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,
I believe that the problem you are having is due to using the pause function to pause the acquisition before the next trigger and the fact that DAQpads do not have a DMA transfer mechanism. The default setting is to create an interrupt when the onboard FIFO buffer is half full. So when the pause trigger occurs there will always be data left on the FIFO, up to a half buffer of data.
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

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Digital triggering for analog acquisition on PCI-6024

I would like to initiate an analog input scan when a digital line goes low using a PCI-6024 board. I connected the digital line to TRIG, and the analog line to AIN0. I tried using "Acquire N - Multi-Digital Trig.vi"...it almost works. It acquires a scan, but it may (randomly) start at either the rising or falling edge of the trigger, regardless of the rising/falling trigger edge setting. How do I get it to only acquire data on a falling edge?

Dear Dave -- If you set up your task using MAX, you can specify whether you need to start acquiring at the rising or the falling edge. Using this task in your experiment should effectively take care of the issue.
You can do the same from LabVIEW as well using the DAQmx Trigger VI and set the acquisition to begin at the rising or falling edge as you may choose it to be.
HOpe this helps = VNIU

Error -200279 with simultaneous analog input (different devices) and digital output.

Hi guys,
I am a beginner in Labview and have been dealing with this problem for a couple of weeks now and just can't seem to get it completely right, I have a feeling there are a few small bugs in my code/hardware setup.
I am running an scxi-1000 chassis with a 1600 module and 1302C along with a 1303 accesory for temperature measurements, this is connected to four thermoucouples. Unfortunately I have a limited number of modules available so I am also using a PCI-6221 DAQ card with an scb-68 breakout box used for a digital output and analog input voltage channel. Attached is my labview program. When I run the code at a 50 Hz sampling rate it runs with no errors but the data file comes out extremely wrong, this is also attached. When I run the code at 100 Hz I get error-200279 after a few loops. I used to have 2 daqmx timing VIs (one for each input), but the same error would eventually happen, I have also tried increasing the buffer size on said timing VI. I am also using an old computer (Pentium IV) could this effect the program?
I have learned a lot going through forms for similar problems to mine but I just can't get it to for an extended period of time, I have posted my simplest code.
Thanks in advance,
Luca
Attachments:
tc_2.txt ‏1102 KB
FinalCombined_2.vi ‏128 KB

Ok this makes sense. I have made the suggested modifications but still getting the same error with sampling rates of 100 Hz or higher. Could you check that I have implemented the queue VIs properly (new file attached)? Also when running at 50 Hz in debug mode it does not look like the second while loop (with the dequeue element) comes into play until I hit the stop button, once I hit the stop button I get the following error:
Error 1 occurred at Dequeue Element in FinalCombined_2.vi
Possible reason(s):
LabVIEW: An input parameter is invalid. For example if the input is a path, the path might contain a character not allowed by the OS such as ? or @.
=========================
NI-488: Command requires GPIB Controller to be Controller-In-Charge.
This leads me to believe I have programmed the queue elements incorrectly.
Thanks for your help, any suggestions are greatly appreciated.
Luca
Attachments:
FinalCombined_2.vi ‏102 KB

Simultaenous digital out and analog in

Hi. I am running into an issue with the simultaneous AI (analog in) and DO (digital out) with Athena (www.diamondsystems.com) and LabVIEW (see the supplied files): The original program example supplied by somebody (the attached 060126 file) runs fine with these two simultaneous operations.
However, for my specific requirements, I would have to put a frame (flat sequence) around the DO part (the attached 060131 file), followed by another flat sequence frame that changes another DO state. The reason that I must do this is that I have 2 valves which change states as the AI operation continuous to run.
I have noticed though, once I put those flat sequence frames around it, the DO pauses and doesn't perform the operation until the AI loop is stopped. I have tried to create various local variables but the issue persists. Would there be a workaround for this? Thanks.
Attachments:
HMIR_SBC_060131.vi ‏374 KB
HMIR_SBC_060126.vi ‏137 KB

