leads to processing being done in the producer loop, which is quite the opposite of what you are trying to accomplish with the producer/consumer architecture. You will have to decide if your processing is very simple or more complicated.
If it is easy/fast, you can likely get away with doing this processing in the producer loop. My guess is that your program falls under the category of do-it-all-in-the-producer loop because you are only acquiring at 500 Hz.
If the application requires faster acquisition rates or if the logic is going to require some processing, you may want to implement a double layer producer/consumer architecture. In this setup, you would pass all of the data from the DAQ producer to a second loop (using queue #1) that determines what to do with the data (to enqueue or not to enqueue...) and, if appropriate, write to a queue (queue #2) that the third loop can read. The third loop would be where your state machine executes.
If you have a quad core machine, each of these steps will execute on its own core. If not, you will have a little more thread swapping; not a huge concern in most cases. Here, we get into the art of programming more than the science.
In any event, I think you will be OK with a little processing for the enqueue or not algorithm in the producer loop.
Regards,
Charlie Piazza
Staff Product Support Engineer, RF
National Instruments

Lecroy Wavesurfer VICP and LXI/VXI11

Hello,
I want to connect a Lecroy Wavesurfer 454 to Labview.
First I used the VICP connection, and installed the VICP passport.
It does not work with NI MAX but it does with Lecroy Wavestudio.
Then I used the LXI/VXI-11 connection but Ni MAX does not detect my scope and Lecroy Wavestudio as well.
Further information, I don't use both softwares at the same time, the scope and the computer have ping responds.
I have updated the scope to the latest firmware 6.8.1.4 32 bit Firmware Upgrade.
The only way that Ni MAX reachs to connect to the scope it throug : TCPIP0::ipadress:1861OCKET. But then I have Time out error.
Thanks for help

Hello,
You have a few choices here. NI-MAX (more specifically, NI-VISA) stopped working with the VICP resource when NI introduced 64 bit LabVIEW support. (It stopped when the NI-VISA Interactive Tool GUI changed).
You can use an older version of NI-VISA (I do not recommend this method), or you can simply enable the VICP passport in NI-MAX and use LabVIEW to test the connection.
The VISA resource for the VICP interface will be: VICP::<IP address of scope>
I have attached a VI I wrote (pretty easy, but I added some images and comments to help with the scope side and resource names as well) to help test this out. (I have it in LabVIEW versions 2009, 2010, and 2011) I am providing the 2011 version. Let me know if you need one of the others.
The VICP connection uses the custom port but with the resource you used (that specified the port), the VICP passport is not being utilized by NI-VISA so you may get responses to some legacy 488 commands but that is the extent of it. (i.e. *IDN? may work, but C1:VDIV 1.0 would not).
I hope this helps!
Regards,
Leonard Brown
Applications Engineer
Teledyne LeCroy
1-800-553-2769
Attachments:
LV_2011Test__Scope_Connection_no_driver.vi ‏36 KB

Lecroy Wavesurfer 454

hello everibody.
i am new in labview and i am tryng to use the Lecroy Wavesurfer 454 with labview 8.6.
unluckly i am not able to use the example vi in the driver file.
i run the example finder for Wavesurferand, then run lecroy wave series acquire waveform.VI and correctly setted the tcpip instruction with TCPIP::192.168.219.53::INSTR and run the VI.
the error that i received is:
VISAHex 0xBFFF0011) Insufficient location information or the device or resources is not present in the system
even if with the ping 192.168.219.53 command works correctly.
Solved!
Go to Solution.

Hello,
To solve your problem, I invite you to check those links :
VISA: (Hex 0xBFFF0011) Insufficient location information or the device or resource is not present in...
GPIB Installation/Configuration Troubleshooter
Regards,
Steve M.
National Instruments France
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Acquiring 4 traces (simultaniously) from Lecroy Wavesurfer with LabView 7.1

Hello everyone
I am actually using Labview 7.1 to acquire the data from my Wavesurfer 454. I can do it for one trace. It look like this “armed” the scope then when it gets the trigger, Labview collects the data.
The problem is I would like to collect the 4 traces after only one trigger… is it possible? Could you please explain me how to do that?
Because if I use a loop and change each time the channel to acquire, I need 4 trigger... although I would like to acquire them from the same trigger...
Many many thanks!
Sebastien

Hello,
Alan from LeCroy Tech Support here...
I recommend using the "lcwave" driver that's on NI's Instrument driver network. It includes an example for reading out multiple waveforms (2 channels)that can easily be extended to readout all 4 channels. To find the driver quickly, go to http://www.lecroy.com/tm/Library/Software/LabView/LabViewDrivers.asp?menuid=8 where you will find a link to the driver on NI's website. Let me know if you have any problems using the example.
Best Regards,
Alan
Alan Blankman, Technical Product Marketing Manager and LabVIEW Developer
LeCroy Corporation
800-553-2769 x 4412
http://www.lecroy.com
[email protected]

How to control the acquisition loop?

