Triggered and continuous analog input togeather?

Hi,
I have a program set up based off a shipped LV example involving digital triggering of the analog inputs. It looks at a pulse and reads in ten points from the rising edge continuously. It appears that we are missing some pulse triggers and only reading in 126 triggers/sec instead of 128. We double checked the pulse and the frequency is correct (128Hz) so it seems as if the LV program is missing some of the pulses. Therefore, I want to use another analog input channel on the same 6062E daq card to continuously read in the waveform and see which pulses are being skipped. Is this possible?

Lisa,
I don't believe the E-series architecture will allow triggered and continuous analog input operations to occur in parallel. It is possible to set up different gains/input ranges but I'm 95% sure that the functionality that you are after isn't there.
If you are looking to keep track of the number of pulse seen by your application you could consider the use of a counter to count the number of rising edges seen by the NI 6062E - basically daisy chain the pulse train to the trigger input and the GP_CTR Source pin of the counter you wish to use. There are a number of examples around that should help with this. Running the counter and analog input operations in parallel shouldn't be a big problem - it might be that you would want to set up a buffered event co
unt operation for the counter as this will allow you to track and monitor every single trigger event seen by the counter while your analog input operations continue in parallel.
The other aspect to consider is benchmarking your application with the Profiler. If the problem is that you consistently only see 126 triggers/second, perhaps your acquisition loop is not running fast enough to cope with the data. This can be especially true if any data processing or file storage is taking place inside the acquisition loop. The Profiler will allow you spot bottlenecks and get a better understanding as to the performance of your application.
I appreciate this is perhaps not a direct answer but hope that it gives some ideas as to how to track down the cause of the problems you are experiencing.
Jeremy

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Newbie: 6020E (USB) slow performance with mixed digital and analog input

Hi,
I'm using a 6020E to do analog and digital input, and I'm getting very bad performance.
Please note that doing IO in Labview is new to me!
I have read the post about 6020E slow performance, and it says I should do buffered IO.
Can anybody point me to some DOC or SAMPLE that actually shows or explains how one should do this. I need to read several digital IO lines (which I can combine in one port-read), and several analog inputs.
Seeing how slow the reading on the 6020E is, I am amazed there is only one post that deals with this issue.
I would be satisfied to get the 6020E into some sort of continuous read mode so that whenever I need data, I get the latest reading right away.
thanks,
Peter D'Hoye

Hi Peter,
Your cannot do buffered digital I/O with your daqpad. It doesn't have that capability. You can only make direct software calls with digital read/write from/to your port. So your digital IO is completely software clocked and not hardware clocked. The example you are trying is only for specific Simultanuous sampling boards or now also for M-series boards that are able to do correlated DIO.
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Check the explaination below:
DAQPads are offered for the Universal Serial Bus (USB) and the IEEE 1394 (also known as FireWire). Both of these standards use a high-speed serial communication protocol between the computer and the device with a bandwidth up to 12 MB/s for USB and 400 MB/s for FireWire.
During a single point operation, the DAQ device requires a complete set of configuration commands. This is done through serial communication (USB or FireWire), making the process slower than in a PCI-based board. The speed obtained for single point operation in a DAQPad is system dependent; this means that your computer processor, memory, bus speed, and other factors alter the speed at which you can do single-point operations with a DAQPad.
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PXI-6230 analog input trigger setup

Hi,
Can anyone point me in the right direction of how to configure the PXI-6230 card to implement 3 of the analog input channels as a digital input trigger? The input to each channel is TTL pulses. I want to have a trigger event on every pulse from any of the three inputs. I'm using LabVIEW 8.5. Any help is appreciated. Thanks.

Hey HarveryL,
I'm not sure it is possible to do this. Can you give me some more details on your application, and why you want to use the analog inputs as a digital trigger? Here is an article on how to use PXI triggers with the analog input and output, perhaps you can adapt that code to your purposes. I'll continue to look into this for you, but any more information you can provide would be appreciated. Have a great week!
John B.
Embedded Networks R&D
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Certified LabVIEW Developer

Application exe not displaying analog input measurements

i am using the compactDAQ cDAQ 9172, after building the exe all the other digital and analog output ports are working properly whereas the analog input section is displaying the value as Zero, if i read read this channel from the max, it reads the values without any errors.what might be the issues.

