Need Labview 8.0 to recognize Omega Personal DAQ 55.

[DBFIU]

Hello,

  I am new to Labview. We are trying to instrument a turbo-jet with data logging capability, K-type TC's,  pressure transducers and load cells. We purchased the Omega OMB DAQ 55 and downloaded the Personal DAQ driver.

I want labview to recognize my hardware and log all data using this device. Here is a thread on this topic, but it is short and is not very helpful.

http://forums.ni.com/ni/board/message?board.id=170&message.id=180589&query.id=209671#M180589

In that thread, Tom Bosch says he installed 'something in the wrong directory'. What is he referring to, and which directory did he end up installing it in?

If anyone has any experience with the OMB-DAQ-55 please respond. I am an undergraduate engineering student who will be graduating in a month, any help is greatly appreciated.

   - Dan

[smercurio_fc]

I believe what that post is referring to was simply where to place the VIs that the manufacturer provides to talk to the device in LabVIEW. Omega provides LabVIEW drivers for that device. You can install these driver VIs in the "instrlib" directory within the main LabVIEW installation directory (by default "C:\Program Files\National Instrument\LabVIEW 8.xx\instrlib"). If you look in that folder you should see some pre-installed with LabVIEW. That basically just creates an item in the block diagram palette to provide quick access to the VIs. The VIs can actually be anywhere and you can place on on a block diagram by right-clicking on the block diagram, selecting "Select a VI...", and then navigating to the VI that you want.

[DBFIU]

Hello and thank you for the reply.

   Yesterday we got the virtual omega palette to work in labview. But our project will have 5 TCs and 5 pressure transducers and a force sensor. Is there anyway i could avoid using the labview driver from omega (the example files) and just create my own virtual interface with those sensors? There has to be an easier way to do this...

 Much appreciation,

      - Dan

[Dennis_Knutson]

You don't have to use top level example VIs. Aren't there lower level subVIs that the examples call. If so, then you can create your own high level VIs that use the subVIs. Examples are intended to instruct you how the low level functions should be used.

[DBFIU]

Dennis, now I understand what you mean.

Yes there are many low level VI's to work with. I just have no idea where to begin to get this puppy started.

Here is a picture of the high level VI with a bunch of subVI's that you mentioned.

If I attempt the slightest block structure, it will show error. The thermocouples are being read by Labview, but I want to log them and manipulate the data using some functions. If I dont know where the flow of my data is, I dont know where to tap into to stick functions and parallel outputs (i.e graphs, efficiency calculations as a text in real time on the front panel). I just need to know what the heck all this stuff means and how it relates to my hardware, it is very tempermental...

 Sorry for the rant, I am lost but determined to make this work.

Any input is greatly appreciated.

     - Dan

EDIT: Look at the Block picture first. This is a block of the example file included with the omega software i downloaded. The errorout picture is me attempting to make use of this data into some table that can be saved as an xls of some sort. I just want to know what vein i need to hit so that i can manipulate the data with functions.

Message Edited by DBFIU on 11-05-2007 10:47 PM

[smercurio_fc]

The brief example you showed simply has a 2D array of DBLs that is the actual measured values. This data is being sent to the strip chart. The strip chart has a history, so it appends the data at each iteration of the loop.

In terms of dataflow, the 2D array of DBLs is the source of data. You can feed this 2D array into any math functions you want to analyze your data. In your modified version you have the Build Table express VI *outside* the loop. This means it won't execute until the loop is done. Also, since you are only doing a direct tunnel at the loop border, you will only get the last set of measurements. If you want to log all the data you can either:

• Put the Build Table inside the loop
• Autoindex the tunnel where the 2D array is leaving the loop.Autoindexing will give you a 3D array at the output, where each "page" corresponds to an iteration of the loop. Since you are feeding the data into a table you will need to flatten the 3D array into a 2D array.

[DBFIU]

Hello again,

  Here is a more specific question.

  The flow of data in my program is going from the pdaq application block (you can see in one of my pictures above) and straight to a real time strip chart.

My questions are as follows.

Since the data takes the form of a 2-D array, how do I convert it to dynamic data for me to use formulas to manipulate and get some calculated result(i.e engine efficiency).

How do i split up the 2-D array and hook up meters or gauges to the useful values in that array?

Useful info: The real time strip chart shows Temp in Celsius vs iteration. I can see the real time temp in the strip chart by switching on the digital readout in the properties of the chart. I just wish I could access those values for mathematics.

     Please help

         - Dan

[Dennis_Knutson]

The 2D array can be sliced and diced any way you want with the Index Array function. I'm not sure of the structure of the array. Are the rows channels or samples? There is the Conver to Dynamic Data Type function but I don't think you need to do this. For simple math operations, you can simply manipulate the numeric arrays. For example, if a column in the 2D array is multiple samples for a single channel, you can index out that column and wire it to the Mean function. This output could then be wired to a scalar numeric indicator. I never use dynamic data. I prefer to use waveform data types and you would only need ro use this if the analysis functions required sample rate information, such as an FFT.

[DBFIU]

Hello Dennis,

Before I could read your message I had already used 'convert to dynamic data' function and it seems to work well. I split up the signals and then wired each to a thermometer, the run seperately just like I want.

Now that it is in dynamic data i can manipulate it much easier (it seems like everything like dynamic data as an input, i dont know why).

In any case, I will keep you informed as to our progress. Since this type of thing is not very common (interfacing Labview with the omega DAQ-5x series) I will try to be as detailed as possible on my progress.

    - Dan

[Jorge_Gamboa]

Could you please share your VI with me, please share a detailed picture of your application 😃