To run multiple versions of the System Generator, all intended installations must be compatible with the associated MATLAB version.
When there are multiple installed versions of the System Generator, you can run the xlVersion script from the MATLAB console to change versions of the System Generator.
ISE 10.1 Software and Newer
Starting with the ISE 11.1 software and later, you can run the "MATLAB chooser" program for the version of System Generator you want to use from the Start menu under "Xilinx 11.1 > DSP Tools > Select MATLAB version for Xilinx System Generator".
Prior to the ISE 10.1 software, the MATLAB Chooser was not available, therefore, you must use xlVersion to return the software version number.