control design for indentation test

[kingsgambit1943]

Using PZT servo controller (E-516) NI USB-6251 and NI SCC-68 with attached load cell, we want to conduct a creep test.  In order to do so we need the actuator to supply a constant load on the test specimen, which will creep.  Ive written the outline of the program in labview 8.5, but it still needs some work. When I run the program 1st I establish initial contact at the "user load", the user load is also the constant load we will like to supply in the future.  After initial contact you would run the creep test.  Here are where problems occur.  Ive only been able to get 1 point plotted when I run the program, leading me to suspect that I did something wrong with the plotting portion of the program or simply used the XY plot function incorrectly.  The values used for comparison that bound dp are arbitrary as i have changed them around a bit to try and get the plotter to work.  

Any suggestions on how to improve my code or any hints or tips around control design is appreciated.   This is like my hello world to labview.  I understand that my method is very primitive but given my limited knowledege this is what I came up with. 

thanks for the help 

[Alain_S · Accepted solution]

I think this will do 🙂

In the mean time i cleaned up some wires 🙂

I hope that element 0 of the array "Current PI Position" contains the correct postion.

[kingsgambit1943]

Thank you very much

I just have a question about the property node value, what does it do ?  I dont really get these property nodes they seem to encompass a variety of abilities.  Thats it, again thank you very much.

[Alain_S]

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kingsgambit1943 wrote:

I just have a question about the property node value, what does it do ?  I dont really get these property nodes they seem to encompass a variety of abilities.

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In nature you have horses & zebras. Quit the same but not 100%

In LabVIEW you have local variables & property nodes. Quit the same but not 100%

Local variables uses more memory because it takes a copy of the control, but are faster.

Property nodes uses less memory but are slower.

Check this forum, lots of threads regarding local variables vs. property nodes.

I'm sure other people can tell you much more about this... ...