Denford VMC1300 - Rescued

[Clive S]

I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator

Not sure what you mean here, would you mind elaborating please.. I used the pwm signal from my bob and the https://www.ebay.co.uk/itm/111654184682 to convert it to 0-10V isolated for the spindle driver board.

[m_c]

Not sure what you mean here, would you mind elaborating please.. I used the pwm signal from my bob and the https://www.ebay.co.uk/itm/111654184682 to convert it to 0-10V isolated for the spindle driver board.

Does that board isolate the PWM in from the 0-10V output?
I'm not sure if the 0-10V output from the DDCSV/RMHV will be compatible with that board. It would depend on if that board is simply relying on referencing the PWM voltage (should be fine), or measuring the actual PWM.

Actually, I've just checked the spec of a DDCSV, and it states the spindle output can be configured as a PWM, instead of analogue. I can't find any mention of whether it's isolated though.


The problem with SCR type drives, is the far more common non-isolated versions have the control wiring at near mains voltage, so your 0-10V source has to be isolated. Denford did use isolated drives in some machines, so yours may have an isolated drive, or your BOB PWM may be isolated. The only guaranteed way to check without knowing the exact board you've got, is to power the controller up, and then measure the voltage between the speed control terminals and ground (or neutral/0V).

[Clive S]

Does that board isolate the PWM in from the 0-10V output?

This morning I checked the voltage between 0-10V and earth about 200V and between PWM and earth 1.5V so it isolates the two.

[m_c]

This morning I checked the voltage between PWM and earth about 200V and between 0-10v and earth 1.5V so it isolates the two.

Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)

[Clive S]

Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)

Well spotted. I have edited mine would you mind editing to save confusion for others.

[Chas Ixion]

Just a quick update. Got a scope on the 0-10v spindle speed output from the RMHV and its analogue and not PWM.

The manual seems to suggest that it is possible to configure the unit to output PWM but I can not find anything in the manual to show me how.

[GND]

I'm in the process of planning the conversion of my recently acquired Novamill, and came across this during my research - https://www.summet.com/blog/2016/01/...-speed-control. It shows how to tap into the existing spindle drive isolation circuit with your own PWM signal, thus saving any new circuits or power supplies. In my case I'm just replacing the top controller board, and replacing it with a modern motion controller - but keeping the lower board and the stepper drivers - so this should work for me. Sounds like you may be replacing more of the electronics, so it may not be appropriate. But hopefully this is useful info for others reading the thread.

Cheers
Graeme