I believe that if you provide a macro name to the OnData property
of the Application object, that macro will run when a DDE update
is made. E.g.,

Sub AAA()
Application.OnData "DoDDE"
End Sub

Sub DoDDE()
' do something
End Sub


--
Cordially,
Chip Pearson
Microsoft MVP - Excel
Pearson Software Consulting, LLC
www.cpearson.com


"chasedan" wrote in message
...
I'm trying to poke a DDE message to RSLINX from Excel based
upon whether a
cell in Excel contains the value 1 or 0. The value in the cell
changes based
upon a DDE link to a timer running on an Allen Bradley PLC
(Micrologix 1100).
I have a macro that can deliver the message but it must be
initiated
manually. Is there a way to launch the macro automatically?