Hi Kodeeswar:
I have a couple suggestions first try to create your analog input application with no digital or analog output task just "analog input" and then build the executable and try it again; second if it is possible for you please try updating to the new drivers of (NI DAQmx), and third reinstalling the last version of the “labview run time engine”. Also the 9172 is the chassis so which module are you using to handle the Analog Input application? To synchronize multiple modules or chassis if this is your case these links might be able to help you so please take a look at: NI CompactDAQ Module Synchronization, Synchronized Continuous Analog Input Across. I hope I was able to help you.
Jaime Hoffiz
National Instruments
Product Expert
Digital Multimeters and LCR Meters

Can I read more than 2 analog inputs from myDAQ?

Hello,
I am trying to read 3 voltage values. However, the myDAQ only has 2 analog inputs.
There are multi-meter ports in the myDAQ as well. Could I read the 3rd value via this port?
How would I read these values via the DAQ assit on labVIEW?
Thanks in advance.
Yzhi

Hello Yzhi,
You can acquire from the DMM and the analog inputs using two parallel tasks. The simplest way is to configure one DAQ Assistant for the AI channels, and another DAQ Assistant for the DMM channel. Be aware that the DMM is a software-timed single-point measurement (no hardware waveform acquisition), so you can't tightly synchronize the DMM with the Analog Inputs.
Here is a screenshot demonstrating how to acquire from all three channels. You could also run the DMM in a separate loop so it doesn't slow down AI.
Good luck and let us know if you have any other questions.
Charles Y.
National Instruments
Attachments:
myDAQ acquire two AI and DMM.jpg ‏196 KB

Synchronize hardware timed buffered counter acquisition with buffered analog input acquisition

LV7.1
DAQmx
PCI-6036E
SC-2345
Windows 2000
Greetings.
I am simply trying to synchronize AI readings with readings from one Counter.
I am trying to perform buffered analog input synchronized with buffered counter acquisition.
I'd like the AI acquistion to trigger the Counter acquistion.
I'm currently setting the Sample Clock Source for the CI Cnt Edges Task to "Dev1/ai/SampleClock" but when I try and set the source for the "DAQmx Trigger" I can't seem to select one that works. I assumed that the source should be the "Dev1/ai/StartTrigger" but that produces and error as does selecting any of the PFI's.
I'm new to DAQmx and didn't have any luck with the examples or what's been previously posted.
Thanks for your help.
Attachments:
Initialization.jpg ‏84 KB

Gentlemen-
All of your initial help was great. I had some noise on my counter lines so switched from an E-Series card to a PCI-6259 M-series card in order to use the counter digital filters.
Now I can't get a corellated buffered counter and buffered analog input acquistion to work. This same code worked fine on an E-series card but it doesn't on the M-series.
I verified that the source and gate of the counter are working properly using the test panel and a external function generator.
But when I run the attached code I get no data out of the "Counter 1D U32 NSamples", only an error saying that the timeout of the function was reached and no count data became available. Am I missing the specification of a another clock or something?
The counters also work fine using the M-series example code "Count Digital Events (M-Series DAQmx) but this is not a buffered acquisition.
Any help would be greatly appreciated.
Steve
Attachments:
Sample_Code.jpg ‏136 KB

