I mentioned this in my initial reply to you, there is a subtle difference.. on Linux people use "block" (..buffered) device nodes to access drives, but BSD's generally use "raw/character" (..unbuffered) devices instead.
As stated in the FreeBSD handbook, block devices don't even exist in a traditional sense anymore:
http://www.freebsd.org/doc/en/books/...ics-block.html
OpenBSD still has block devices, but it's always recommended to use the raw character device, the only exception is when mounting.
Because you're dealing with character devices, you may even wish to trying substituting
dd(1) for
cat(1) when using BSD.