My PowerCore FireWire control panel shows: "No device found" in Yosemite. Why?
Powercore is not supported in Yosemite. It is not officially supported in Lion, Mountain Lion and Mavericks, even if it works on these OS's. Please refer to this list of support operating systems.
There is a workaround proposed in many forums to make it work in Yosemite, but this is not supported, approved or even tested by TC.
You can find a description of the workaround here: http://www.soundonsound.com/forum/showflat.php?Number=1124739