Hello,
I have the following structure in my code, in the acquisition below, I would like to set some sort of a trigger or condition to control when to start reading. Without the condition,It works fine, But it reads all the time as long as my thread is on. In traditional drivers, I had DAQ-DB-HalfReady flag to control when to start reading. How could I accomplish the same concept here?
Thanks
while(Thread is ON)
{ GetNIRawData()....}
int GetNIRawData()
   if( Condition here){
DAQmxReadAnalogBinary16(taskHandle1,ai0:ai3,....) // Read Analog
DAQmxReadCounterU32(taskHandle2, 1000,......) // Read Counter1
DAQmxReadCounterU32(taskHandle3, 1000,......) // Read Counter2
        } // end condition here
Note if I use the following structure, I get error code -200019,
int GetNIRawData()
int status = DAQmxReadAnalogBinary16(taskHandle1,ai0:ai3,....) // Read Analog
if(Status==0) // as my condition
    DAQmxReadCounterU32(taskHandle2, 1000,......) // Read Counter1
     DAQmxReadCounterU32(taskHandle3, 1000,......) // Read Counter2

Hi softwareguy,
You could trigger analog input and counter tasks off of your
encoder. The example DAQmx
– Event Counting on Multiple Counters with Digital Start Trigger shows how
you can set a digital start trigger for two counter tasks. For your
application, wire your encoder to a PFI line and select that line as your
trigger. This method will not require you to read or check the motor state
since it won’t begin reading until the encoder starts moving.
Alternatively, if you are using a DAQmx Task to drive your
motor, you can use the DAQmxIsTaskDone function to query the execution status
of that task. The Boolean variable isTaskDone will return true if the task has completed
or is not currently executing and false otherwise. Below is a screen shot of
the NI-DAQmx C Reference Help (Start »
Programs » National Instruments » NI-DAQmx C Reference Help) on this
function.
Please post back if you have any questions. Have a great day!
Message Edited by ryan_d on 12-03-2007 02:43 PM
Ryan D.
District Sales Manager for Boston & Northern New England
National Instruments
Attachments:
DAQmxIsTaskDone.png ‏35 KB

PXI: NI 5600, data lost or stored if the loop time of processing is slow than the acquisition.

I want to know what occurs exactly at the time of L acquisition and the processing data acquired with Ni 5600. When J write my programme of processing of data in Labview, if the loop time of processing of data is slow than the acquisition, I want to know if PXI put the data in a buffer or then the data are lost.
J wait your answer impatiently. You can tell me the documentation were can i read to see the answer.
Anybody can help me.

hi abidi,
First, let me tell you how buffered acquisiton works.
If you are using Daq mx for continous acquisition, Labview will autoselect the size of buffer depending on the sampling rate specified.
In sample clock.vi, select sample mode as "continous samples".
Now, Labview will determine the loop speed for reading data that is written into the AI buffer and hence run necssary number of AI read loops to retrieve data from the buffer every second.
this loop speed can also be set by specifying "number of samples per channel" in AI read.vi.
If you leave this value at default ( -1) labview will function as explained above
This can also be set by user ,for example, if your sampling rate is 1000 saples per sec and number of samples per channel is 200, the AI Read functions is performed 5 times in a second.
read this link to get to know about cyclic buffers and continous acquisition.
http://zone.ni.com/devzone/conceptd.nsf/webmain/F2DDCBAD754C687C86256802007B8514
You tell that you are performing some processing on acquired data.
Now, your prgram has to allocate adequate process time for acquiring,retriving data from buffer and then processing it.
the time allocated for processing data depends on the kind of mathematical conversions involved. Nevertheless it is an overhead on the acquisition loop.
this may result in overflow of buffer and data being overwrittien in buffer which results in data loss. An eror message might also pop up to warn that this has happened.
so if your application permits, here's what you can do to avoid this problem
First acquire data and save it on system in ascii or binary fromat.
later retrieve this data file and perform processing /analysis on it.
if you have any further doubts, plz tell.
regards,
Devchander M