"Out of range" error at analog input

Hello!
I use a PCI 1200 card with Nidaq 6.6.0 and Labview 5.1 support files on Windows NT for data aquisition. My programm has one digital channel and three analog input channels. I didn't write the programm myself but bought it in 1999 together with an apparatus which delieveres all these signals. I have only a Labview Executable which runs with LabView Runtime Engine 5.1.1 and the daqdrv, the serpdrv and one .lrm file.
The programm was running fine till the computer broke down. I had to reinstall the whole system and everything seems to work except the readings of the three analog input channels (one K-thermocouple and 2 times voltage). In the MAX the test panel says "out of range" for the channels. The digital channel (which is for switching valves in the apparatus) works fine!
What can be wrong?
- It's not the PCI card, I borrowed another one - it produces the same readings (And I tried all PCI buses in the computer)
- The Measurement and Automation Explorer MAX recognises the card and the card passes the test.
- I tried different settings like DIFF, NRSE and RSE, bipolar and unipolar but nothing changes for good.
- The settings of my four channels were saved in the daqdrv, that's why I think the mistake is not in the channel settings, but somewhere else.
I have checked the "Checking your board settings" support files from NI but nothing seems to help.
Any idea from you will be much appreciated!
Thanks a lot!

Hello,
You should update your NI-DAQ driver by downloading and installing the following links:
http://digital.ni.com/softlib.nsf/websearch/50F49E43A22C0D2186256BF3006B9A96?opendocument&node=13207... (choose the right one)
http://digital.ni.com/softlib.nsf/websearch/E470663AFB8A9EDD86256D8800543B4B?opendocument&node=13207...
I hope it will work after the updates!
Regards
Christian Mergl

ELVIS Scope and Analog input triggering

Hi everyone,
I'm trying to read two waveforms, one from the analog input and one from the scope. These waveforms are coming from two sides of a voltage divider and should always be in phase. But I think that there might be a triggering problem. When I change the frequency of the input waveform, my measured waveforms go out of phase.I have programmed each express VI to trigger off of the SYNC.
I can't use analog inputs for both measurements because the sampling rate is too small. I can't use the scope for both inputs because one of the waveforms is a differential measurement.
Any help would be appreciated, thanks.

Hi, I looked at the ELVIS Hardware User Manual and noticed that you have 12 channels that can be used as differential, Reference single ended or non reference single ended. Unless you have them all busy I don't see why you can't use the analog inputs. About the sampling rate, it will be determine by the M Series DAQ device that you are using and the source of the signal. It is a good practice to sample, at least, 10 times faster than the frequency of the input signal. The documentation of the card should show what the maximum sampling rate is.
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Good luck!
Alejandro | Academic Program Engineer | National Instruments

Can I use the 2 digital triggers on the PCI-6023E to trigger 2 seperate Analog inputs on the same board?

I want to monitor 2 analog DC signals (single point measurements, not a waveform) and I want to use the digital triggers to start the acquisition, 1 trigger for 1 AI. the measurements need to be made at 1Hz, maybe slower. Is this possible with the PCI-6023E?
If not what hardware should I be looking at? I have a total of 6 triggers and 6 AI.

Dimentia,
I would need confirmation on what you want to do:
1) I want to monitor 2 analog DC signals
This means that you will have one Analog Input operation monitoring two channels. Please confirm.
2) single point measurements, not a waveform
Ok, no buffers.
3) I want to use the digital triggers to start the acquisition, 1 trigger for 1 AI
This would mean that a single digital pulse or edge on a single line would start your 2-channel analog input operation. Please confirm.
4) the measurements need to be made at 1Hz, maybe slower.
Hardware-timed or software-timed? 1 Hz could be easily implemented with software timing. But the triggering could force you to use hardware timing. It will not be a problem but it would be good to know.
5) Is
this possible with the PCI-6023E?
Everything I mention above is possible with the PCI-6023E.
6) I have a total of 6 triggers and 6 AI.
This last phrase is what really confuses me and seems to contradict the previous sentences. Does this mean that you will want to perform 6 independent Analog Input operations, with its own triggers (one each)? Will every Analog Input operation have 2 channels?
I'll clarify why this is important:
- Each Analog Input operation can only have one hardware digital start trigger assigned to it.
- Only one Analog Input operation (multiple channels allowed) can be performed per board at any time.
Since the rates are so slow I would recommend that you perform sample all channels within a continuous acquisition and then discard the data that does not meet a certain condition. You could sample the triggers as well and discard those channels for which the trigger has not been received.
These are just some ideas based on my assumptions on the
problem. Assumptions are never a good thing so please confirm on the point s above and we'll try to help.
Thanks
Alejandro Asenjo
Applications Engineering
National Instruments

