N0VUSUN and Mitsubishi-D700-SC

[Doddy]

Dave, sorry, I'm morbidly curious as to your choice of wiring the CAT-x UTP cable with each pair connected together. There's nothing much wrong with this and it probably presents a clean and cheap 4-core cable and bi-wiring each pair like this will reduce the resistance of the wire. But you used the term twisted-pair, and that has a particular connotation with respect to EMI - I guess you're aware that the way that you've wired that is not exploiting the twisted-pair?

Anyway, that's casual banter. If I'm going to reply I'll try to add some value. 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.

[Daveo]

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.

[Doddy]

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.

[JAZZCNC]

I'll shut-up now, Jazz is giving clear instruction and it helps no-one for me to talk over the top of another.

No don't Doddy you have actual experience with this controller and more experience than me with electronics so your the perfect man to help him. Crack on and I'll just dip in if I see something that gets missed.

Edit: Perfect example I also missed the pulling up not down in the VFD manual which proves "you-the-man" . .

[Daveo]

Nvem S-Axis out1 Orange and White twisted pr goes to STF on the VFD..... through relay
Nvem S-Axis out2 Green and White twisted pr goes to STR on the VFD.......through relay
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.

So do i keep the above connections but with the addition of a relay,
i have these relays that came with a box of parts i ordered.

[Doddy]

From the manual...



The outputs are opto-coupled, max 50mA. But that "max" is the maximum capability of the opto's transistor, not a guarantee of switching current (this might, probably will, be less).

I've googled the coil resistance of the MY4N-J and not getting anything sensible, similar OMRON power relays, 24V are around 650R so we can guess a switching current for reliable operation around 50mA. Whether you get that out of the NVEM will need you to experiment but I wouldn't bet the house on it working. If not, you'll need a current amplifier (a simple NPN transistor would do).

And you'd need to protect against the back-EMF from the relay, regardless.

If that makes sense then I won't bother with a diagram, but if a diag would help then let me know.

Mike

[JAZZCNC]

I use these Omron MY4N-J and they typically pull about 36ma. Dave if you have a meter that can read current then test on the bench to be safe.