Inconsistent Parallel Loop Performance

My original question was can traditional DAQ devices run in parallel loops? I have some extensive data processing and additional automation that would be a lot easier to do in parallel with an acquisition loop rather than cram it all into the acquisition's while loop. As I was building an example VI, I discovered the answer seems to be "sometimes".
I am working on a calibration rig for hot wire anemometers. It requires pressure values to be read into a PCI-4351 (traditional DAQ) for the duration of the calibration and record wire voltages to a PCI-6110 (DAQmx device) only when the pressure values have settled (i.e. the stream velocity is constant). Inevitably, both devices will be polling data simultaneously at some point.
It seems that the 4351 would transfer its data to a parallel loop, but not when 6110 was running and vice versa - and sometimes the buttons to stop the loops wouldn't work. Will traditional DAQ and DAQmx devices not perform parallel tasks simultaneously?
The attached VI might clear up the parallel structures I'm talking about.
Andrew
Andrew
Attachments:
ParallelLoopsExample.vi ‏32 KB

Altenbach,
You pointed me a good direction - I wasn't familiar with action engines until you mentioned them, but after some reading (namely Ben's AE nugget), you have me convinced (although not entirely sure on how to proceed) so here come the questions!
1. I tried to use Ben's running average example as a template - what should the cases inside my AE be? Right now they're "initialize", "acquire", and "close". However, I have to pass a value from initialize to acquire to close - so as is, the VI won't run.
2. Ben had his AE in a loop to add data to the array and in another loop to perform the running average calculation. Since you end up with two of the same thing in your BD, how is this better than creating a local variable?
3. Best practice? I'm pulling values from several channels - should I isolate each channel an put it into its own SR within the AE or keep the data together and have a single SR for the 2D array?
I don't expect anybody to have the 4351 drivers installed - so the what you're probably seeing as three "?" VIs in the "Initialize" panel are the VIs needed to initialize the device (sampling rate, number of scans, etc.), the single "?" in "Acquire" reads the data and the two in "Close" end the acquisition.
Brad,
Thanks for the tip - I'll keep that in mind when I'm implementing the 6110 acquisition into my code
Andrew
Attachments:
InputAE.vi ‏20 KB

How do I move data from a DAQ into and out of loops and structures?

I have a set of RTD probes set up to read data into LabView through a DAQ. This block of code is in a while loop
that executes alongside of several other loops simultaneously. I need to use the data from the RTD probes in other
loops and case structures specifically for logic tests.
The problem is that I can't seem to bring the dynamic data out of the DAQ containing while loop or into the other structures.
Any ideas?
I have had some success with using multiple DAQs and stopping all others while I need the data inside of a case structure.
Is there a way to reference data from a DAQ or to run multiple DAQs that read the same data from the same channels without getting a "Task in use error"?
Thanks,
-David

Search the forums for Prodcuer/consumer architecture.
This uses queues to pass data from the producer loop (such as your data acquisition loop) to other "consumer" loops. These are the other loops where you want to use the data.
You won't be able to use multiple DAQ Read functions at the same time. As you've seen you get error -50103 about the resources already being in use.

Faster loop rates

Hello. I am looking for help increasing the execution speed of the attached VIs. The equipment is a PXIe-8135 controller running LVRT, PXIe-6368 DAQ, and PXIe-7966R FPGA. I am using a hardware timed, single point data acquisition loop that will eventually implement some sort of feedback control, and I need the highest possible rate (ideally above 100 kHz). Leaving out the FPGA, I was able to run the loop at 200 kHz on the real time PXI target. However, incorporating the calls to the FPGA has cut that down to about 60-70 kHz. (The FPGA is needed because multiple channels will be added and the computation might get more involved than the RT processor can handle quickly.) Here are some specific questions.
1. Data conversion. Now I am reading data from the DAQ as a floating point double, but then I need to convert it to send data to the FPGA. I am not sure if converting to fixed point rather than single is more efficient? Or should I try reading raw I16 data from the DAQ? I believe this creates an array of integers, so it might be slower?
2. Data logging. If I turn on data logging, the rate is drastically reduced. Is using the built-in TDMS logging from the DAQmx pallete not the best option? This usually works better for me than a parallel data logging loop with local variables.
3. FPGA polling. Would another method be better? For single point transfers, I didn't think DMA FIFOs are the right approach. I did try the IRQ interrupt method, and it was slightly slower.
I really appreciate any suggestions. Any little tweak will help at this point. Thanks for your help!
Jeff
Attachments:
fpgaVI.png ‏11 KB
targetVI.png ‏25 KB

