Use VBA In Workbook A To Perform Actions In Workbook B

I was asked to parse and chart some data files. The data are obtained from a data acquisition system sampling a pressure transducer at about 300 samples per second. Since the start of the pressure event is created by a chemical reaction, there is no easy way to gauge when the the event will begin. As a consequence, the data acquisition system is left running continuously while waiting for the event.

Needless to say, at 300Hz, the data file grow very large, quickly. The data preceding the pressure event are close to zero and can be removed simply by using code which deletes rows with values less than a given threshold. An example of this code is:

Code:
Private Sub CommandButton1_Click()
Dim rng As Range, cell As Range, del As Range
Set rng = Intersect(Range("B20:B500000"), ActiveSheet.UsedRange)
For Each cell In rng
If (cell.Value) < 0.15 Then

[Code] ....

There are other operations that need to be performed as well. My question is whether if I have a workbook open with this and other code, will Excel allow operations on one or more open workbooks from this workbook? I would think that you can because you can move or copy a worksheet to another open workbook.