Invoke node (parallely working VIs in a library)

Question

Hello everyone,
I am trying to evaluate a temperature sensor.To do that I have to monitor thermocouple readings.Thermocouple is connected to FP-TC-120 temperature module. Besides, I have to acquire data from an optical spectrum analyzer. I am using 3650.VI to monitor the temperature and 86140B Trace_Screen Capture(2).llb o trace the data from the OSA.
I am trying to use Invoke Node VI to trace data from spectrum analyzer. To do that I specified the necessary file path as an input to the code. The problem is the necessary VI (Write Trace to File.VI) is inside of a llb. file and needs other codes to completely function.
That's when I run the code, (and when the stability condition is met) the computer asks me to save the spectrum analyzer data to a file called trace.csv. When I press ok, it just saves an empty file with a header (Power(dbm) Wavelength (nm)). Apparently it works parallely with other VI. How can I make use of the VIs inside of a .llb file with invoke node VI or should I use other VI to do combine temperature monitor VI with data tracing VI.
The second problem is with the stability criterion of temperature.In the attached VI, I check whether the thermocouple reading stays within 0.8 degree stability range for 900 seconds. I want to change this. I
want to check the stability of the temperature by comparing the final data with the previous ones. Is there any specific VI that should be exploited to check the fluctuations of waveforms?
 Thanks a lot
Solved!
Go to Solution.
Attachments:
3650.vi ‏107 KB
86140B Trace_Screen Capture(2).llb ‏143 KB

Answer 1

deniz wrote:
I tried to implement the first method you suggested. But i had trouble since I am just a beginner. Could you please be more specific in explaining the solution? I am stating the problem again. Once the stability criterion is met I want the case structure to execute on the increments of 30 second or so. How can I do that by using shift registers? I tried to do  what you suggested as in the code attached but it did not work. (I could not make the case structure dependent on two conditions)
I understood what you wanted perfectly fine. You just didn't implement it correctly. See attached. Please revisit my comment regarding the Write To Spreadsheet File that already exists inside of the "Trace Xfer" VI.
The other proplem is again about timing. The while loop execute only if the temperature value changes since it is dependent on FP Open sub VI.
The while loop has no dependence on the FP Open VI other than waiting for the error cluster and Fieldpoint refnum. There is no dependence on the while loop executing only if the temperature value changes. The while loop continuously acquires data, so I do not understand your statement. 
Thus, the elapsed time VIs that are inside of the loop does not progress at 1 second increments. Is there any way to set an elapsed time  that is independent of timestamp of thermocouple reading device? 
They can't and won't. The Elapsed Time VIs simply tell you ... elapsed time. They have no bearing on how fast the loop runs. It seems as if you have contradictory requirements. Do you want to the loop to run once a second and record, or run at the advise rate and only do something once a second, or run at the advise rate and only do something if the temperature changes?
Attachments:
3650.vi ‏116 KB