Quote Originally Posted by Daveo View Post
OK, thanks for the advice
so below is where i stand on the wiring and that makes sence...

Nvem S-Axis out1 Orange and White twisted pr goes to STF on the VFD
Nvem S-Axis out2 Green and White twisted pr goes to STR on the VFD
The other two twisted pairs blue and white,brown and white have not been connected as yet but looks like terminal 5 and 2 after reading your reply

S-axis /Gnd1 goes to terminal 5 on Vfd which is Analog Gdn
S-axis/VSO goes to terminal 2 on VFD which is 0-10V.

just a bit confused on the last part...

Doddy
Jazz is correct - you're having to short the analogue and digital ground together for the VFD. I did do this on mine, also a NVEM, and it worked, though I did get some fluctuation in final spindle speed that may or may not have been associated with this and a ground loop. I never did find out what because I replaced the analogue speed control with a £2 RS485 serial link to the VFD.
just a bit more info on what i need to do here.

That last bit - and this is with reference to the commonplace Huanyang VFD - the discrete for FOR/REV have a digital ground (short to ground to activate), labelled DCM, and the analogue speed control had an analogue ground, labelled ACM. For the NVEM with a single ground you have to short the ACM and DCM together to get a common ground (or export two grounds from the NVEM to the ACM/DCM ground references on the VFD).

Now, just reading your linked VFD reference it's clear that the control mechanism is very difference to the Huanyang. The STF/STR need to be pulled up (not down, as with the Huanyang) to the internal PC +24V supply. At this stage my suggestion would be to use the NVEM to drive separate relays and use the relay contacts to connect as per the manual. I'll shut-up now, Jazz is giving clear instruction and it helps no-one for me to talk over the top of another.