To resolve issues starting MATLAB on Mac OS X 10.10 (Yosemite) visit: http://www.mathworks.com/matlabcentral/answers/159016
When using Simulink with SimPower Systems blockset (PSB) you have to use a block called "powerGUI".
There you can specify a sample time, when simulation type is discrete.
Still you can choose another sample time or even continuous solver in "normal" simulink 'Model Configuration Parameter' window.
Will there be a cont. or discrete analysis ? What's the difference between those two options ? Why do I need them both ?