Passing data between BlitzMax and a Max dll?

-- EDIT : I got it working --

The plugin return a bank buffer. "databank:TBank" is a global variable, so the dll GC routine shouldn't delete it:

Function PluginImport:Byte Ptr(HFile:Byte Ptr)
	GCEnter()
	databank=createbank(4)
	... ... ...
	Return databank.buf()
EndFunction

The main program creates a static bank from the buffer:

datapointer:Byte Ptr=PluginImport:Byte Ptr(HFile)
databank=CreateStaticBank(datapointer,4)