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DAQ timing

March 14, 2014, 3:14 pm
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Hello,

 

I am getting data by DAQ Assistant in a While loop. I need the loop working just for 600ms and after that it should stop. I used two Tick Counts inside and outside of the loop (just like attached) so that as soon as x-y indicator gets 600 the while loop should stop. However, this idea does not work as x-y never gets 600. It always starts from around 1025ms (it is randomly, some times this number changes to 1041, 1023, 1058,...). Does any one know what is the problem here? Some thing is wrong with my DAQ Assistant?

 

Thank you

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USB-6251 power(+5V) LED is not solid but blinking when turned on

March 17, 2014, 9:41 am
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Hi all

 

I have been using USB-6251 for 3 years without any troubles until last week.

 

From last Thursday, when I turn on the board, power led (which is located on top, also written as POWER(+5V) ) starts blinking and my laptop doesnot recognize the board.

Before this issue, when I turn on the borad the power led was solid and my laptop automatically recognized the board.

 

I would be glad if anyone can help me to know what happend to my board.

 

Thanks!

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6250 +accelerometers to TDMS files - timing calculations?

March 17, 2014, 7:55 am
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Is there a way to calculate time differences in TDMS files between a set of 5 accelerometers and when they activate? Our set up is:

  1. Meggitt accelerometers 5 pieces - 2255B model
  2. NI PCI 6250 data acquisition board
  3. Driver package – NDQX 9.5.3
  4. Software settings are: sample record 1024; channel gain 50; Trigger level 1; samples per second 2000; trigger delay 500
  5. TDMS file generated

So, we can count the cycle differences in the waveforms. Can they be calculated back to time so we can get time differences. Any ideas?

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fast AI and DO using usb-6215

March 18, 2014, 2:53 am
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Hi everyone!

I'm trying to use a usb-6215 to aquire a 50 hz signal, and at a certain point on this signal trigger a digital out to kill the signal. As the accuracy is of importance where just a few degrees can differ, timing from AI to DO needs to be in the range of tens of micro seconds. So, my question is thus, is the 6215 too slow for this task? 

I've asked this question in a thread before, where it was implied that it was too slow but just wanted get this confirmed by others before ordering new hardware.

 

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How can I name all my DAQs the same so they are universal across PCs?

March 18, 2014, 4:42 am
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I have two usb daqs from NI, and they are currently labeled Daq1 and daq2, the problem is that each works only with a specific program sicne the daq assitant is only configured to one. I tried to configure it to both but got a does not support multiple devices error. What I want is to take any DAQ plug it into any PC I have running my program and have it work. Both are collecting the same data and both programs are otherwise identical.

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PXI 6289 Accuracy Calculations

March 18, 2014, 2:47 pm
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I'm trying to calculate the absolute accuracy of a 6289 reading using the formulas in the spec. In looking at the example on page 5 of the NI 628X specification the number at the bottom that is calculated for absolute accuracy is 980uV. Is that +/- 980 uv?

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HITEC servo control with NI-USB 6351

March 19, 2014, 8:18 am
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I have a servo motor from HITEC (model HS-805BB) and the multifunction DAQ card NI-USB 6351. I would like to use the counter/timer terminals of the card in order to send a PWM signal to the servo and control its motion. How should I make the connections? Do I need to have an additional circuit to provide more current to the motor?

 

I am very new to motor control, especially when it comes to electronics.

 

Thank you!

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using a cDAQ 9184 in a project

March 19, 2014, 9:51 am
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Hello:

 

Currently I am using a cFP-2200 with multiple modules. i had to improve the performace and signal collection for a load cell, analog Input need more speed. I purchase a cDAQ 9184 with a NI 9205 Analog Input and Load cell.  I can see the Network Devise in Max and it shows the cDAQ 9184 and both modules, I can test all the inputs and read data just fine using the test inputs.

 

I am using LabView 2012 with the latest pack (or update). No I have not updated to LabView 2013, I do not like make those type of changes in the middle of project once the project is completed I will do so.

 

I can not add the cDAQ 9184 to the project list I does not show in the list of Target Devices, I have look for it in intire list.

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Generate voltage with a trigger configure

March 19, 2014, 10:55 am
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Hi, everyone

 

I want to ask a general question about the data generation process.

I used "DAQmx start digital edge" to configure the task to start generate voltage on a falling edge of a digital signal in my application.  My trigger is a pulse train with a trigger freqeuncy 10Hz. Does the generation process stop at the rising edge? Or This is just effective when the first pulse appears and then the signal is generated continuously?

