Welcome (back) to the PLCTalk forum community !
What have you already tried, and what exactly isn't working for you ?
The kind of controller you are using, and some specifics on the VACON make and model, and some information about the connection (I'm guessing it's Ethernet) would be very helpful.
Does Vacon provide an Electronic Data Sheet (EDS) for that drive ? Can you post a link to their user manual, especially for the appropriate network interface module ?