Question of data acquisition

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• motion control for vertical actuator and data acquisition

  Hello

  I am a researcher (a branch of civil engineering) geotechnical engineering and I have very little knowledge about the acquisition of control and data motion, so would need a lot of help from the experts OR. I have only knowledge base on these 2 aspects based on my reading of some materials on the Web site of NOR and youtube videos, so I hope that you bare with me . Here are my questions:

  I am trying to build an actuator which will be used to push a probe (a penetrometer with a load cell to measure the resistance of a soil sample), resembling the concept, photography in the attached file. I need to have these criteria for my system:

  (1) actuator, which can push the probe at speeds between 0.01 mm/s - 300 mm/s with precision and move the probe cyclically (upwards and downwards) in the vertical direction
  (2) load expected on the probe into the ground range: 0.02kN - 6 kN.
  (3) necessary to get the load cell load data and the speed of the probe.

  4) able to control the actuator to a PC (speed and posotion) and monitor data from transducers and data log time even the transducers.

  Guess my beginners is that I will need:

  For orders:
  (1) software - LabVIEW and NOR-motion assistant

  (2) controller - NI PCI-7342

  (3) driver/amplifier - analogue servo AKD Drive

  (4) motor - motor brushless servo AKM

  For the acquisition:
  (1) software - based LabVIEW development systems

  (2) amplifiers or other device - no idea what type on the conditioning of signals

  (3) data acquisition device - no idea what type

  Since I'm a beginner, is - that someone might recommend components (hardware and software) for the control and data acquisition. I'm on a tight budget, so I thankful if someone could help me to recommend components good enough to build my system.

  Thanks for your help.

  At these rates, you will need to run the sensor for the cDAQ.  You can configure the analog output on the Tritex nationally on the position.  There is an adjustable filter that you can set in order to get a clean enough to 300 Hz signal.  When you learn about the Tritex, make sure that let you them know what comms and e/s that you want to use.  If I remember, not all options have worked together.  The analog output may need to be my, but you can put a resistance through the acquisition of input data to get the voltage instead.  I don't remember all the details.  You should really not too much on the Tritex/LabVIEW side.  You will send your movement parameters (beginning of end of race, speed, position, accel, cut), and if you cycle (I believe you) or simply running in a loop.  You could also just be able to use the functions of jog.  When you get close to knowing exaclty what you need, PM me and I'm sure we can work something out with the drivers.  You need only the basics.  In fact, you could probably do this all your movements via digital and analog i/o.

• Digital relay of data acquisition

  Hello

  I quickly ask you questions. Can I connect several relay digital for single block scb - 68 (data acquisition is: 6321 PCI)?

  With Labview, I want to enable or disable each of these relays.  Is this technically possible? because never, I have connected several sensors to scb - 68.

  Each relay acts as a binary switch to a motor brush continuous (3-12 v and RPM motor voltage: 11.5 krm with weight)< 80="" grams).="" the="" dc="" motors="" will="" receive="" power="" from="" external="" dc="" power="" supply="" unit.=""  so="" the="" power="" for="" the="" relays="" (i="" am="" thinking)="" must="" be="" from="" daq.="" but="" i="" know="" daq="" can="" supply="" only="" very="" very="" less="" current.="" i="" am="" trying="" to="" source="" out="" if="" i="" can="" find="" relays="" that="" run="" with="" very="" current="" (which="" could="" be="" supplied="" by="" the="" daq="" itself)="" can="" you="" suggest="" me="" if="" this="" is="" possible?="" and="" also="" any="" information="" or="" source="" for="" the="" required="" digital="" relays="" would="" be="" lot="">

  Thank you

  MSC

  
  

• Configuration of the two of the same model data acquisition

  Hello, community of NOR.

  I'm an intern in mechanical engineering with experience in base with LabVIEW.

  I would like to speak to OR directly on this issue, but I don't have a service contract and my company wants me to understand this before you buy LabVIEW.

  I hope that someone has experience about my question, and I would be very happy to help.

  We intend on purchasing an expansion card for our acquisition of data (OMB-USB-2416), but unfortunately it is offline and no custom would not happen in time.

  So, I need LabVIEW to read voltage HAVE two of the same model of data acquisition, which would amount to about 30 channels.

