feedrate override using rotary momentary switch?

[routercnc]

Can anyone help with the following question. You'll notice on my new panel design the digital readout below the spindle on/off switch and the idea of this is to show the spindle rpm.

This is a voltmeter and I intend to connect it to the V0 and ACM pins on the VFD. See bottom right hand corner.


I haven't connected it yet but suspect that at maximum 24,000rpm it will read 10V and 0rpm will be 0V. I've looked into this but not found anything yet to confirm. Probably because the rpm is shown on the VFD and most people look at that but mine will be covered in the new enclosure.

I'd like to make it show 24V = 24,000rpm if possible. Can this be done? I looked at DC/DC convertors but I think they give a fixed output rather than a tracking one. Any other way?

If not then I think I can go the other way and make it read 2.4V = 24,000 rpm by using a pair of resistors in series, sized to drop the 10V to 2.4V across the top resistor, and reading across the lower one to ground. Should this work?

I'm not looked for complete accuracy but nearest 1000rpm would be fine. Any ideas?