Analog input to modulate triggered sine wave analog output

I'm new to Labview and having trouble getting my app to program correctly.
I would like to use an analog input (AI) to modulate the amplitude of a
100 kHz sine wave and output the results to an AO. This is a real
time application: the AI will change every few 10's of ms so during one
"cycle" the amplitude will be modulated many times. Plus, the entire AO
will be triggered on and off with a digital input TTL trigger. The
waveform "cycle" will run continuously and so will the AI.
I've used an example included with Labview to read
the AI and a separate one to generate the sine wave and trigger it on
and off, but cannot combine the two together. I assume what I need to
do is implement a loop properly but when I try I can only trigger the
AO on and off and the AI does nothing or is static. I assume that the
vi just takes one point from the AI and uses that to determine the
amplitude of the sine wave, but doesn't "redraw" the sine fast enough
to respond to the AI changes.
Thanks,
Ethan

Hal,
I do not think I have Labview Realtime (unless it comes standard with the full version of Labview ). Do I need to have that? I have a 6251 DAQ board.
I've enclosed my program- it has the name of the original included program in its file name so you can see that I didn't do much to change it. I made some changes today (to make it non regeneration) but now can't get the AI to read at all. And I have no idea how to modulate the sine amplitude using the AI.
The sine wave works fine and triggers as needed. The one problem is that the sine wave doesn't end at the same point (phase) each trigger period so during the times between triggers the DC level on the AO is variable (which I do not want). Is there a way to end the sine wave at the same phase (at the zero crossing) while still triggering it with a digital input.
Thanks,
Ethan
Attachments:
ERB6-Cont Gen Voltage Wfm-Int Clk-Non Regeneration.vi ‏157 KB

Analog Triggering and Interrupt generation on the PCIe-6320 under Linux

We would like to use the analog triggering functions of the PCIe-6320 under Linux to time tag external events.
I have no experience with the MH DDK but have been told this is what we would need to implement the functions we want. We plan on using Fedora Linux and we are targetting kernel 2.6.31 with the PREEMPT_RT patch applied. We may consider slightly more recent kernel versions. The PREEMPT_RT patch is used to greatly improve determinism in the system and get real-time responses to some external events.
Here is what we wish to do in more details:
We wish to route at least two analog inputs to the comparator, then route the output of the comparator to a digital input which in turn would create a PCIe interrupt. The interrupt software handler would than time tag that event for our application purposes. We need the comparator threshold to be software programmable in level and slope. We are also interested in using the Watchdog Timer feature of the board.
Our application is written in C/C++.
Would the above be feasible? Please provide comments and instructions how we should address our requirement.
Thanks!