  Is this possible with LabVIEW?

  Thank you.

  Measurement computing says that the "physical channels" dropdown list is automatically filled in once both devices are configured.

• When I send a 5v of data acquisition, the voltmeter indicates 5V, but when I connect a "normally open" valve Parker for the acquisition of data, the voltage decreases automatically a.14 V. It seems to be grounded. Why is this happening?

  We send 5v data acquisition using a voltage generator. Hook us it up to a voltmeter and see 5V. When connect us the generator voltage to a valve "normally open" parker, the voltmeter indicates .14V. It seems that when we connect the two sons of the valve for the voltage generator, the son act as pattern. We want to control the voltage flowing to tap through Labview. We checked the wires to the valve and they work very well, because if we send a constant 5V since the acquisition of data and put ashore, she, the voltmeter indicates 5V. Someone knows why the son act as pattern and low blood to .14V?

  nsatpute wrote:

  Our data acquisition is NI USB-6259. The valve requires only a 5V max and our DAQ provides up to 5V. However, after connecting the valve to the acquisition of data, the grave tension to almost 0. We start from the principle that the son somehow act as the reason, but we are not sure if this is the case.

  The question here is not how much voltage the valve wants, it's the current needs of the valve.  The 6259 can put only 5mA via an analog output.  Your very likely tap needs much more than that.  If you need to add in an amplifier circuit that can supply more current to operate your faucet.

• LabVIEW data acquisition Setup Multifunction DAQ

  I have doubts as to the acquisition of data in the LabView environment. I used the block diagram (Figure 1) below to review the update of the readings for the execution of a loop.

  Block 1 has been used to enable a task (first steps) with 3 channels (al) analog input AI3 and even set up the channel. In this case, the data bus (data-block 4) are construindos by 4 columns of data (provided by task 3 AI3 more).

  Block 2 is used to set the sampling rate in this case is 1 Hz (1 sample per channel x 1 rate).

  In this case, it worked as I expected (Figure 2). This allows to conclude that the interval between each sample was 1 second. The saw took a second in the iteration.

  The second step was to change the amount of data sampled in accordance with Figure 3 channels in block 3.

  Now, each channel showed 10 samples, while there are 4 channels configured, we have 40 samples. In this case the iteration totalled 10seconds (point to 1 Hz and 10 samples per channel-figure 4).

  The first question is what is the time between each sample obtained by channel?

  In this type of configuration (multiple channels), block 3 provides 10 samples in each channel, as well as the sampling is done, IE, the block gets 3 10 samples from a channel and passes to the next channel or gets 1 comp each channel and repeat this process up to 10 samples per channel?

  What is the best way to make sure that the interval between each sample is constant?

  If anyone knows any text that explains what the function blocks of data acquisition information please.

  Thank you

  Gabriel

  Well, there are several ways to read the signals of multiple signals, and each of them has different behavior. I couldn't see how you get mutiple channels, because in the two codes, you set a channel in your codes. Take a look at this figure:

  

  Here you can see how to set multiple channels using DAQmx, using commas to separate the channels. About the ways different ways that you can read the signals, you can look at the links I sent in my first post to learn more about them.

  In a few words, the time between samples from the same channel is T = 1/Fs, corresponding to the sampling frequency Fs. It is not a rule to determine the interval between samples from different channels, because it will depend on how you did your code, and as I sad, there are different ways to do. You can acquire the samples at the same time, or you can configure your code to read a fixed number of points of a channel and then read another fixed number of samples to another channel (https://decibel.ni.com/content/docs/DOC-28279). You can acquire a finite number of points, or you can acquire all the time. Yet once, take a look at the material that I have already sent. It will help you find the best solution to achieve your code according to your application.

  Kind regards

  Pedro

• How to find the time between two channels of entry in the data acquisition card or pci 6036

  Hello

  I read a lot-related posts on the simultaneous measurement of two input voltage of similar channels in map data acquisition. I know that the best material is "simultaneous measurments of the Series DAQ cards" but I only pci data acquisition card 6036 and I try to understand what is the time between the reading of the two channels . This period is always constant? (must it rely on a voltage (amplitude, frequency, waveform..). I send the sine wave (s) to the two channels and read the values of V, if they read the same value, the difference should always be zero but I get-0,002 to 0.002 Volt difference (I must find a way to convert it in time). A screenshot of my VI is attached. I wonder how I can accurately measure the time delay between the channel.