I have taken a look at your code. Based upon your description,
and the fact that I do not have the driver for your device, I am not exactly
sure where the program is pausing. I can give you some suggestions to
resolve your problem. When you use a flat sequence structure, every piece
of code in a frame has to finish execution before the next frame will start
execution. If you have code in parallel (i.e. digital output and analog
input) in one frame and the same in a second frame the digital output and analog
output in the second frame will not start until all the code in the first frame
has finished execution. In your case it you have a while loops for
digital input and output in the first frame. When both of these loops
finish execution, you should see the second frame start shortly after.
From your description what I believe is happening is that the digital output in
the first frame is finishing and waiting for the analog input to finish.
After the analog input loop finishes the second frame can start. If you
want the second frame's digital output to start before the loop finishes
execution you will need to take that code out of the frame.
Regards,
Jesse O
Applications Engineering
National Instruments
Jesse O. | National Instruments R&D

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.
Use the Cont Acq&Graph Voltage-Int Clk.vi example for your analog measurements. (NI Example Finder) For your digital IO you can only use the examples like Read Dig Chan.vi, Read Dig Port,...
There are indeed some slow performance issues with single point I/O Operations, that is correct.
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.
For example, on the DAQPad-6020E, timed non-buffered analog input operations are limited to about 50 Hz. At higher rates, the software may become unresponsive. On a FireWire device, you can expect stable operation around 3,000 Hz. But again, these figures are system dependent.
Regards.
JV
NI

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

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

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

Digital outputs while sampling analog inputs

I am currently developing a program using LabView 2012 SP1. I am interfacing with a NI USB-6009 DAQ using NI-DAQmx 9.5.5f4. I am attempting to acquire a voltage reading on three analog inputs (AI0, AI3, and AI4) at 1 second from startup and at 20 seconds from startup. The three digital ports: P0.0, P0.1 and P0.2 are used to turn on transistors for the signals in question and must remain high during the ~20 seconds the readings will take place. I have figured out how to acquire 20 samples over 20 seconds on the analog inputs but have trouble with the digital outputs. The DAQ assistant is not a good option and the USB 6009 has limitations that are not necessarily covered in the example code im finding. Basically I need to turn on (write hex 7) to port P0.0-2, acquire my analog samples for 20 seconds, then bring port P0.0-2 low and end the program. Can anyone help walk me through this? Thank you in advance.
RJ
I surf therefore I am....

Solved it. See attached vi.
I surf therefore I am....
Attachments:
Level.vi ‏69 KB

How to use Digital output to turn on sensor for Analog Input?

I am trying to use a digital output to turn on an array of sensors that I then wish to read on 16 analog input lines. I have a 6024E DAQ card. I am planning to take data at 10-20 hz, so not terribly fast, but I will be acquiring for long periods of time (days) so I will be streaming data to disk.
I have a fair bit of experience in Labview basics, but can quickly get out of my depth when I try something new (like this). I have V6.01.
It looks as though the best way might be to do the DO and then a single AI as individual events, then write to disk and continue through the loop. I am puzzled, however, how to keep this cycle on schedule given that I don't know how long it will take to sample 16 channels
, write the data to disk and get back to the starting point... perhaps this is so fast that I don't need to worry about it? The actual timing of the samples (be it 10 or 20 hz) isn't too critical, as long as I can record at what time they were taken... it would be frustrating to find that I was several seconds off after days of data.

Hello,
Thank you for contacting National Instruments.
If you are worried about the time of your acquisition being off, then you should associate each voltage measurement with a timestamp. This will allow you to know the exact time at which the sample was taken and you will never be off. You can use the Get Date/Time in Seconds.vi in our while loop with your AI code so that you can read a sample and read the time. You can than log the voltage value and the timestamp to your file.
Regards,
Bill B
Applications Engineer
National Instruments

PID Control - analog input, digital outputs

Hello everyone,
I am trying to use the PID toolkit to convert my existing feedback control system to one using PID or just PI whatever works best. Problem is that the tutorials out there discuss in detail about obtaining Analog inputs and using the PID output to control an analog output. Are there any tutorials that show how I can control my process variable which is an analog input by using the PID output to generate digital outputs?
Basically, what I am doing is controlling the incline of my device with two digital outputs that control two solenoid valves. The angle is calculated from a calibration curve that plots distance sensor voltage with Angle. Any help would be immensely apprecitated. I want to try this out on my own before I post some vi's. Thanks!
V
I may not be perfect, but I'm all I got!

