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data acquisition - Excel DDE Link: reading and writing in real time


I'm wondering if it is possible to link Excel and Mathematica in real time, so that Mathematica can be used as a computing and "storage" tool. Suppose I have an Excel spreadsheet with an active DDE link:


enter image description here


I would like to know if it is possible for Mathematica to communicate with Excel in real time and store every cell update in Excel. I know there is a package called ExcelLink, with several functions to link Mathematica and Excel. So, if I use, for instance ExcelRead["A2"] I get the correct value



19.36




However, it is not dynamic! I can get dynamic values by using


a=Dynamic[Refresh[ExcelRead["A2"], UpdateInterval -> 0]]
b=Dynamic[Refresh[ExcelRead["B2"], UpdateInterval -> 0]]

However, when I try to add a+b I get



19.36+28.56



And, worse, If I use



Dynamic[a+b, UpdateInterval -> 0]

I get



19.36+28.56



So, here arises my first problem: although Mathematica reads the values in real time from Excel, I'm not able to perform any calculation with them. Is there any way to do it?


My second problem is: how can I write dynamically the values I'm getting from the DDE Link inside Excel itself? I need to write every updated value in Excel in a sequence like shown below


enter image description here



Answer




After some research I've found this partial solution:


Step 1: Open Excel (if you have it!)


Step 2: Open Excel Link


Needs["ExcelLink`"]

Step 3: If you don't have any DDE Link for Excel, simulate real time data using


Dynamic[Refresh[Excel["B1"] = RandomInteger[100], UpdateInterval -> 1]]

Step 4: Import back to Mathematica your simulated data


a = Dynamic[Refresh[ExcelRead["B1"], UpdateInterval -> 1]]


Step 5: Create a numberic list and set Dynamic[] to append sequential numbers to it every 1 second


numlist = {}; k = 1;
num = Dynamic[Refresh[AppendTo[numlist, k++];Last@numlist, UpdateInterval -> 1], TrackedSymbols -> {}]

Step 6: Create a string list (for cell values) and set Dynamic[] to append sequential values to it every 1 second


cellslist = {}; j = 1;
cell = Dynamic[Refresh[AppendTo[cellslist, "A" <> ToString[Last[numlist]]];Last@cellslist, UpdateInterval -> 1], TrackedSymbols -> {}]

Step 7: Store the values in Excel itself!!! (thanks to @rm-rf for the Setting tip!)



Dynamic[Refresh[Excel[Last@cellslist] = Setting@a, UpdateInterval -> 1]]

Result


enter image description here



This is a solution using UpdateInterval->1 . However, I would appreciate any solution with asynchronous reading and writing in real time.


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