 

Thanks!

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END OUTPUT CUTRE

March 19, 2014, 3:28 pm
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Hello, everyone

 

How does a " End Output Cutre.vi" work when it is right after a " DAQmx clear task.vi"?

 

A part of block digram is shown.

 

Thanks!

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read from measurement file make slow the while loop

March 19, 2014, 7:25 pm
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Hi there,

I'm using Labview to control a lower limb orthosis. What I did is to record in a spreadsheet the values of the two angles in a random walk. The control model is made well because I tested it by giving two sinusoidal waves with different frequency and the system responds by following the trajectories. The problems start when instead of the sinusoidal waves I put the experimental values of the angles reading it with the "Read from measurement file". I can't vary the speed of the system by varying the timing of the while loop. The speed is always the same.

 

In the attached vi is possible to find this part in the upper left corner of the while loop. 

I'm using windows 7, labview 2013 and cDaq-9178.

 

Thank you in advance for the reply.

Best,

Flavio

 

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regarding labview application

March 19, 2014, 11:57 pm
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hello to everyone.

              i am facing aa problem in which i have a main vi and sub vi. whenever i  try to control the main vi remotly using web server in internet explorer the main vi works very well but sub vi does not execute after pressing the button from which sub vi is assosiated.

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aperiodic acquisition analog signal

March 20, 2014, 4:26 am
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dear sirs,

excuse my English, it is not my native language but I cannot get help from the forum in my tongue.

I have folllowed 2 LABVIEW courses but have not been taught on DAQmx acquisition. I am using LABVIEW2011, a NI 6229 PCI card/CB68LP connector and I want to acquire an analog signal that should be considered as non periodic.

A motor is spindling at 20Hz nominal with an uncertainty of 20%. 2 sensors ara attached to this motor and send digital signals :

S1 -> 1 signal per rotation, reliable (f1~20Hz)

S2 -> 1024 teeth in 1 one revolution (f2~1024*20Hz) but must consider missing teeth possibility

The analog signal must be acquired during 20 or 40 periods (counter on S1) on each falling edges of S2 and I want to store each value with the corresponding time (relatively to the start of the acquisition) in microseconds and the counter index on S1. Is it possible to do so without switching to LABVIEW RT?

I have succeeded in acquiring an analog signal from a function generator but am unable to go further.

Any help would be welcome on DAQmx assistant configuration regarding those points :

- should Dev1/ai0 analog be triggered by S1 or S2 PFI inputs, reference trigger? advanced timings parameters?

- counter input/edge count on S1?

- digital/line input for S2?

Thanks in advance for your help,

 

Pierre

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bonjour,dans VI logger lorsque je fais un run task,j 'ai ce message qui apparait

March 20, 2014, 9:23 am
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task validation

 

ERRORS

Database does not ecist in the specifield path

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NI9205 used to measure voltage Kulite sensor

March 22, 2014, 6:38 am
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Hi everyone,

 

I'm working on a project for the university. It's an axial compressor and we need to measure high frequency pressure at some places.

 

We are using this sensor: Kulite XT-190-25A (datasheet: http://www.kulite.com/docs/products/XT-190.pdf)

These sensors have 4 pins, two for the outputs and two for the inputs. I'm using an amplificator : Dataforth SCM5B38-07 (https://www.dataforth.com/catalog/pdf/scm5b38w.pdf)

 

I have a NIcDAC9178 with a card NI9205 to read the voltage of the sensor.

 

My problem is the following one: when I connect the sensor to the board, I'm not able to see any variation of voltage... Even if I blow on the sensor , nothing.

 Do you think it could be a problem on my board, or is it my connections?

 

Thank you in advance for your help!

 

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how to output multiple scan in usb6008 with matlab

March 23, 2014, 10:18 am
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hi
i need your help to use ni usb6008 to output analog signal , the analog signal is the control signal from PID controller i used this code
% Initialization
global  Temperature 
global Irradiance
global current
global Vref
global data
global u
%%get connected devices
d = daq.getDevices
%create session
  s = daq.createSession('ni')
s1= daq.createSession('ni')
  %add analog channel  s.addAnalogInputChannel('ID',channel num, 'measurement type')
% s.addAnalogInputChannel('Dev1',0:3, 'Voltage')%irradiance
  s.addAnalogInputChannel('Dev1','ai0', 'Voltage')%irradiance
  s.addAnalogInputChannel('Dev1','ai1', 'Voltage')%Temperature