You are going the expensive route! Are you using any of the IO on that FlexRIO board? If not, you are totally going in the wrong direction with this.
Why not just go with something like the PXI-7854R, which can handle your analog inputs and outputs. And it is cheaper than that DAQ card. Then all of your acquisition and control logic can happen on the FPGA. You just have to use a DMA to send the data to the RT system for logging.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Choice of design pattern for data acquisition system

Hello all
I have a trouble about selecting the suitable design pattern / architecture for a data acquisition system.
Here is the details of the desired system:
There is data acquisition hardware and I need to use it by observing parameters on User interface.
the data acquisiton period, channel list to scan should be chosen on User interface. Besides, there are many user interface interactions. e.g. if user selects a channel to add scanlist, then I need to enable and make visible some other parts on user interface.
When user completes the channel selection, then he will press the button to start data acquisition. Then I also need to show the scanned values on a graph in real time and log them in txt file.
I know that I cannot use producer consumer pattern here. because the data acquisition loop should wait for parameters to scan channels. and it works in a given period by user. so the user interface loop performs higher rate then consumer loop (data acquisition loop). it means queue will be bigger bigger. if I use notifier it will loss some data come from user interface.
is there any idea about that ? is there any suitable design pattern for this case ?
Thanks in advance
best regards
Veli BAYAR
Embedded Systems Software and Hardware Engineer
"You live in a graphical world. Why not program in one?"
Solved!
Go to Solution.

johnsold wrote:
Veli,
I recommend the Producer/Consumer model with some modifications.
You might need three loops. I cannot tell for sure from your brief description.
The User Interface loop responds to the user inputs for configuration and start/stop of acquisition. The parameters and commands are passed to the Data Acquisition loop via a queue. In this loop is a state machine which has Idle, Configuration, Acquisition, and Shutdown states (and perhaps others). The data is sent to the Processing loop via a different queue. The Processing loop performs any data processing, displays the data to the user, and saves it to file. A notifier can be used to send the Stop or shutdown command from the User Interface loop to the other loops. If the amount of processing is minimal and the file write times are not too long, the Processing loop functions might be able to occur in the Timeout case of the UI loop Event structure. This simplifies things somewhat but is not as flexible when changes need to be made.
I am not sure that a Design Pattern for this exact setup exists but it is basically a combination of the Producer/Consumer (Events) and Producer/Consumer (Data) Design Patterns.
Lynn
Check out this thread: http://forums.ni.com/t5/LabVIEW/Multiple-poll-case-structures-to-event-help/td-p/2551309
There are discussions there about a 3-loop architecture that may help you.
Jeff
Jeffrey Zola

While loop halted

Hello Folk,
I am developing an application which acquires data at 1 ms and store it to TDMS file. I have two seperate loop for acquisition and data writing. I set starting of acquisition on trigger pulse so while loop halts untill my system is triggered and resume on trigger pulse. Now that writing into TDMS file is slower than acquisition, I queue acquired data and dequeue it in another loop.
Here my problem comes,
As of faster acquisiton, for 600 seconds data acquisition my file is written with only 195 seconds data. The rest of data is in queue. As soon as the stop trigger comes my acquisition loop halts and with it my writing loop halts too. It is not being possible for me to write another 405 seconds data in to file though my program is running.
Is there any way that my writing loop never halts? I havenot configure anything for my writing loop to halt however the dequeue reference of my writing loop is the same as queue reference of acquistion loop.
Your help will be truly appreciated.
Thank you,
CLAD
Passionate for LabVIEW

Hello,
I designed this code for RT and that is why I used timed loop and dint put any condition to stop the loop. I m not sure am I right or not on this.
Answers to your other questions are below,
Only latest packages are missing and I removed that sequence.
Can you please put some more sense into me for well designed RT code??
One more thing I would like to ask is there any way to write the data faster,? I meant as soon as the data queued up it should be written into file.
Norbert_B wrote:
Several things to consider:
- Without seeing the complete code (VI), we can only guess about things
- You use nested case structures which rely on shared variables to enqueue data. I doubt that you enqueue the amount of data you *think* you enqueue
- Have you ever checked the iterators for the loops? For the enqueuer, you should create a custom iterator to count the enqueues you are performing (seems that you are already counting this, but not "using" it)
- Which "packages" are "missing"? Only the latest? Some "in between"?
- Why do you use a timed loop as producer?
- Why are both loops running without the option to stop? Is that a program running on RT, please learn how to desing code for RT.... (as your code is obviously not designed for RT)
- Why all those sequence structures? Please remove them
All in all, i currently assume that the VI is working "perfect" as it only does what your code tells it to do. If that is the same that you *want* it to do.....is the question.
Norbert
Norbert_B wrote:
Several things to consider:
- Without seeing the complete code (VI), we can only guess about things
- You use nested case structures which rely on shared variables to enqueue data. I doubt that you enqueue the amount of data you *think* you enqueue
- Have you ever checked the iterators for the loops? For the enqueuer, you should create a custom iterator to count the enqueues you are performing (seems that you are already counting this, but not "using" it)
- Which "packages" are "missing"? Only the latest? Some "in between"?
- Why do you use a timed loop as producer?
- Why are both loops running without the option to stop? Is that a program running on RT, please learn how to desing code for RT.... (as your code is obviously not designed for RT)
- Why all those sequence structures? Please remove them
All in all, i currently assume that the VI is working "perfect" as it only does what your code tells it to do. If that is the same that you *want* it to do.....is the question.
Norbert
Thanks for your concern
CLAD
Passionate for LabVIEW

