Thanks Boyan,

You have answered the question whether I can join the digital & analogue earths within the VFD. I tested for continuity between them and they are certainly separate.

I hope to receive the new controller this week, but with the backlog of work I'm not going to have time to play with it, so I'll run it with the old Kress spindle in the meantime. As soon as I get a moment I'll probe the ports and see what I am getting from them. I was thinking that to get the speed control that I could maybe use pins 18 & 19 and connect those to VI & ACM of the VFD, but maybe that's mixing grounds between different machines again. If I'm stuck, to switch the spindle on & off, I can use the 240V spindle output to power a relay to operate contact between FOR & DCM and I have a 10k pot to operate the speed.

I'll update this as soon as I get any further.

Thank you,

Gavin