Plotting A Chart From One Variable

[Alectrical]

Hi

I have a variable in cell A1, that I need to plot a histogram of. I need to
create two axis to create a real time chart, where axis one will be an index
value of when the variable in cell A1 changes value, and axis two will be the
new variable value.

Any Ideas would be appreciated.

Thanks
Alec

 

[Jon Peltier]

A chart needs data to plot. You would need some mechanism, probably
programmatic, to record values from A1 as well as times when A1 changes.
These two additional sets of values, stored perhaps in columns B and C,
would form the source data for the chart.

- Jon

 

[Alectrical]

Thanks Jon

But how do I create the mechanism to store the data in columns B and C.

 

[Jon Peltier]

That depends on how the data in A1 is provided. If it's a user-entered
value, you could use the Worksheet_Change event of the worksheet to note the
time of the change in the first blank cell in column B and the new value of
A1 in the adjacent cell in column C. If it's a DDE link, you could use the
Worksheet_Calculate event in the same way.

- Jon

 

[Jon Peltier]

You might need to insert a dummy formula just to ensure there is a
recalculation when A1 is updated, something like =A1 in a cell someplace.

- Jon

 

[David Biddulph]

That's not a charting question. You'd probably be better off asking in
microsoft.public.excel.programming. What causes the value in A1 to change?

 

[Alectrical]

Thanks Again Jon

It is a DDE Link from a PLC that will be providing the variable in cell A1,
in cell A2 I have a timer variable that counts up in seconds, My problem is
creating the code that puts these values in the first blank cells in columns
B and C

 

[Jon Peltier]

Something like this:

dim iLastRow as long
iLastRow = Range("B65536").end(xlup).row + 1
Cells(iLastRow, 2).Value = Range("A1").Value
Cells(iLastRow, 3).Value = Range("A2").Value

- Jon

 

[Alectrical]

Thanks Again Jon

Went to Excel Programming on David Biddulp suggestion.

Been away from my computer for a while, but just tried your code and got it
working on the press of a "button", if I use the Worksheet_Change event excel
locks up because on every change it adds a new line. So I need to modify your
code so that Column B and C are only updated when the variable value changes.

Thanks again for your time.

 

[Jon Peltier]

A simple test:

dim iLastRow as long
iLastRow = Range("B65536").end(xlup).row
if Cells(iLastRow, 2).Value <> Range("A1").Value then
Cells(iLastRow+1, 2).Value = Range("A1").Value
Cells(iLastRow+1, 3).Value = Range("A2").Value
endif

- Jon

 

[Alectrical]

Thanks Jon,

That works a treat, again thanks for your time.

Best Regards
Alec