Hello hugo.
Sorry for the confusion, it was a long day yesterday - yes the BIN_TO_DWORD does work perfectly. I tried creating a new project and used the OSCAT library file directly. It all works perfectly
Unfortunately in my Twincat project, I have used some Twincat library files that have the same function block names as the Oscat library so I can't just add the Oscat library or I get errors, I have to export the function I require and import save them as a separate library file.
For some reason this library file did not save correctly hence the error.
Have re-imported this function and is working perfectly.
Thank you for your help and hard work Oscat is a great resource and very appreciated.
Matt