Ben,
Unless you have a good reason that requires more than one instance of Excel
use the single instance, as the other replies have suggested.
However if required, you can use GetObject to return a reference to an Excel
instance, but you cannot be sure which instance you get; it is determined by
the OS and should be considered random.

Peter T has written about this a few times
http://groups.google.co.uk/group/mic...50af98 b97529

However, as it seems you have the Path/Filename, this should do:
http://groups.google.co.uk/group/mic...78af9f b56ca8

NickHK

wrote in message
ups.com...
Hello,

I know how to open another workbook in another instance of Excel and
run a macro:

e.g.
Set xlApp = CreateObject("Excel.Application")
Set wbChart = xlApp.Workbooks.Open(filename:=ThisWorkbook.Path &
"\chart.xls")
xlApp.Run "chart.xls!mcrUpdateES", dteClose_15, dblHI_15, dblLO_15,
dblLast

But how do I do this if the workbook is ALREADY OPENED in another
instance of Excel? I think the problem centers on how to identify the
seperate instance of Excel that is already running. i.e. it's easy to
know that "xlApp" refers to the seperate instance if I'm creating that
instance at run-time, but how to refer to the seperate instance if it
was created before run-time.

Any help greatly appreciated.
Ben.