You need to find out exactly what the device on the receiving end is expecting before you can start to implement a solution.
It sounds like you figured out that the values must be big-endian singles or doubles. However, you seem to be contradicting yourself in your various replies about how they are to be sent. NetWallah and pryrt have tried to get you to understand but I'll take another go at it.
Does it take a comma separated list of values (like you described with the hex numbers), a single value (so separate packets for each value) or a series of values in some specific format? Perhaps there is documentation that describes said format?