AC Servo speed / direction / Start/stop?

[FerrumD]

Hi

My 3-Axis CNC has been working nicely (G0704 CNC Conversion)... but the original induction motor is a "tad" annoying with both it's custom control board and difficulties in controlling the speed via UCCNC and general limitations.
Along with a project of replacing the enitre milling head with a new BT30 spindle with ATC capabilities I've also acquired a 1kW 3000rpm AC Servo motor & controller (the T6 from stepper online).
The motor is actually quite impressive for it's size.

What I'm currently trying to figure out is HOW I can connect it to the UCCNC system... (I've got the UCCNC ETH400 and UCSB) ...
I want to be able to:
- Start / Stop the spindle
- Set RPM
- Set rotational direction...

AND in a future moment in time, use the spindle's encoder to realise
- accurate positioning of the spindle for a 10-12 piece rotary ATC which requires Spindle-Orientation so that the two anti-slip segments to engage with the slots on the BT30 tool holder...
- tapping...

I think start / stop is quite easy.
But I can't figure out how to set the RPM.
or how to use the encode feedback

most important for now are: start/stop, speed, direction...

any help is welcome...
thanks.

[FerrumD]

Still looking for some input on this with UCCNC and the ETH400 & UCSB...

[cncdrive]

Well, to set the spindle RPM you need an analog 0-10V signal.
The UC400ETH does not have an analog port (The UC300ETH-5LPT and the AXBB-E have).
Also the UCSB does not have a digital to analog converter.
So, you can use a PWM signal with connecting an UCSB output to 10 or 12Volts using a resistor and then smooth the output with a resistor and capacitor and connect it to the analog input of the VFD.

Or you could use a USB or ethernet RS485 adapter if your VFD supports Modbus and then use the Modbus plugin, but you might need to make some code, my collegue Dezsoe can help you with that.

For Start/stop and CW/CCW rotational direction you can use any outputs on the UCSB.

[FerrumD]

Thanks for the Reply...

Here's the thing , my AC Servo's driver also supports PUL/DIR signals...
And I can actually get the thing to start stop, reverse, and change speed with UCCNC...
Connecting it like I would any stepper motor.

The issue when I do this is, that the Servo runs VERY SLOW... so when I tell it to run at 3000RPM it more likely runs at 80RPM...
Something like this.

Is there anything you can think of - or is PWM the only method... ?

modbus...
Ok - help would be appreciated!! the Driver has support for MODBUS and there's the mentioned port...
I have however ZERO Experience with modbus - so help would be much appreciated.

thanks

[cncdrive]

If it supports step/dir signals then you can configure it as step/dir spindle, but you have to setup the steps per value properly to have the correct velocities.

[FerrumD]

If it supports step/dir signals then you can configure it as step/dir spindle, but you have to setup the steps per value properly to have the correct velocities.

How?
I mean say the drive has 10'000 Pulses per Revolution... the problem is this is probably too much for the UCSB to handle...

So I guess;: Do I need to set the electronic gear ratio? ... OR any other idea?

thanks for the help...

[FerrumD]

OK - I have managed to solve it….


got it hooked up as STEP/DIR spindle…
and needed to go and use the „electronic gearbox“ setting on the drive‘s setup to get things to go as I want.

now I can set any RPM I want and it‘s pretty accurate….



What remains to be done:
ENCODER readout…


here‘s the question: would the entire thing be easier through MODBUS?

[dezsoe]

If you have index output from the spindle then you can home it. You can configure e.g. the C axis to use the same step/dir outputs. The only thing you have to take care is not to turn on the spindle and move the C at the same time.