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flowmeter on usb 6009 (connections)

April 15, 2015, 4:05 am
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Hello,

 

I am using a flowmeter (attached) on a USB 6009. The wiring connections (3 wires from flowmeter) are:

Sig ground to GRD of the module

+Vdc to the +5V of module

Signal output to the PFI0 of module.

This configuration was already fixed (it works fine with the labview program) by a previous staff member no longer available. 

The question is, in case I get one more flowmeter like this, is it possible to connect it on the same module?? What the wiring connections could be in this case??

 

 Thank you in advance!

 

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DAQmx CreatePulseChannelTimeMethod

April 15, 2015, 6:32 am
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Dear all,

 

I am trying to setup a digital counter using a NI-DAQmx card and using VS-C#. 

 

My question comes when I declare the GateTask. So, I do:

 

GateTask.COChannels.CreatePulseChannelTime("Dev1/ctr0", "Gate",

                    NationalInstruments.DAQmx.COPulseTimeUnits.Seconds,

                    NationalInstruments.DAQmx.COPulseIdleState.Low,

                    recycletime, endtime, realtime);

 

When starting this GateTask the output should be something like:

PulseChannelTime.png

 

When starting the Task it waits "recycletime" seconds low, during the "realtime" counts and in "end time" does not count because it is low again.

 

It seems, though, that it never enters the "endtime" zone, no matter which value I chose for it, it will never take it into account.

 

The question is what it is exactly this low time (endtime) value? Could I generate a Gate task with no initial delay, then a pulse and at the end some waiting time after the next high pulse?

 

Thanks in advance for the help,

 

 

 

 

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counter miss TELL pulses, NI DAQmx 9181 with NI 9402

April 15, 2015, 11:06 am
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Hi,

I am trying to read TTL pulses from a function generator using a counter. I am applying a 1KHz signal to the counter. Every time counter reads the pulses correctly in first cycle of measurement, but it miss some counts in all following cycles.

 

I am using NI cDAQ 9181 Chassis and NI 9402 module with LabVIEW 2014 and NI Max 14.0.

My computer has Windows 8.1 operating system.

 

Please find the attached VI and images of Front Panel after run.

What could be the reason for that, please guide.

 

Thanks !

 

B. Sharma

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Drive CO Timing Off of Non-TTL Clock?

April 16, 2015, 11:41 am
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Hi,

 

I'm using a PCIe-6321. I'm trying to send a counter output for specified numbers of ticks based on an external clock coming into a PFI input.

 

The problem I'm having is that my external signal is not TTL, it is an AC coupled 50 ohm 1 volt signal (+/- 0.5 V about the middle). The voltage difference is too small for the DAQ to notice.

 

What is the best solution to this? Is there a better approach than using an external amplifier to turn the clock into something the DAQ understands (0 - 5 V signal)?

 

thanks,

Isaac

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How to I determine when my Two edge separation counter starts counting

April 17, 2015, 8:08 am
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I've been searching through a ton of Daqmx properties, the, web and the NI-forum to find the answers to the question "How do I determine when my Two-Edge Separation Counter actually starts counting.

 

So I set up my two edge separation counter on two known PFI channels that both trigger when they detect an positive edge.  Now, because i'm using an accelerometer to trigger my first pulse, my concern is that it may possibly be triggered before the test is run.  So I'd like to have labview (if possible) be able to query whether or not the first trigger has been triggered and the counter has begun counting.  If this information is not known, I could run my sample and get a value that is incorrect.  Knowing whether or not the counter has begun counting prior to executing the test, will prevent the operator from running a test, effectively consuming a test item.

 

Thank you ahead of time for any information.

 

-John

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usb 6341 counter number of buffer

April 19, 2015, 9:59 am
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Hi
I will use usb 6341 to measure digital pulse.
What is maximum buffer when i use 25Mhz sample clock with buffered mode?
(It shown error when i set 25Mhz clock, N sample mode, 1M sample)

Is there any fast edge measerement with usb 6341?
(I want ns time scale with long time)

Thx
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USING TWO COUNTERS TO COUNT INDEPENDAN EVENTS

April 20, 2015, 4:40 am
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Hi Group,

Been searching an trying many things to find a solution.  I know there is one but just can't seem to get it right.

