How can I make waveform graph and/or excel file with two different dynamic DBL values?

Question

As the question describes, I have two dbl sources from a load cell and linear actuator (from firgelli). I want to make a load/displacement curve from the force readings from the load cell and the displacement readings from the linear actuator. The load cell outputs an analog signal that can be acquired by a DAQ and the actuator comes in with a board and VI program to control the speed and measure the displacement of the actuator to a sample rate of my choosing. Is there a way that I can make a VI where it continues to collect data and construct the graph I'm looking for?
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Answer 1

A couple points about your application:
1.  Synchronization.  Since you're ultimate goal is a stress/strain curve, it is vital that your force and displacement data be synchronized appropriately.  If your sampling is beyond a few times a second, this is not really possible without some form of hardware synchronization via either a trigger and/or sample clock.  Two NI DAQ boards can be synchronized this way easily, but it seems you're using 3rd party hardware for one of these processes.  Would need to know more about that board to know what options you have.  You could specify what your resolution is in distance, and how fast the article will be moving, to get an idea of how fast to acquire, and how well you'll need to synchronize the data.  Another option, since it appears each data stream will be sampled on a hardware-timed sample clock, they will be offset in time, but not skewed during the acquisition.  You may be able to identify a feature in the data set common to each and use that to remove the timing offset after the process is completed.
2.  Display.  To display data during the acquisition process, I usually recommend at least one display that plots vs. time.  Much easier to spot irregularities with the acquisition process that way.  However, if you'd like to also plot force vs. displacement, you can use an XY Graph to plot parametrically. For Example, in your case you would use the Displacement data as the X coordinates, and the Force data as the Y coordinates.
3.  Saving data to file.  I would recommend using the Save to Spreadsheet File.vi (File IO pallette) to save your data.  If you use a comma as the delimiter, and save the file with a *.csv extension, you will have a file that is easily read into excel.  The standard tab-delimited spreadsheet file is also fine, it will just require an extra step to read it into excel to specify to excel what the delimiter is.
4.  Batch vs. Real-Time Recording (Data File).  If your process is short (< 30 sec) you may be better off acquiring the data, Storing it locally to the VI (Array - usually maintained in a shift register), and then writing the file with a header (acquisition parameters, test article information, data column headers) and the data all at once in batch mode to the file after the process is finished.  If, however, it is longer than that you would be better off starting a data file with a header and appending the data to the file as you go, so that if something happens during your test, you at least have data up to that point.
Hope this Helps,
Kurt