Reading digita signal

I'm looking to write a simple program code that reads digital signal from the PXI-7350 that I'm using. Using LEDs to display the signal whether its high or low.
Just looking for someone to point me the way on how to do this. Thanks

Hi odsnot,
you can search in the Example Finder for "DAQmx". You will find a lot of useful examples.
Mike

Similar Messages

How to input/output a digital signal and acquire an analog signal at the same time?

Dasylab, version: 8.0.04
Acquirement Card: PCI1002L
When I use DasyLab to acquire the analog signals is no problem without digital inputs and outputs,
and when I use DasyLab to input or output a digital signal is no problem also, but when I do that at the
same time, DasyLab tell me the rate is too high and stop.
so, I searched the manual book1 (user guide) for that, it showed me :
To internally equalize measurement time and system time in the analog input, digital input and counter
hardware modules, use the following settings:
   Synchronization: PC Clock
   Sampling rate: <= 5Hz
   Block size: =1
the problem is, if I set the Sampling rate to 5Hz, the speed of the acquirement datas is not enough for my
application.
so, how to improve it? who can give me a example programm for me. thanks!
by the way, I come from China, my English isn't good, I'm sorry.
Allen, China.

Hi,
Have things changed over the years?
I need to syncronise a digital output (Modul NI9474) and an analoge input (AI-Modul NI9203) module. I need to measure time intervals from a flank in signal A to a flank in signal B. I would like accuracies of the order of 1 ms. Currently, the signals are not synchronised, with errors of the order of 2 times the block length (block size x sample rate), sometimes much higher. The best I got so far was a block size of around 20 with a sample rate of 1 kHz.
If I use the master and slave settings on the RTSL settings, my program doesn't run properly.
If I use digital signals for input and output, I can syncronise them with RTSL settings and everything is good, but I can't always do that.
Also, if I do anything in the GUI (such as scrollowing something or going to another window), my output gets screwed up properly.
1. What can be done to synchronise AI with DO?
2. Is there something that can be done to avoid messing up the output when something happens in the user interface? (I know that I am messing up the outputs as they make some valves switch and that is loud).
Thanks in advance!

How do I convert analogue 5.1 surround sound into a digital signal? (Pioneer SE-DIR800C headphon

I understand that my SB Audigy 2 card will only output 5. sound from games through its 3 analogue connectors. How do I convert this analogue signal into a digital one? What hardware do I need to purchase?
I have read the thread on "Digital Connections, SPDIF and Dolby Digital Info", and also I've thoroughly read the "Creative Speaker Connectivity Guide".
The reason I ask is that I have just bought a pair of Pioneer SE-DIR800C Surround Sound headphones. This are supposedly fantastic for recreating surround sound on headphones because there is a clever little decoder box. They accept a DTS / Dolby Digital signal via the digital co-axial and optical inputs, and there is a single analogue input which only accepts stereo sound.
My XBox and PS2 will output true digital 5. sound via an optical cable and I am confident this will work perfectly with these headphones. I'm really looking forward to playing Halo in surround sound! But for gaming on my PC, I'll be limited to just an analogue stereo signal. Well, unless I can find some device that will convert my SoundBlaster's analogue 5. outputs into a digital signal, which I can then plug into the little decoder box for these headphones.
So, back to my question:
What hardware do I need to buy to convert an analogue 5. signal (via 6 x RCA or 3 x 3.5mm stereo ) into a true digital signal (via optical or co-axial SP/DIF)? Is it some type of headphone amplifier I need? If possible, please recommend makes & models of equipment.

Thanks stefan
OK, basically I have found 3 options for getting digital 5. out of a PC:
a) Creative DTS-60 (approx $90). This converts the SB's analogue into digital, but it's not available in the UK and it also introduces a noticeable 50ms sound delay. Also, who wants an extra box hanging out of their PC?
b) Buy a new sound card which has Dolby Digital Li've output. For example, ) BlueGears HDA X Mystique 7., or 2) Turtle Beach Montego DDL, or 3) Terratec Aureon 7. PCI (NOT the Space, FireWire or Uni'verse cards). I couldn't find the first two available in the UK so I have just ordered the Terratec card from Komplett.
c) Buy a new motherboard that has built-in Dolby Digital Li've output, for example the ABIT Fatalty AA8XE. Unfortunately my PC is only just over year old and I'm not quite ready to replace it.
I hope this info is useful for people. Maybe Creative will start making a card with DDL output too.Message Edited by NinjaHeretic on 2-22-2005 08:46 AM

How to check 6 digital signals change value at the same time with PCI-6229??

