Excel and LabVIEW in multi-user environment

[GriffinRU]

There are plenty examples on the web and shipped with LabVIEW on how to use Excel. But once you start developing more or less complicated applications you start dealing with sharing Excel instances with other Users, programs and within the application itself.

Below I would like to share my solution to Excel sharing in multi-user environment.

In future it would be really nice if: native LabVIEW Automation Open allows us to request instance by name or ID, not just new or unknown instance.

Built-in Excel features used:

• IgnoreRemoteRequests (disables DDE interface, COM call's still need to be tracked or kept in mind) - to reserve given Excel instance for LabVIEW only
• DisplayAlerts - to leave error checking to LabVIEW only
• UserName - for identification in LabVIEW environment
• AutoRecover -> Enable - for house cleaning purposes

Concept:

A storage VI with 7 modes:

Mode/Command	Description	Usage
List All	Lists all active (obtained by this vi) Excel instances	normal(default)
Open New Instance	Opens new instance of Excel Application	normal
Get Instance by Name	Gets active LabVIEW's Excel App. RefNum	normal
Close Instance by Name	Closes active instance by Name	normal
Close instance by RefNum	Closes active instance by RefNum	normal
Kill All	Kill's all active Excel instances (global process kill command)	house cleaning
Close All	Closes all active LabVIEW"s Excel instances	normal

Simple Example provided.

04/26/2011 Update:

• minor facelift
• "List All" command added

04/27/2011 Update:

• On Exit Excel must be returned to DDE listen state, otherwise it would ignore requests from OS to open documents (Directly still would work)
• Check on instance name collision
• Additional error checking

05/02/2011 Update:

Bug found in Close by RefNum.