Loadlibrary / Declaring dll function at runtime

My software uses a Can serial card. I need to support three different types of card (PCMCIA, PCI, USB) each of these have there own dll. The dll's all contain the same function / function names.

At the moment I have to get all the users to rename their dll file to 'cancard.dll' then I am using:

VB Code:

Declare Function CANPC_reset_board Lib "cancard.dll" Alias "_CANPC_reset_board@0" () As Long

to delcare the function(s).

I want to get away from forcing the user to rename their DLL's and automatically detect their dll and delcare it at runtime.

I briefly looked at LoadLibrary, but it appears you need to use CallWindowProc to call the function. I still want to use the same syntax as before e.g

VB Code:

dim err_code as long
 
err_code = CANPC_reset_board

Any ideas?

Cheers

Create an alias for each dll and call the appropriate aliased function at runtime.

Have you got an example of how to do this?

Cheers

VB Code:

Declare Function CANPC_reset_board_pmcia Lib "cancard.dll" Alias "_CANPC_reset_board@0" () As Long
Declare Function CANPC_reset_board_pci Lib "cancrd2.dll" Alias "_CANPC_reset_board@0" () As Long
Declare Function CANPC_reset_board_usb Lib "cancrd3.dll" Alias "_CANPC_reset_board@0" () As Long

Note that I don't know what the real names of the dlls are - you'll have to edit that..

Thats an idea, though they would normally only have one of the DLLs one their PC so the other declares would cause an error.

Actually it might work, the declarations don't cause an error unless I call the function and the dll doesn't exist. I can check which dll exists at runtime then use this:

VB Code:

private const PCMCIA = 1
private const PCI = 2
private const USB = 3
 
private cardtype as byte
 
public function CanPc_reset_board() as long
 
select case cardtype
case PCMCIA
   CanPc_reset_board=canpc_reset_board_pcmcia
case PCI
   CanPc_reset_board=canpc_reset_board_pci
case USB
   CanPc_reset_board=canpc_reset_board_usb
end select
 
end sub

Just trap the error and use it to determine that the dll doesn't exist, maybe?