Generate/Read Digital Pulse - What clock to use?

Hi,
I am using the NI cDAQ-9172 (with output module NI 9472 and input module (9421). I am trying to generate a pulse, run it through a system (just a resistor at this point) and then read it back into labview. I am able to generate the pulse with no problem, but anytime I try to read it I get an error regarding the clock. Any suggestions?
Thanks,
Solved!
Go to Solution.
Attachments:
Generate and Read Pulse.vi ‏30 KB

Looks like i figured it out. I had the clock said as hardware timed, but my hardware was wired wrong. After I corrected the wiring it worked, so that must have been the problem.

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Generating a delayed digital pulse

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Hello again Sdkpark,
Apologies the message I was writing didn't include my full post. Take a look at this great community example for a prebuilt solution to what I believe you're trying to accomplish:
http://decibel.ni.com/content/docs/DOC-5763
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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).
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Hi Frank ,
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Digital external sample clock (C#)

I am using the PCI-6225 card and trying to generate a pair of pulses using the digital lines and internal clock, but I am getting some odd/unexpected results. Can someone explain?
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1. First of all this only did something if the selected clock source was /Dev1/Ctr1Source. No other clock would do, even though there are 2 clocks on the board (e.g. /Dev1/Ctr0Source did nothing).
2. Secondly the waveform timing seemed to be ignored, e.g. leave it out or setting to something other than 1ms made no difference.
3. Thirdly the pulse sample rate also seemed to be ignored, e.g. set it to 1 or 1,000 made no difference.
4. Fourthly the pulse seemed to be spread over odd intervals. Set the integer numberPulseOfSamples as follows
NumberPulseOfSamples   Interval
========================================
1,000                               9 (ish) seconds
2,000                               18 (ish) seconds
4,000                               36 (ish) seconds
1,500                               6½ (ish) seconds
3,000                               8½ (ish) seconds
800                                   7 (ish) seconds
Setting the number of pulse samples to a low value (500) threw an error (-200016, "device memory underflow") when stopping the task.
Can someone shed some light on what is going on and how I can get what I want?

I only seem able to select Ctr1Source, but this may be because (?) I have some clocked analogue input going on at the same time, so perhaps Ctr0Source is busy with this. Unfortunately, the 2 examples of clocked digital wave forms doing a write use PipelinedSampleClock or BurstHandshake, although there are reads using a "SampleClock". If you try to run the 2 examples you get an error
Property: NationalInstruments.DAQmx.Timing.SampleTimingType
You Have Requested: NationalInstruments.DAQmx.SampleTimingType.PipelinedSampleClock (or SampleTimingType.BurstHandshake)
You Can Select: NationalInstruments.DAQmx.SampleTimingType.SampleClock, NationalInstruments.DAQmx.SampleTimingType.OnDemand, NationalInstruments.DAQmx.SampleTimingType.ChangeDetection
Task Name: _unnamedTask<0>
Status Code: -200077
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How do I count digital pulses and convert them to an x-axis unit?

I am a grad student in Chemistry and I have undertaken a project to switch an old spectroscopic instrument from a stepper motor chart recorder to a digital interface.
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Hints:
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Digital pulse on DO line

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What type of DIO are you using? If using a standard DIO-96, you can use the Write to Digital Line function from the standard DIO functions. They are easier to use than DAQmx in this case. Just wire in the device number, channel number, line number, and True to output a high or False to output a low. Once a high is written to the line, it stays high until you write a low. The timing is up to you. You can write a high, wait some time, then write a low.
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How to generate a bipolar pulse train in LabView using USB DAQ 6211?

