This HowTo includes a step-bystep instruction to compile the mscb.dll from source code in and for windows, including 64-bit. 26.06.2012 by Jochen.Krempel@phys.ethz.ch This instruction provides one way to achieve the target. There may be others. Use MS Visual C++ 2010 (Express) you will need Windows SDK 7.0A for the network-communication (ws2_32.dll) normally it should be included in VC++ (typically C:\Program Files\Microsoft SDKs\Windows\v7.0A ) For building a 64-bit DLL you need additionally "Microsoft Windows SDK for Windows 7 and .NET Framework 4" Version 7.1 If I understand correctly, this can be done from a 32bit system as well (Cross-compile) Create a new Project: "Win32 Project", specify a name and folder. Application type "DLL" ; Option "empty project" ---- in case you want to compile for 64-bit systems: Menu Project\Properties\ Select "Configuration Properties" Click "Configuration Manager" Click the Active Solution Platform list, and then select the option to open the New Solution Platform Dialog Box. Click the Type or select the new platform drop-down arrow, and then select a 64-bit platform. (normally x64) OK, OK. ----- Copy "mscb.c mscb.h , mscbrpc.c, mscbrpc.h , mxml, musbstd" to project folder while maintaining the folder structure (this means mxml-folder and midas-folder) use Menu:Project\Add Existing Item to include all source files *.c and *.h into the project modify the configuration of the project make sure that they appear in "ALL configurations" (not only debug OR Release)! Precede "$(ProjectDir)\midas\include;$(ProjectDir)\mxml;" (without quotes) To Menu:Project\Properties\Configuration Properties\ VC++ Directories\Include Directories Precede "WS2_32.Lib;" (without quotes) To Menu:Project\Properties\Configuration Properties\Linker\input\Additional Dependencies Precede "HAVE_USB;EXPORT_DLL;" (without quotes) To Menu:Project\Properties\Configuration Properties\C/C++\Preprocessor\PreProcessorDefinitions specifically for Windows 7 64 bit with Windows SDK installed in "Program Files" and VC++ installed in "Program Files(x68)" Precede "C:\Program Files\Microsoft SDKs\Windows\v7.1\Lib\x64;" (without quotes) To Menu:Project\Properties\Configuration Properties\ VC++ Directories\Library Directories Menu:Debug\"Build Solution" Search the compiled File in the proper Output Folder (There will be different for Debug, Release, x64\Debug, x64\Release ) You may put the DLL into the folder where your application searches for it. If you want to provide a 32-bit AND a 64-bit version of your DLL, you should read about the SysWOW64 folder. (the 32-bit version goes into there. The 64-bit version (having the same name) goes into the System32 folder. Good Luck