 

I have two devices which supply TTL pulses which I need to count.  Ctr 1 will be used as a master clock, Ctr 2 will be used to count pulses from the other device based upon a finite number of ticks from counter 1.

Both pulses are asynchronus, and run continuously.  For instance I want Ctr 1 to read 500 pulses from device 1, and concurrently read pulses from device 2.  Both signals are relatively low freq (<10kHz).  I would like to start and stop both counters with the same clock, but realize this might be an issue with my X Series USB MIO

 

At the conclusion of counting the 500 pulses from device 1, I want end the while loop and read the accrued pulses from both devices.

A little error is tolerable on the second counter, as to it generally being a higher freq than counter 1 source.

 

I'm thinking that the two-edge seperation technique is what's needed, but just can't seem to get there.

 

Help would be greatly appreciated.

Chris B.

 

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DAQ timing

April 20, 2015, 10:52 am
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Hello,

 

I'm trying to make a program that uses a switch to change between a low resistior and a high resistor. The object is to detect when a current has changed significantly to change to a different resistor to calculate the current. I'm using LabViiew 8.5 with a NI 9481 to use for the switch and a NI 9205 DAQ to acquire data. 

 

What I have right now is that the voltage signals are passed through some boolean conditions to determine when the switch needs to be turned on and off. During this time I view the data thats coming from the DAQ. With the circuit that I'm measuring, it frequently goes from a high current to a low current causing the switch to turn on and off repeaditly. So I want to be able to turn on the switch and leave it on for a certain amount of time while I still acquire data. I'm not familiar with using time delays within LabView and this has been difficult for me to figure out. I've attached my VI (sorry for it looking like a mess).

 

Could you please offer any suggestions to overcome this problem? 

 

Thanks

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cDAQ-9181 with NI 9402 : After first read cycle Counter is missing some counts in all following cycles.

April 23, 2015, 10:37 am
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Hi,

I am trying to read TTL pulses from a function generator using a counter. I am applying a 1KHz signal to the counter. Every time counter reads the pulses correctly in first cycle of measurement, but it miss some counts in all following cycles.

 

I am using NI cDAQ 9181 Chassis and NI 9402 module with LabVIEW 2014 and NI Max 14.0.

My computer has Windows 8.1 operating system.

 

Please find the attached VI and image of Front Panel after RUN.

 

I also used the same VI with cDAQ-9171 USB chassis. Result were improved but the same problem still persists.

 

What could be the reason for that, please guide.

 

Thanks !

 

B. Sharma

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single pulse width measurement

April 23, 2015, 12:03 pm
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Hello,

 

I am trying to measure the time of a single pulse using ctr0 on a PXIe-6361.

 

The input signal seen in attachment Capture7.jpg, is going to PFI 9, the gate of ctr0.

The problem is that the counter see' s the rising edge and stops. The pulse width is not given as can be seen in the output (Capture8.jpg).

 

I get the same results using Meas_Pulse_Width.vi example.

Is something wrong with my PXIe-6361?

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Problem using single counter on NI9411

May 3, 2015, 1:43 pm
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I'm trying desperaterly to get 3 Period measurements on a single 9411 module.  I'm measuring ranges from 0 - 5000 hz, I'm able to do this accurately using the high frequency, two counter period measurement method, for two inputs if I read just counters 0 and 2;    What i would really like to do is to get it to work with the low frequency single counter as it appears channel 1 and 3 are not available in this mode in the high speed mode.   What is the minimum period for the low frequency counter, nothing is defined in on line or in the manuals, as to the range of the low frequency?   Even in Measurement Explorer I can't get one low frequency channel to work, I keep getting an error "specified operation did not complete, because of specified timeout expired.

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NI 6023E counter Trigger

May 12, 2015, 4:25 am
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Hi All,

 

I am using NI 6023E DAQ. I am trying to start the analog measurement and the pulse count measurement (PFI8) after the triggering from PFI5.

 

Counters can only be triggered with ARM triggers. But the E series doesnot support ARM triggering method.

