How Could I move Function blocks & variables from one FBD to another ?
You can use import export but sometimes it if the palcement is not taken care of, it will end up replacing your original application. You can follow below procedure if the code you want to copy is more...
Lets say you want to move your logic between source program to destination program. Follow below procedure..
1) Ensure that all connected libraries in source are connected to destination as well.
2) copy the variables (including communication variables and global variables) from source to destination program.
3) copy the contents of "function blocks" tab from source program to destination program and save. ( it throws warnings that FB is not called, you can ignore that for time being)
4) in FBD of source program press CTRL+A to sellect the logic and paste it in destination program.
5) From destination program, delete the unwanted logic and variables.