Patof wrote:
I am not familiar with the MHDDK. I would like to have an idea of the effort required to implement the functions I have described using MHDDK on Linux. Like I mentionned, we plan on using Linux kernel 2.6.31 with the PREEMPT_RT patch. Could you provide comments on that matter? I need to evaluate the amount of time I will need to spend to deploy and use MHDDK for the PCIe-6320.
There are two factors to consider when writing a driver for your specific application:
Using the deterministic kernel API calls
Writing to the device registers to
Control the watchdog timer
Configure the analog comparator
Manage the analog subsystem state as trigger events occur
Handle device interrupts
The MHDDK for X Series offers the following behavior out-of-the-tarball:
A Linux kernel module using the standanrd kernel and PCI subsystem calls
Mapping device registers to user-mode for access
Demonstrating/documenting how to
Control the watchdog timer (dioex6.cpp)
Manage the analog subsystem state as trigger events occur (aiex2.cpp, aiex4.cpp)
Handle device interrupts (reference manual only)
There are two notably missing pieces and one item to consider:
Missing: deterministic kernel API calls. If you decide to use the nirlpk module, you would need to change it from the standard interfaces to the deterministic variants.
Missing: configuring the analog comparator. You will need to implement this with additional insight from this discussion board.
Consider: if your application requires device access from kernel-mode only, you would not be able to use the MHDDK's C++ classes that perform device programming but would need to implement register programming in C.
To estimate the time for these three, here are my recommendations:
Review the nirlpk.c source file to understand how device access and DMA buffers are implemented and mapped to the user-mode application.
Beware that operation-specific programming help (as you would need for analog triggering) typically requires two weeks for a complete response.
Review the ChipObjects in the MHDDK distribution to understand how register addresses, widths, and bit fields affect device programming.
Joe Friedchicken
NI VirtualBench Application Software
Get with your fellow hardware users :: [ NI's VirtualBench User Group ]
Get with your fellow OS users :: [ NI's Linux User Group ] [ NI's OS X User Group ]
Get with your fellow developers :: [ NI's DAQmx Base User Group ] [ NI's DDK User Group ]
Senior Software Engineer :: Multifunction Instruments Applications Group
Software Engineer :: Measurements RLP Group (until Mar 2014)
Applications Engineer :: High Speed Product Group (until Sep 2008)

How to combine Digital Output, a delay and Analog Input in a fast loop

I need to develop a process loop that runs at least at 250 Hz that performs a Digital output, than a delay of 50 microseconds and than an analog input of all the channels. All will be done using ATI MIO 64E3 card. Of course, the acquired data will be processed, displayed and saved. The loop will be running for several minutes until user stops it.

The fastest and most precise timing will occur if you use hardware timing. You can apply hardware timing to analog input on the E Series boards, but not the digital lines. Let's focus on the analog input first. Continuous waveform scanning uses a scan clock, which can be the board's internal one or an external one which you apply. If you want to scan all the channels 50 microseconds after a digital rising edge, then you need an external signal to signify that scan clock.
The E Series boards also have 2 counter/timers onboard that you can use for this purpose. You can set up a retriggerable pulse generation operation, where the counter receives a trigger and then on the user specifications, produces a pulse. You can have that route to the analog input scan clock.
The trigger signal for the counter is that digital pulse. As I mentioned earlier, there is no hardware timing for the digital lines on an E Series board. We do have other digital boards (653x family) that have hardware timed operations if precision is important. If you are satisfied with software's resolution (in the milliseconds), then you can call the E Series board digital function in a loop with a software timer. That digital line can route to the counter to act as the trigger.
So, on the programming side, you can have three separate and independent operations in parallel. One is for the digital function to output on that line every so often. Another is for the counter set at the retriggerable pulse generation. The last is for the analog input. I will describe this in terms of LabVIEW, but it can be done in a similar fashion with the NI-DAQ function calls or Measurement Studio.
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Go to the LabVIEW >> Examples >> Daq >> anlogin >> strmdisk.llb directory and start with the Cont Acq to Spreadsheet File. This shows how to continuously acquire data and stream it to disk while displaying the data on a chart. Streaming to disk is the efficient way to save data while you are acquiring, as it eliminates the overhead of always opening and closing the file through the iterations of the loop. This saves to a file that can be opened by other applications (Excel, Word, etc.), but it is not as fast as writing to a binary file, which must be opened and read back through LabVIEW. However, for your ~250 Hz rate, it should be fine. Then, go to the LabVIEW >> Examples >> Daq >> anlogin >> anlogin.llb and look at the Acquire N Scans -ExtScanClk example. This shows how to apply the scan clock. Here, the AI Start that you saw in the previous example is replaced by 4 VIs (3 AI Clock Config's and the AI Control). Make those changes to the first example and then add a constant 0 to the AI Control parameter for total scans to acquire. That specifies the continuous operation. The File >> VI Properties >> Documentation menu item of the example describes the physical connections.
If you aren't using LabVIEW, use the NI-DAQ User Manual and the NI-DAQ Help file installed on your machine. You can look at your AT E Series User Manual at the http://www.ni.com/manuals pages for more information on the hardware. Also, if you want to route those signals internally on the board, you can find some entries in the KnowledgeBase at the http://www.ni.com/support pages.
Regards,
Geneva L.
Applications Engineering
National Instruments
http://www.ni.com/ask

