Hi Irving, Ecat,

I just saw the picture in the manual (same as your link ecat), plugged a standard network cable into the RJ45 socket on the VFD and removed my internet cable from my PC and plugged the other end in there. When it didn't work I just left it as it's not vital. However, looking back at the manual it does go on to explain a bit more, so its a case of RTFM !

Will look into an RS485 interface card and decide whether to bother for now, but thanks for your help.