 

Can you guys help me in finding the way for starting the both Anlog and Pulse count measurements after the trigger.

 

Thanks in advance.

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How can I increase sampling rate? Active Noise Cancellation

May 17, 2015, 8:44 pm
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Hello

I am an undergraduate working on building Active noise cancellation code.

 

I could make good secondary path filter FPGA code (which could generate maximum 7k sampling rate).

 

However, my second FPGA code (for control filter) can generate maximum only 1.19 kHz. (The control filter FPGA code is attached.)

 

I need 2kHz sampling rate.

 

Since I am using memory storage method for matrix calculation, I think i can't use pipelining.

 

So I tried to increase sampling rate as much as i could by making calculation in parallel.

 

But as i increase the size of the function through parallelizing, compilation gets interrupted due to too much logics.

 

The file attached can generates 1.19kHz and uses 98.7% of slice LUTs.

 

What should i do to increase sampling rate?

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fpga

May 25, 2015, 9:36 am
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Hola amigos, por preguntales como puedo medir el tiempo entre flancos con una myRIO, o con la FPGA que esta en la myRIO, cualquier ayuda sera bien venida 

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CO Pulse Ticks waveform

May 28, 2015, 8:41 am
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Hello,

 

I am using an NI USB-6353 and Labview 2013. I would like to be able to use the CO Pulse Ticks along with the Start Digital Edge functions in order to create a digital waveform graph. My hope is to create a graph that spits out 0s until the edge is triggered, waits for the specified initial delay, completes the specified number of "high ticks" (1s), and then returns to 0s. All I want and need is one pulse. 

 

The code attached already works for what I need it to do and I'm assuming I need to add to it in order to get what I want. Again, I would just like to be able to display a graph on the front panel that displays 0s for low ticks and 1s for high ticks according to the CO Pulse Ticks (with time as the x axis).

 

Any advice would be much appreciated.

 

Cheers

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counter reseting after particular number is reached

June 3, 2015, 11:15 pm
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Hi,

 

I need a counter which will count from 1 to 20. It should reset at 20 and again start from 1 again. Can any one help me in this.

 

Also I need how to interface the labview simulation with real time clock. I mean span of 1 iteration in my simulation should be 1 second.

 

Thanks.

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Problème de pretrig Analogique

June 4, 2015, 5:45 am
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Bonjour,

 

Voila mon problème :

 

Je dispose actuellement d'une carte NI PCI 6254 mais je pense qu'elle n'est pas suffisante. En effet, je veux analyser (enfin du moins capter) 4 impulsion analogique en même temps qui fonctionnent sur le même trigger, mais en analysant aussi la partie de la courbe avant le trigger (donc pretrigger).

 

Comme je me suis rendu compte que ce n'était pas possible d'effectuer cette tache avec la carte d'acquisition citée précedemment, quelle carte PCI me conseillerez vous pour pouvoir réaliser cela?

 

Précisions : la cadence d'acquisition m'importe peu et je n'ai besoin que d'une résolution correcte.

Tout cela pour tester des capteurs de pressions dynamiques piezo (4 en meme temps) en examinant leur reponse pour pouvoir déterminer leur sensibilité et leur écart de linéarité.

 

Cordialement,

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moved

June 8, 2015, 12:32 am
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PXI-6624 custom device

June 9, 2015, 2:26 am
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Hello, Sorry for my bad english. I start with the custom device. I want use two PXI-6624 with Veristand for counter I/O. So I try to creat two easy custom device, one for each card. The program is ok in Labview, the Configuraton/Engine build too. I can interget it, in Veristand without problems. The target deployment is well but I don't see anything in output with an osciloscop. I think it's because of the connection beetween the PXI and the device. You can find, in attached files, the program for one of the two card. It's the more simple of the two device, just two input and two ouput. Thank for your advice
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Fluctuation observed while measuring frequency through "NIDAQmx" library for 6014 PCI card

June 13, 2015, 6:07 am
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We have tried all the APIs mentioned in the attachment for measuring frequency by using NI-6014.Significance difference was observed between the Set frequency and the measured frequency.Please provide the solution for it.

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