thanks for fast reply. as you said I try to write them in a 32 bit memory word.

Are you saying Peter's answer did not work?

The only other twist I can think of is if your power meter is big-endian and your computer is little-endian; or vice versa. See

http://en.wikipedia.org/wiki/Endianness

If that is the case, then instead of copying the four bytes from memory in order, you should reverse the byte order. e.g.

source+0 -> dest+3

source+1 -> dest+2

source+2 -> dest+1

source+3 ->dest+0

in order for the destination computer to properly interpret the IEEE 754 format.