I am using DAQ card PCI-6229.
Channel 1 generate a digital signal.
Channel 2,3,4,5,6,7 acquire digital signals.
I want to check:
1. Whether the rising edge of Channel 2,3,4,5,6,7 occures at the same time;
2. The time delay from the rising edge of Channel 1 to the rising edge of Channel 2,3,4,5,6,7 is within a certain range.
I know I can use counter to get the two edge seperation time delay. But I only have two counter, it is two time-consuming if I check one by one.
I don't know how to check the rising edge of 6 different channels occure at the same time.
Does anyone has any suggestions?
Thanks

Hello,
You can use the DAQ card's digital input change detection circuitry to detect changes in the input, you can then use a counter to measure the relative time between samples. Please read Page 6-9 DI Change Detection Applications for more information. Let me know if this helps
Christian A
National Instruments
Applications Engineer

How to convert digital signal to analog

Hi..
I am using NI 9375 (DIO module) to read the output from flow sensor.
The output of the flow sensor is in the digital signal.(Boolean=True/False).
How can I convert the digital signal to the analog to get the reading of the flow sensor?
I had tried before to convert the digital signal to the frequency so that I can make the conversion from frequency to the flowsensor reading,
but it doesn't work.( I am referring to http://www.ni.com/white-paper/14549/en/ ).

nhan91213 wrote:
Hi..
I am using NI 9375 (DIO module) to read the output from flow sensor.
The output of the flow sensor is in the digital signal.(Boolean=True/False).
How can I convert the digital signal to the analog to get the reading of the flow sensor?
I had tried before to convert the digital signal to the frequency so that I can make the conversion from frequency to the flowsensor reading,
but it doesn't work.( I am referring to http://www.ni.com/white-paper/14549/en/ ).
FYI - If your flowmeter pulsing frequency is higher than 500Hz then you won't get reliable reading using your algorithm, and it will be very unreliable above 1kHz because fastest that loop runs is 1mS (1kHz). In that case you could tie the timed loop to a higher rate (hardware) clock source to go faster than 1mSec loop time. If no hardware then I think you can use high resolution timer (in LV2014, not sure if it was also available in previous version) and a regular while loop with algorithm modification for a faster timing.
New Controls & Indicators made using vector graphics & animations? Click below for Pebbles UI

Is the lightning adapter also pass trough the digital signal? Or only the analog?

I want to order a arcam dr dock. I am not sure, that it will work with the lightning adapter because it has only the 30 pin adapter and it will need the digital signal...

In the meantime I can reply my question by my own. The lightning connector pass also the digital signal trough.
So my new Arcam DrDock is working with new I Pad (4) with lightning adapter.

Counter Output as Sample Clock of Digital Signals

I have a situation where I need to use a hardware counter as sample clock of digital output signals.
How do you specify the "Counter Internal Output" signal as a sample clock of digital output?
I want to do something like this:
// Create counter task
  CNiDAQmxTask m_Task(_T("ATask"));
  m_Task.COChannels.CreatePulseChannelTicks(_T("Dev1/ctr0"), "", _T("20MHzTimebase"), DAQmxCOPulseIdleStateLow, 0, 10, 10);
  m_Task.Triggers.StartTrigger.ConfigureDigitalEdgeTrigger("PFI0", DAQmxDigitalEdgeStartTriggerEdgeRising);
// Create digital output task
  CNiDAQmxTask m_Task2(_T("ATask2"));
  m_Task2.DOChannels.CreateChannel("Dev1/port0/line0", "", DAQmxOneChannelForAllLines);
  m_Task2.Timing.ConfigureSampleClock("XXXXXX", 0, DAQmxSampleClockActiveEdgeRising, DAQmxSampleQuantityModeFiniteSamples, 400);
How do I specificy "counter 0 Internal Output signal" instead of "XXXXXX" above, i.e. the sample clock of the digital output signal. Can't find the name of the signal anywhere in the documentation and help files. I have a 6259 DAQ board.
/pek

