Regarding spindlespeed

[Socke]

How fast are the inputs, regarding spindlespeed (axbb-e)? I have an encoder, which consists of a disk with 100 holes for the encoder and 1 hole for the index. And 3 light barriers. Sadly the inputs need at least 10v, so I have an additional optocoupler, to bring the 5v up to 24v. The signal from the light barriers is very clean and even, even up to 4800 u/min, which should be 4800/60*100=8kHz. If you count on and off separate, it’s doubled. With the optocoupler, the signal gets unsymmetrical, but at 3500 u/min it works, and at 3800 u/min it doesn’t, although on my oscilloscope there’s almost no difference.

The other question is: how can I limit the top speed of the spindle? I have 6 pulley-settings, and on the highest one I’d like to limit the top-speed, as the spindle starts emitting vibrations.

[Socke]

I added some pics from the oscilloscope. 500 and ~4700 rpm at 5v and the same for 24v, where ~4700 at 24v is inverted due to a different optocoupler, as the old one didn‘t go beyond 3000 rpm.

Another idea would be skipping the optocouplers on the UCSB and use the 5v signal directly. Is that possible? The 5v source is the same as for the axbb-e.

[cncdrive]

Hi,

The max. encoder count frequency the motion controller can read is 50kHz.
5Volts works with the inputs, we just safely specified it to 10V in the users manual, but all optocouplers on all motion controllers are tested with both 5V and 24V before shipping and by design 5V is on the edge.
So, you could use 5Volts for the inputs if really nessessary, but 10V+ is adviced, because the higher the voltage the more noise immune the signal will get.

If the spindle is controlled with analog signal or PWM by the UCCNC then you can set the max. PWM and max. RPM in the spindle settings to limit the spindle speed.

[Socke]

Thank you, I'll give that a try.

[Socke]

I‘d suggest, you put that 5v hint into the manual. Would have saved me weeks of fiddling around with optocouplers, because it works perfect!

Regarding the max. Rpm, I only see it near the pulley setting. Is that the right one?

Another point regarding the spindle-speed: now the encoder is working, I see the rpm preset doesn’t fit the actual speed. It’s about 200 of at the lowest (100 set, 300 actually at around 2Hz! With the highest pulley), and it gets lee the higher the speed and fits perfect on topspeed (4800 set and actual at 100Hz).

Now how can I improve that? PID-settings, Modbus control the vfd or a better pulley-setup? Or something else?