Retaining a calculated value for iterative calculation

[bunnykins]

Dear LabVIEW Forum Members,

This may appear to be a trivial question however I am having difficulty trying to solve this problem using the LabVIEW vi's & environment.  I explain as follows:

I need to calculate and display, in graph form, the contents of a Hopper that is initially filled to 100 tonnes.  The hopper is being discharged and filled at the same time, I have the values of filling and discharging in 1 second intervals.  The contents of the Hopper is a simple mass balance calculation, Hopper Contents = Inlet material - Outlet material.  Below are the first few data sets:

Material Into Hopper         Material out of Hopper        Theoretical Hopper contents

               0                                     0                                                 100

               0                                     1.534057                                   98.465943

          0.345                                  5.250186                                   93.560757

          0.6                                       6.801075                                   87.359682

How can I iteratively calculate and use the 'Theoretical Hopper contents' calculation from the Hopper inlet and outlet ?  I am using the Simulation & Control Frame so I cannot use the For Loop within this frame.  Attached is me vi program so far and the Build XY Graph2 is where I'm wanting to display this Hopper contents data.

Any help would be gratefully appreciated.

Regards,

[Brad_Turpin · Accepted solution]

Hi bunnykins,

You've asked a LabVIEW question on the DIAdem Discussion Forum.  Please repost to the LabVIEW Discussion Forum.

Brad Turpin

DIAdem Product Support Engineer

National Instruments