DAQPAD 6020e misses digital triggers during analog input (AI)

I am using a 6020E BNC DAQPAD to acquire two seperate 12kHz analog signals from a sonar through ACH0 and ACH1. The sonar generates a digital start trigger at the start of each ping to notify the DAQ that new data is to follow and i am using this to trigger my application through PFL0/ TRIG 1. Typical trigger repetition rate required/generated by the sonar is 20-30Hz but is selectable. My problem is that the board/software misses complete analog input data pings when the digital trigger repetition rate goes above 2-3HZ (ie I only receive 10% of the pings I desire). Analog sampling rate is 45kHz and I am acquiring 1-2kSamples per triggered acquisition. The problem happens using a Labview application based o
n a modified version of the shipped "Acquire N - Multi Digital Trig.vi" (and original). Any suggestions welcomed.

Hi,
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To work round this problem you can use an external stop trigger instead of the pause.
Or it is possible to change the data transfer mechanism to cause an interrupt on every sample acquired instead of every half FIFO buffer. This will send every sample acquired by the DAQ board to the computer. The drawback is this method is very processor intensive and significantly slows
down data acquisition rates. As you are approaching the sampling limit of the card (100Ks/s or 50Ks/s for 2 channels) you may find that you will get buffer overflow.
To change the interrupt setting use the "Set DAQ Device Information.vi", which is located on the Functions Palette » Data Acquisition » Calibration and Configuration. See the LabVIEW help for information on using this VI.
Kind Regards
Tristan J
Applications Engineer
National Instruments

Time measurement between counter output my device and analog input

Hello!
I'm trying to measure the time to generate a digital pulse train on the counter output, that goes to a frequency converter that controls a motor. So I think it'd be the best way to wire the output of the frequency converter with an analogue input and make a timestamp before I generate the pulse and a timestamp when I recognize the singal, but I think that wouldn't be a serious measurement ?
What's the best way to measure the time?
kind regards peter

hi there
well, there a several ways to do this. the problem with the software - timestamps is the minimal resolution of 1ms. i'd suggest:
- wire a copy of the digital pulse train to an analog input channel
- wire a copy of the frequency converter to another analog input channel
- create an analog input task with the two channels (the sampling rate defines the timing resolution,make sure to acquire enough samples to see the response signal)
- start this task
- send the digital pulse train
to optimize your acquisition you can use another copy of the digital pulse train as a start trigger for your analog acquisition.
-> then you'll see the digital pulse train on one of the analog channels and the frequency output on the other one. both channels have the same time axis with a resolution defined by your sampling rate (~us depending on your hardware). then you can analyze the data.
search the example finder for examples of how to create tasks and triggers.
Best regards
chris
CL(A)Dly bending G-Force with LabVIEW
famous last words: "oh my god, it is full of stars!"

How to combine the analog input and analog output vi's

Hi !
I have a perfectly running triggered analog input acquisition vi. I have a seperate vi for analog output that's running perfectly too. Can someone tell me how to combine these two operations so that I could get a vi that does simulataneous AI and AO without missing triggers. I have tried all the different kinds of configurations suggested by NI support but nothing seems to work. Can someone help ?
thanks,
Shiva
Attachments:
dac_good.vi ‏77 KB
adc_good_fw.vi ‏124 KB

Shiva;
I'm attaching a good Application Notes that shows how to synchronize multiple DAQ tasks, in Labview.
Hope this helps.
Filipe
Attachments:
Advanced_Sync_Techniques_for_DAQ.zip ‏166 KB

Triggered and continuous analog input togeather?

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