Thank you for your answers, but I can't get it to work.
When I use "ai/SampleClock" as sample clock everything works correct. When I try to use a counter as sample clock the task completes imediately, before any digital signals has been sent/measured. The task even completes before I have started the trigger, which is very confusing. No error appears.
I think that something is wrong about how I setup the counter. I use the code below:
// Create counter task
CNiDAQmxTask m_Task(_T("ATask"));
m_Task.COChannels.CreatePulseChannelTicks(_T("Dev1/ctr0"), "", _T("20MHzTimebase"), DAQmxCOPulseIdleStateLow, 0, 100, 100);
m_Task.Triggers.StartTrigger.ConfigureDigitalEdgeTrigger("PFI0", DAQmxDigitalEdgeStartTriggerEdgeRising);
// Create digital output task
// The code below works with "ai/SampleClock" as sample clock
CNiDAQmxTask m_Task3(_T("ATask3"));
m_Task3.DOChannels.CreateChannel("Dev1/port0/line0", "", DAQmxOneChannelForAllLines);
m_Task3.Timing.ConfigureSampleClock("Dev1/Ctr0InternalOutput" /*"ai/SampleClock"*/, 0, DAQmxSampleClockActiveEdgeRising, DAQmxSampleQuantityModeFiniteSamples, 400);
// Create samples
CNiUInt32Vector ui_data;
for(int i = 0; i < 200; i++)
for(unsigned int j = 0; j < 2; j++)
    ui_data.Append(j);
// Create digital writer
CNiDAQmxDigitalSingleChannelWriter m_writer3(m_Task3.Stream);
m_writer3.WriteMultiSamplePortAsync(true, ui_data);
// Wait until task completes
m_Task3.WaitUntilDone(-1);

Acquire 2 digital signal with custom scaling (Engg Units)

I am a newbie to DIO world.
I have write a VI to acquire 2 digital signals. one from a load cell and other for motor rpm (pulses). I need to acquire these two signals and then convert them into engg units using custom scaling and write them to a txt file with time stamp.
Please suggest best ways to accomplish this task.
Thanks
DAQG
Solved!
Go to Solution.

Look at the examples on DAQmx in the example finder.
You wouldn't actually be acquiring 2 digital signals. You would be acquiring an analog signal from the load cell. A digital or counter acquisition is what you would acquire from the motor. Search for analog measurements and counter measurements in the example finder. Some of the example should show you how to apply the custom scaling.

Generate complementary digital signals with dead time between each pulse and controlled by duty ratio

I am to generate two complementary digital signals using NI 9606 conected by RIO Mezannine Card to NI 9683 (Half Bridge DO).
I am able to generate the signals but I am not able to put dead time between high and low signal and also, low and high signal.
Requirement:
(1) When the first signal goes high and the second signal goes low, there should be a controllable dead time.
(2) Also when the second signal goes high and the first signal goes low, there should be a controllable dead time.
I am able to do requirement 1, but I am unable to fulfill requirement 2.
Please have a look at my VI and let me know how to go about satisfying requirement 2.
Attachments:
complementary test 2.vi ‏69 KB

Hi Frank ,
I have already taken note of the example Tannerite has provided and have built my vi ( attached in previous post) surrounding that example.
Now I require to control the PWM duty cycle as you can see from the vi using a knob and that control refers to both the signal 1 and 2.
Now the signal 1 end and signal 2 generation requires a controllable dead time. Similarly, signal 2 end and signal 1 geneeration also requires another controllable dead time.
I am able to do either one dead time at a time using delay but not two dead time simultaneously.
I feel that I have two put the delays at the appropriate data flow point. I am working on that.
I would really appreciate if you could give some insight on how to solve this dead time issue and generate two complementary waveform with dead times whose duty cycle can be controlled by a knob controller in fronty panel .
I have also posted the required timing diagram for reference as suggested by Tannerite.
Best regards.

Sequence 1create output digtal signal- 2 make microseconds delay or less- 3 measure digital signal with board 6023e

hello
I need creat a digital signal and for this i use a counter output and then i need creat a delay after a signal measurment and for this i use again a couter. My problem is how i can make this delay betwen create and measure a signal. this delay must to bethe shortest possible and precise. une of my attemps was make a sequence and for make the delay i create a task for une virtual output with max frequency 5000000hz and just une pulse but i dont know how many time the labview get to go by the first task ( creat a output pulse and ent it) to make tis task before discribed to the last task (measure a digital sinal). Another thing that i dont know is how many time the libview get to create and eliminate une task. Une information beyond the kind of board (6023E) that can be useful to help me with this problem is the information about my pc in this case i use a pentium4 3Ghz.
thanks

...My problem is how i can make this delay betwen create and measure a signal.
...how many time the labview get to end one task and start another one.
What I tried to say is, that even if you use the counter of the 6023e-Board
to create the delay and trigger the measure via LabView under Windows,
you leave the realtime-path. Executiontime of LabView-code is then not
determinated.
One way to solve this, is triggering measurement via hardware and use LabView to read Data from the Buffer of the DAQ-card.
You can find more info about DAQ in the "measurements manuall" of NI, delivered with your LabView Software.
Lorand

Wait for the digital signal

Is there like "wait for the panel activity" in digital signal, "wait for the digital signal goes up" etc. ?
Or is it bad to make it with sequence structure and inside of first sequence use while loop?

