If the reason you need floating point is that your flow totalization generates a very large number, then there do two things you can do:
1. Upgrade your SLC5/03 to the latest firmware, it is not very expensive.
2. Write som ladder code that effectively provides you with double-word sized variables.
Hint: When var1 reaches 10000 and 1 is added to 1, the reset var1 and add 1 to var2.