Hi,
I am setting up a system to generate either a single square pulse or a train of square pulses using LabView, with controls to adjust the frequency, amplitude, number of pulses etc. I have had a lot of help from NI tech support setting up the actual VI itself which seems to be working fine, and outputting the pulses via a USB DAQ 6211 using a square waveform generator and the AO1 channel on the DAQ.
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Hi Shalini,
Apologies for taking a while to get back to you, I hope I can explain what it is that we need to create with the pulses. I understand what you mean about the existing pulses having a positive and negative on the graph - but we need the pulses to start from a resting voltage and the first pulse to be positive, then back to zero, then the second pulse to be negative then back to zero etc. This is to do with reversing the direction of the current between two electrodes to prevent build up of salts on one electrod from the current always passing in the same direction.
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Attachments:
Slide1.jpg ‏38 KB

Using cDAQ timers to repeat a hardware-timed finite-sample pulse train clock

Hi all,
As part of a complex project, I must implement an acquisition hardware interface for a linear motion sensor using the Synchronous Serial Interface (SSI) output common in industrial motion control. (I have a fair bit of experience in digital electronics, but I'm new to hardware timer-synchronized digital I/O in LabVIEW.)
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Go to Solution.
Attachments:
Hardware Timed Pulse Train Clock.jpg ‏102 KB

Hey Ryan,
A picture of the behavior you are seeing would be helpful. The NI 9411 should only be reading 50 bits every 1 ms.
It may not be possible to read 25 bits (do you mean 50 bits? 25 high 25 low) and push it to a queue without encountering an overflow error. If you take a look at the above code the digital input will receive 50 sample clocks every 1 ms. This is equivalent to acquiring 50 points every 1 ms which is an acquisition speed of 50 samples/1 ms=50 kHz. The read loop must keep up with the 50 kHz rate otherwise the buffer will overflow. In the above example I’ve set the read to pull 5000 samples (x) with the assumption that the loop will take less than or equal to .1 seconds (y). This yields a software acquisition speed of 50 kHz (5000 samples/100 ms). If the loop speed is faster than 100ms then the 10 seconds timeout on the DAQmx read will allow for the read to block so the FIFO may be filled.
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ni.com/support

Digital Security - What do You Think?

Here's a thought: what if we used our own digits (ie 'fingers') to make up the digits of our passcode?
So, while it's possible that the hacker may find one or two of our prints, they are very unlikely to find all five of them, and to guess the length of the code, or the code itself.
And I'm pretty sure that the possible permutations will be enormous (in the order of quintillions) if we allow, say, up to 10 digits to be applied in a user specific, digital order.
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Might be of interest to percolate this idea.

Interresting is revoking UTL_FILE from public, which is critical. Also revoke UTL_TCP and UTL_SMTP. This is going to upset an expert I know...Okay, as this is (I think) aimed at me, I'll fall for it ;)
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Gen Digital Pulse Train Finite Retriggerable - Initial Delay is only for first trigger

The DAQmx example Gen Digital Pulse Train Finite Retriggerable has an Initial Delay parameter. It appears (6602 and an E series card) that this Initial Delay only delays the pulse generation for the first trigger. Subsequent triggers show no delay. Is this the designed behavior ? Any way to get the Initial Delay to occur for all triggers ?
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So, yes, you are seeing the appropriate behavior. However, it is possible to get a re-triggerable finite pulse train with an initial delay. What you have to do is set up a re-triggerable pulse, and have that pulse act as a pause trigger for a continuous pulse train. Let me explain further with an example.
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Attachments:
Retrig_Finite_Pulse_Delay.zip ‏135 KB

Usb6211 finite digital pulse

My first post to forum. (So hello : )).
to the point: I want to generate a finite digital signal on one of the digital outputs of USB6211. The signal is a UART frame (8N1) (baud rate can be as low as 100 Hz).
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How can I do this? I appreciate any help.
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Thank you

Hello,
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How to generate a delayed retriggerable pulse using only one counter with PXI 6070E card

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A finite pulse train (N_Pulses >= 2) does require the use of 2 counters on most of our older hardware including your 6070E. If you're just talking about generating a single retriggerable pulse, you would only need one counter.
Here's an example in Traditional DAQ that shows you how to set a retriggerable pulse generation (it also allows you to adjust the characteristics of the pulse on-the-fly).
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Best Regards,
John Passiak

Generate/R​ead Digital Pulse - What clock to use?

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Generate/Read Digital Pulse - What clock to use?