  I am open to any suggestion, my final goal to read exactly two channels at the same time ((ou connaître le délai exact donc je peux correspondre les données correspondantes étant donné le temps de retard))

  Hi spinup,

  better you should post your question in the forum of LabVIEW, LabWindows/CVI is used

  Good luck.

• do you need a power supply to the current entry with data acquisition or 9265

  Hello I just receive the NI 9265 Daq for research in my lab. I'm trying to present entry and display it on an oscilloscope. I don't get anything. I did some research on the internet, so my question is do you need a power supply to the current entry with data acquisition or 9265?

  Read the data sheet.  Clearly on the first page is a sentence which reads "the NI 9265 requires 9 V to 36 V external power.

• How to change the accuracy of output waveform and spreadsheet graph data acquisition

  See attached vi, data acquisition connects to a waveform graph in a spreadsheet. I want to change the precision of the output of Wizard DAQ 6 decimal places with 2 decimals, but everywhere I looked on the DAQ assistant, I can't find a control accuracy. I missed something? What is the elegant way to do this?

  Thank you.

  Hello sunflower.

  This seems related to this question...

  Why do you want to change the output of the DAQ assistant?

  Should not change the precision of the creation of the worksheet? To do, simply give a few parameters for the functions "to the string conversion..."

  Outside the file save all the other screen precision parameters are just cosmetic measures!

• Conversion rates for simultaneous data acquisition

  I use a Mech multifunction data acquisition. / s/SMU-6366. The maximum sampling frequency for the analog inputs is 2 MHz. Is the time of actual conversion of CDA always 0.5µs, or t - it change with the evolution of the sampling frequency? Can I set the time of the conversion? Reading, looks with peripheral multiplex, you can set convert it clock and the sample separately clock. What is with simultaneous data acquisition?

  Hi Daniel K..

  It is a big question. I wonder if you get any errant behaviour - your card is not up samples as you hope?

  Here is some information that might help you:

  What kind of analog-digital converters are used in National Instruments hardware DAQ Multifunction...

  Wikipedia: successive approximations ADC

  I'm not sure exactly what happens, but dare a guess time digitizing ADC does not vary with the frequency of sampling.  And it will also be more than 0.5 US - it is more than likely faster than that.

  I hope this helps.  Good luck with your application!

• can I use instead of conditioning of analogue output signals data acquisition to provide voltage outputs analog?

  Hello guys,.

  I have a general question regarding the units of packaging such as the USB-9263 analog output signal. If I can use it instead of data acquisition to provide an analog voltage output?

  Thank you

  ELA

  Yes, the 9263 can provide 4 output channels analog voltage (+/-10 v range) with up to 1mA of current drive. Looks like: it refers to the short circuit of conditioning of signals and some protection against overvoltage. Link below is the User Guide:

  http://www.NI.com/PDF/manuals/372406b.PDF

  -AK2DM

• You can trigger through communication Modbus TCP/IP PLC data acquisition without using a loop for?

  Hello

  I am trying to contact a facility through a Modbus TCP/IP communication PLC. I'm new to this method, but the idea is that the installation will send the logical (Boolean) values 1 bit by ethernet to my workstation which read and then will begin data acquisition. Basically, I need a triger to come to my pc. I placed my vi inside a structure case T/F which will run according to the signal, it receives data acquisition. However, for it constantly waiting, I put this in a loop for. The works of vi, but playback signals sometimes lagging behind due to the loop for. If I take the loop out and just run labview permanently, it works perfectly, but I know that the option is only for debugging and should not be used. So my question is, is there a better way to wait for an incoming signal?

  Hello!

  Please note that the order of execution of the write operations on the shared variable 000002 is not determined.

  For example, nothing prevents this order of execution:

  (1) value false 000002

  (2) set to true 000002

  (3) execution of the loop

  In what concerns the delay, you might consider placing a waiting vi in the case of 'false', or the loop uses 100% of CPU if I'm not mistaken...

  Kind regards

  Marco

• Real-time display at the high frequency of data acquisition with continuous recording

  Hi all

  I encountered a problem and you need help.

