12v --> 10v Nowforever D100S2R2B inverter & MKS-V-V02 CDXHCTECH board

[EddyCurrent]

My interpretation of the E100 manual is that - yes - it provides a 12V supply to the speed controller but that the AI1 input still remains expecting a value from 0-10V from 0-100% RPM. That's pretty much backed off with the graph that the OP provided (full RPM at 20000dmd/24000full x 12V(ref) = 10V). Reading the manual the value for the AI1 input is programmable from 0..10V, but not beyond. There is a gain setting that can be applied also, but I'd expect, again, that requires that the AI1 input is limited to 10V. My concern is that the response to the AI1 input will be limited at 10V, and so no amount of scaling applied by the controller in the VFD would counter this.

What you say is correct but;
1. Regardless, the vfd diagram does show the input connected to 12v
2. I never intended that the parameter should go beyond 10v because that is obvioulsy it's limit set in the firmware, my intention was to set it so that whatever was output from Mach3 e.g. S20000 actually produced 20k RPM at the spindle.

[Neale]

What you say is correct but;
1. Regardless, the vfd diagram does show the input connected to 12v

Again, we are interpreting a Chinglish manual (or diagram, in this case) so there is a bit of guesswork here! The given diagram shows a pot supplied with 12V. If the idea is that the pot is uncalibrated and you use it in conjunction with the VFD display, then this is fine - in effect, it just reduces the rotation of the pot spindle to go from zero to full. Ditto, I guess, if the pot has a calibrated scale associated but again you won't use the full pot travel.

Slightly different situation where the analogue input is driven from an external source, although it's a pity that the BOB or whatever doesn't regulate the DC input to ensure that the output range is correct.

[magicniner]

Guys,
With the right pot the source voltage is close to irrelevant so long as you can't blow the VFD input with the output.
Instead of arguing semantics why not posit a functional solution to the problem as it stands.
Offsetting voltage with diodes chops off the bottom of the range BTW ;-)

- Nick

[Doddy]

No it doesn't. Read my post - it's reducing the Vref voltage from 12V to 10V. The controller's charge-pump will then generate a voltage proportional to the M-S ratio of the demand vs Vref - from 0v to 10v.

It is a functional solution.

I didn't think the OP had a "pot" - if he did, then the solution would be to introduce a positive-side static resistance, e.g. 2k on top of a 10k pot, which would give a sufficient offset from the 12V reference voltage. But that's not the design case here.

Re. the chop-off. Nope, what you have interpreted is the insertion of the diode chain into the Ain1 input, that's not what I posted.

[magicniner]

So the BOB will function properly with 10V input rather than 12V?

Bonus, you've fixed it!

Nice one!

[Doddy]

The BoB requires a 10V ref input. The implementation is flawed by driving that with a 12V reference.

[magicniner]

I know it would be a bit more faff but if it really needs 10V in from a 12V supply I'd put a regulator in ;-)