% s.addAnalogInputChannel('Dev1','ai3', 'Voltage')%Temperature

s1.addAnalogOutputChannel('Dev1', 'ao0', 'Voltage')
% set rate of scan  1000 scans/second ,  run for 30 seconds

 s.Rate=1000;
s.DurationInSeconds =10
v.TerminalConfig = ' Differential';
%v.TerminalConfig = ' SingleEnded';
%_____________________________
%%
%aquire data and process
lh = s.addlistener('DataAvailable', @plotData);
%store data
%h = s.addlistener('DataAvailable', @storedata);
% Analog Output
ao_value = u % duty cycle control signal 
s1.outputSingleScan(ao_value)

s.startBackground()
   s.wait()
 delete (lh)
 delete (h)
 s.release()

but an error message appeared "The data argument must contain one column for each output channel in the session.
" i also can't use queue output data
ao_value = u % duty cycle control signal 
s.queueOutputData (( ao_value)'); 
it gives me error that "There must be at least one analog output channel in the session before outputSingleScan or queueOutputData can be used.

 

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cDAQ 9174 USB Device Not Recognised (NI 9425, NI 9476, NI 9239, NI 9263 modules included)

March 23, 2014, 6:40 pm
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Hi,

 

I have a confusing promlem and I am very close to be crazy because of that. 

 

The problem is that my cDAQ 9174 usb device is not detected by computers. (but sometimes do)

 

1) It had been working for two years normally.

2)Then, one day computer1 (win 7, 32bit) didnot decected it. I try to restart computer and it worked.

3)day by day, i experienced this problem more frequently.

4)then, i decided to change my desktop computer because this problem causes some breakdown.

 

all confusing problems started after that.

 

 i bought a new HP computer with i3 processor and win7, 32bit. this computer did not detecet my daq card anyway. 

 

As a result, I tried to connect this device with 5 different computers. (device manager and labview are installed into all computer in same way.)

 

Results:

Computer1(win7,32bit): Its orginal old desktop computer, It somtimes detects but it is not reliable.

Computer2(win7,32bit): Its new HP desktop computer, It never detects.

Computer3(win7,32bit): My personal laptop, It always detects, there is no detection problem.

Computer4(win7,32bit): My friends laptop, It never detects.

Computer5(winxp,32bit):  A computer of a working system with NI USB 6211, It somtimes detects but it is not reliable.

 

 

Now, is there anyone who can help me? Please, it is very important.

 

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Debugging of VI to read from Force Sensor and RPM Sensor simultaneously

March 23, 2014, 7:28 pm
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I have a VI (attached below) which reads the voltage values from an ATI Force/Torque sensor, as well as to count the frequency of an optical RPM LED signal. My objective is to synchronize the logging of data from both force and rpm sensor, such that the data captured at every interval is at the same time step for both sensors. My program for measuring the RPM sensor data has some bugs as it does capture data continously, but only once. I tried using a while loop but ended up with an error. I have no experience in LabView, and appreciate any help or advice given.

 

Thank you!

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Problems with aquiring DC Voltage with PCI6229 on a board with Intel Q87 chipset

March 24, 2014, 4:41 am
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Greetings,

 

I have a big problem with the aquisition of a continuous measurement of a voltage using the PCI6229 on a board with an Intel q87 chipset (D3231-S11 Fujitsu Siemens).

 

I developed a program, which only needs to measure the Voltage of an analog input of the  PCI6229 card.

 

When i switch the mode from 1channel 1sample to 1channel Nsamples, the program crashes (the whole PC crashes and only a hard reset works) Taskmanager didnt stop the task.

 

Even the DaqMX testpanel crashes, when i switch from 1channel 1sample to 1channel Nsamples.

 

On other systems with different chipsets the software works fine.

 

Is there a known Problem with this chipset and the PCI6229 Card ?

 

with best regards

 

Tobias Lembke

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USB 6501 DAQmx Timing and DAQ Trigger

March 24, 2014, 7:02 am
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Hi, 

 

I am wondering if I can capture a hardware trigger using NI USB 6501. The trigger signal is perodic with following features. 

 

The duration of 0 is 200 nano second. 

The duration of 1 is 100 micro second but sometimes 50 micro second. 

 

So, NI USB 6501 can capture the above mentioned trigger ? 

 

Do I need to use of  DAQmx Timing and DAQ trigger ? 

 

Best regards, 

Bilal 

 

 

 

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