  I collect tensions and corresponding currents via a card PCI-6221. While acquiriing data, I would like to see the values on a XY graph, so that I can also check current vs only voltage/current / time. In addition, data should be recorded on the acquisition.

  First, I create hannels to analog input with the Virutal DAQmx channel create, then I set the sampling frequency and the mode and begin the tasks. The DAQmx.Read is placed in a while loop. Because of the high noise to signal, I want to average for example every 200 points of the current and acquired for this draw versus the average acquisition time or average voltage. The recording of the data should also appear in the while loop.

  The first thing, I thought, was to run in continuous Mode data acquisition and utilization for example 10 k s/s sampling frequency. The DAQmx.Read is set to 1 D Wfm N Chan N Samp (there are 4 channels in total) and the number of samples per channel for example is 1000 to avoid the errors/subscribe for more of the buffer. Each of these packages of 1000 samples should be separatet (I use Index Array at the moment). After gaining separate waveforms out of table 1 d of waveforms, I extracted the value of Y to get items of waveform. The error that results must then be treated to get average values.

  But how to get these averages without delaying my code?

  My idea/concern is this: I've read 1000 samples after about 0.1 s. These then are divded into single waveforms, time information are subtracted, a sort of loop to sprawl is used (I don't know how this exactly), the data are transferred to a XY Chart and saved to a .dat file. After all that's happened (I hope I understood correctly the flow of data within a while loop), the code in the while loop again then 1000 samples read and are processed.

  But if the treatment was too long the DAQmx.Read runs too late and cycle to cycle, reading buffer behind the generation of data on the card PCI-6221.

  This concern is reasonable? And how can I get around this? Does anyone know a way to average and save the data?

  I mean, the first thing that I would consider increasing the number of samples per channel, but this also increases the duration of the data processing.

  The other question is on the calendar. If I understand correctly, the timestamp is generated once when the task starts (with the DAQmxStartTask) and the time difference betweeen the datapoints is then computed by 1 divded by the sampling frequency. However, if the treatment takes considerable time, how can I make sure, that this error does not accumulate?

  I'm sorry for the long plain text!

  You can find my attached example-vi(only to show roughly what I was thinking, I know there are two averaging-functions and the rate are not correctly set now).

  Best wishes and thank you in advance,

  MR. KSE

  PS: I should add: imagine the acquisition of data running on a really old and slow PC, for example a Pentium III.

  PPS: I do not know why, but I can't reach my vi...

  
  

• How to program dynamically data acquisition?

  The question may seem, I want to dynamically change the settings of a data acquisition card (DAQmx). The idea is to have a loop event caputures GUI and the other while answering the while loop DAQ events. It's something like loops PRODUCER-CONSUMER. However, I can do all thing once, but not on the fly. Any suggestions as to how we can achieve this?

  Thank you

  Thanks for the comments. I solved the problem with the traditional approach. Here is the graphic interface to work.

• not able to write the data through data acquisition

  Hello

  In fact, I need to send a code word (text file) from the program matlab through my data acquisition (OR-USB-6215). my program (transmitter.vi [case structure: page2]) attached below has a problem to do the task. whenever I run the program it gives me an error like

  Error-200479 occurred at DAQmx start Task.vi:2

  Possible reasons:

  Measurements: Specified Operation cannot be performed during execution of the task.

  Task name: _unnamedTask<84>

  At the moment I don't see output in my oscilloscope. But, if I highlight my performance I observe my samples on the oscilloscope with the following error message

  200288 error has occurred in the DAQmx write (analog 1-d 1Chan NSamp DBL) .vi:3
  Possible reasons:

  Measurements: Attempted to write a sample beyond the final sample generated. The build is stopped, so the sample specified by the combination of the position and the offset is never available.

  Hi Raja,

  What I did is I moved the 'write DAQmx' outside the while loop. That made the VI in this case is read the file and passing it to a table, and then this table is formatted a waveform to be written to the data acquisition device.

  With respect to the way in which the data is read, I don't change anything, it was based on your original code. A good way to know if you write the correct data is to check the chart view in VI.

  So the question is, is the graphic display showing the good waveform?

  Best regards

  Faris