def ToFloat(data):
    s = data.decode('utf-8')
    print(s)
    return s

In [3]: import struct
In [4]: struct.unpack('h', b'xc8x00')[0]
Out[4]: 200

import struct

def to_float(data):
    return float(struct.unpack('H', data)[0])

data = b'xc8x00'
def ToFloat(data):
    byte0 = int(data[0])
    print(byte0)
    byte1 = int(data[1])
    print(byte1)
    number = byte0 + 256*byte1
    print(number)
    return float(number)