That is exactly what I am doing currently. I have error bands specified around the target to make sure that it doesn't oscillate. But, under load conditions such as pulsed load conditions, the device goes out of bounds and the values trigger to correct for it. But, what I need is seemless or atleast seemless correction. Currently what I see is sudden adjustments to the incline. Please find attached what I am currently using. I am trying to get a more finer solution if at all possible.
Note: Within 5% of the target = NO action
Between 5% and 15% = Pulsed ACtion ( DO On for Pulse width time)
Greater than 15% = continuous action until it reaches Pulse band
I may not be perfect, but I'm all I got!
Attachments:
TDML_subElevationControl.vi ‏41 KB
TDML_subPulsedValveFuntion.vi ‏16 KB

NI DAQmx Digital Output Trigger To Start Analog Input Task

Hi everyone. I am using the NI DAQmx VIs to set a digital output line low (boolean '0'). I want to begin reading an Analog Input voltage (Start Analog Input Voltage reading task) right after the digital output line is set low. I am using the DAQmx Start Trigger (Digital Edge).vi to try and do this. I have the digital edge to trigger off a falling edge since the digital output line is being set low. I am using "do/SampleClock" as the source into the DAQmx Start Trigger (Digital Edge).vi.
I don't have the DAQ card (PXI 6229) since someone else is using it but I wanted to write up the SW so that when it becomes available I can have SW to try out.
I have attached the VI. Am I setting up this VI correctly?
Thanks!
Attachments:
Trigger AI Task Off DO Edge.vi ‏32 KB

I think you are going to have to wire that Digital Output to a PFI line on the card with the Analog Input(s). You then trigger on that PFI line.
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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.
The digital examples are in the LabVIEW >> Examples >> Daq >> Digital >> E-Series directory. The Generate Retriggerable Pulse example is in the LabVIEW >> Examples >> Daq >> Counters >> DAQ-STC directory. The E Series boards use the DAQ-STC timing chip.
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

How to use both digital and analog input modules in the same worksheet - MCC USB1208LS

Dear all,
Hi, I am Imran. I am using MCC USB1208LS. I have created the worksheet using digital input module as below and able to execute (run).
But when i add another analog input module in the same worksheet and executes, An error Message pops-up as in the below image
I have connected temperature sensor sognal to the analog input of USB1208LS. When using analog input alone in the worksheet, it indiates the actual values.
is any black box solve? please guide me. I am attaching in images
We already placed a purchase order for USB1208FS. Will it sort out my issues?.
Thanking you,
Imran Mohamed.
Attachments:
present worksheet digital input only.JPG ‏67 KB
with analog input module.JPG ‏81 KB
error menu.JPG ‏77 KB

Hello Imran,
the USB-1208LS is not capable of running concurrent operations such as an analog input scan and ANY digital Ins, Outs, counter reads, or analog outs. In Dasylab, the 1208LS is scanning, and nothing else from that particular device can be requested of it while that is happening.
Yes, using the 1208FS will resolve some of these issues.
Please refer to the ULHELP.CHM file installed on your computer in c:\program files\measurement computing\daq for details on this issue, et al.
also I recommend you send your MCC/DASYLab requests for support to [email protected] as MCC staff (that includes me) does not normally monitor NI's Developer Zone.

MyRIO analog input express Vi (n samples) missing file

Dear Users,
I am trying to read analog data with an express VI in myRIO. This works with Analog input (1 sample), but fails with Analog input (n samples) due a missing file "myRIO v1.1 FPGA Throughput.lvbitx".
I googled it and searched it on ni.com, but nobody seems to have the same isssue (I suppose because of the myRIO is quite new right now)
Thank you!
Solved!
Go to Solution.

I would try doing a repair of your installation. It looks like something didn't get installed properly.
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DAQPAD 6020e misses digital triggers during analog input (AI)

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