Setting the Environment Variable
To enable the plug-in to find the location of the XSB binary, you also need to set the respective environment variable in your operating system. The variable to be set is XSB BIN DIRECTORY and the value is the path of the binary. Note that the variable must not point to /pathToXSBFolder/XSB/bin/ but rather to /pathToXSBFolder/XSB/config/ARCH/bin/ where ARCH is an architecture-dependent directory name.
To set up the environment variable under Windows 7, follow the information presented in Sect. 2.7 of this document.
The document also contains information on Linux and Mac.
For Mac, note that the indications only work when running Protégé from the Terminal. To properly set the variable for directly running the application (not via Terminal) please consider the following:
Environment Variables and Mac 10.8 Mountain Lion
Environment Variables and Mac 10.7 Lion (there is a typo in this document - the file to be created should be 'environment.plist'.)