Writing data from two different acquisition rates into one file

Hi,
I'm using a compactRIO, and I have an anemometer outputting data at 4Hz to the serial port on the controller, and I am using a 9237 module to read strain from two channels at 40Hz. I would like to record all this data in one file, but I'm unsure how to have the data points match up with respect to time since they are read at different rates. Basically I have 10 strain data points for every one anemometer data point, but that one data point needs to somehow be associated with the other 10 read in the same amount of time. It would be okay to "extend" the slower data to the 10 strain points, and likewise to the next ten when the anemometer refreshes its values.
Thanks for any input!
Andrew

Check out the Queue multi-plexer vi from the examples. C:\Program Files\National Instruments\LabVIEW 2009\examples\general\queue.llb\Queue Multiplexer.vi
If each data acquisition loop enqueues data to one file writing loop the data is writen in order. Queues are really a good way to multiplex data sources
Message Edited by Jeff Bohrer on 01-29-2010 09:44 AM
Jeff

Threads in while loop with two data acq loops

Good day, I am using two while loops to perform data acquisition from two different pieces of hardware inside a "main" while loop - a total of three while loops. I want each of the data acq loops to run as fast as possible. With this model will each data acq loop run in a separate thread or will they be running in the same thread because they are both inside the "main" while loop.
I'm not getting the performance I would like and I'm looking at ways to optimize the execution.
Thanks
John

I would have a loop for each of you data acquisition tasks and at least one, possibly two additional loops that will write your data to file. Let the acquisition loops collect the data as quickly as possible and simply queue it off for further processing. When these loops are in parallel LabVIEW will run them on separate threads. In addition you could have a separate loop with an event structure that could handle you UI interaction. This loop could control the overall application with respect to starting and stopping the tasks, etc. You don't really need to contain all these loops in any other loop or structure. They can all reside on the block diagram next to each other. Ideally you will create subVIs for the data acquision and data processing tasks.
Message Edited by Mark Yedinak on 10-06-2009 04:29 PM
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

Multiple record acquisition on 5911

Has anyone tried a multiple record acquisition on the 5911 in Win95 ?
The niscope_initiateacquisition function takes a long time to get going
(anything from a few ms upwards), which means I miss a lot of lines in
the image I'm trying to grab. Do I need to tell Windows to stop doing
anything else during my acquisition loop ? If so how ? I've tried disabling
interrupts (using Borland _disable(), _enable() functions), which improves
things a little bit, but the problem's still there.

Hi David,
The first time you make a call to Initiate Acquisition will take a lot of
time because this is when all your configurations are sent down to the board.
I tried this here and found it took nearly 16 ms for this call and I have
a very fast machine (800 MHz).
It seems that you are starting your device and the NI 5911 at the same time.
Could you start the NI 5911 before your device? This way it will be up
and running and waiting for a trigger and you won't have to worry about this
delay.
In multi record acquisition, you only have to call the initiate acquistion
one time so after this call, the time between acquisitions will be very small
since it happens on the hardware and windows will not interfere.
"David Bell" wrote:
>>Has a
nyone tried a multiple record acquisition on the 5911 in Win95 ?>The
niscope_initiateacquisition function takes a long time to get going>(anything
from a few ms upwards), which means I miss a lot of lines in>the image I'm
trying to grab. Do I need to tell Windows to stop doing>anything else during
my acquisition loop ? If so how ? I've tried disabling>interrupts (using
Borland _disable(), _enable() functions), which improves>things a little
bit, but the problem's still there.

LeCroy wavesurfer acquisition loop slowdown

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