If you need to wait for a digital signal before continuing on with your program, the best way is to have a while loop that continuously reads the signal and stops the loop when the signal goes high. You can put this loop in the first frame of a sequence, or you can wire an output from the loop (like error out from the device read vi) into your next step. Be sure to put a delay (100mSec) in your loop so that the loop does not hog CPU time.
- tbob
Inventor of the WORM Global

Is there a VI which reads audio signals off optical SPDIF port?

Hi,
I am trying to capture audio signals from a DAT unit on to the computer's hard drive. Could you please tell me how can I read these signals off an optical SPDIF port using Labview and save the streamed data as a wav file? I am using an audio capturing interface called the Edirol UA-5 to transfer the audio signals from the DAT unit to the Mac's hard drive.
Thanks,
Bhuvana

Hi Bhuvana,
There are not any VIs in LabVIEW designed specifically for SPDIF. There is, however, a tutorial on reading an SPDIF signal using LabVIEW FPGA. You may also be interested in this thread which discusses the use of a digital data acquisition board and the rate needed to read an SPDIF signal.
Jennifer R.
National Instruments
Applications Engineer

Digital Signal Modification (PCIe 6320)

Hi,
We've got a digital signal which is basically a series of trigger pulses for a receiving device, constantly pulsing. However, the pulses need to be modified so that e.g. only every third pulse ends up on the receiving device, but not more than e.g. 4 pulses, with a given delay of e.g. 2 pulses.
Using this example, input and output signal should look the following:
in : 1---1---1---1---1---1---1---1---1---1---1---1---1---1---1---1
out: --------1-----------1-----------1-----------1----------------
We've got it basically working using Digital Edge Counting and connecting/disconnecting terminals as needed. However, the task is very time critical and I'm seeking for a solution that works as close to hardware as possible (ideally, the task should be carried out by the card itself after setting up the parameters).
We've got a PCIe 6320 that we want to use for this task, we are programming in C using the DAQmx C library.
Thanks for your suggestions.

Since your real code is different than what was posted, I can only take some guesses for why you can't count more than (about?) 1 million pulses.
1. If your real code doesn't wire a "# of samples" value to DAQmx Timing.vi, then a continuous task that is told it's acquiring at 100 MHz will use a default buffer size of 1 million samples. You can create a bigger buffer by wiring in a bigger value. You can also loop over your Read calls to help prevent a buffer overflow.
2. Theres a limit to the rate you can stream data from the board to system RAM. The X-series is very VERY much better than most of its predecessors in this regard for counter-based measurements. (See this thread and associated links.) But it still won't handle 100 MHz effective sampling rates for any appreciable duration.
3. Another option I've seen used is count binning. That method works kinda inside-out from your method by letting the external pulses increment the count while that count is sampled at a constant sample rate.
4. I haven't yet been able to do any real-life playing with an X-series board, but I think there's also a mode for measuring precise frequency while sampling at a constant rate. That mode might prove useful for you as well.
-Kevin P

Generating digital signals (T/F) continuosly at certain frequency

Please help me in generating digital signals continuously (TRUE/FALSE alternatingly) in LABVIEW 7.1. I want them to be crreated at frequency which can be controlled by myself. Kindly help its urgent. Contact me at [email protected] Thanks Rahul

Have you looked at the shipping examples for DAQmx? What kind of DAQ card do you have?
p.s. since all questions are answered here, posting your email does no good except put you on a list of spammers.

Generate digital signal for 6722 or 6221

Hi,
first thanks for the help I already got on this board.
Now I've got the following problem:
I like to generate a digital signal: high for 300µs, low 300 µs, high 300µs, low 300µs, high for about 2ms.
I am looking for a solution how to generate this digital sequence. At the same time I will read the information back via an analog input (hopefully I have now a solution for this problem).
I tried to find examples but I wasn't successful. At the moment I was not able to produce any digital sequence which worked.
My hardware is either 6722 or 6221 - which should be OK regarding the timing.
Thanks
Solved!
Go to Solution.

Find attached example.
I am not allergic to Kudos, in fact I love Kudos.
Make your LabVIEW experience more CONVENIENT.
Attachments:
Digital Waveform [LV 2009].vi ‏14 KB

Reading digita signal

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