Problem calling function in DLL via NETLink: NET::netexcptn: A .NET exception occurred
- To: mathgroup at smc.vnet.net
- Subject: [mg66319] Problem calling function in DLL via NETLink: NET::netexcptn: A .NET exception occurred
- From: Heiko Damerau <heiko.damerau.news at web.de>
- Date: Tue, 9 May 2006 02:35:24 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello,
I am trying to call a function in an ordinary C++ DLL (should be
well tested, not my code). The DLL function I am calling is declared as
short SyncRPC FAR PASCAL SyncRPC(const char *locName, const char
*locProperty, const char *locCycle, short ArraySize, void *Data, long
DataSize, short DataFormat, short DataType)
As I do not need the full flexibility when called from Mathematica,
it is defined as
DLLFunctionSyncRPC = DefineDLLFunction["SyncRPC", "rpcapi32.dll",
"short", {"char*", "char*", "char*", "short", "byte[]", "byte", "short",
"short"}];
and finally called by
DLLFunctionSyncRPC[elementName, property, plsLine, optArraySize,
netManagedDataArray, 0, 1, 0];
where elementName, property, plsLine are Mathematica strings,
optArraySize is an ordinary mathematica number (integer) and
netManagedDataArray is a .NET object declared as
NETNew["System.Byte[]", 17optArraySize + 1];
to get the pointer to the result. Everything works fine but sometimes I
get strange error messages:
NET::netexcptn: A .NET exception occurred:
System.NullReferenceException: Object reference not set to an instance
of an object. at
Wolfram.NETLink.DynamicDLLNamespace.DLLWrapper612.SyncRPC(String ,
String , String , Int16 , Byte[] , Byte , Int16 , Int16 )
and my notebook is not executed as it should. Changing nothing and
just running the Mathematica notebook a second time and the error
disappears most of the time. The error appears especially, when I call
the DLL function extremely often; but also with a fresh kernel the error
normally comes after some 25 calls of the function in the DLL.
It would be great if anyone could give me a hint what is wrong with
my function calls, because most of the time everything works correctly.
Thanks a lot for any information in advance.
Best regards,
Heiko