Delta ASDA-A2 servo drive via ModbusRTU

STEPGEN_MAXVEL should be in RPS Rev per Sec. So just divide your setting by 60.

Instead of 12500 change it to 208,3333

0x2102 wrote:

You can keep the A2 set to PT mode and configure the StegGen in LinuxCNC for velocity mode.

 

How is that supposed to work? I'd like to do exactly this with a Delta B3 drive, but the manual of the A2 and B3 both mention that speed mode only works with 0-10V or via registers, which is probably way to slow for CNC. Pulse input can only be used in position mode.

So how do you combine pulse input with speed mode?

forum.linuxcnc.org/38-general-linuxcnc-q...usrtu?start=0#270743

0x2102 wrote:

forum.linuxcnc.org/38-general-linuxcnc-q...usrtu?start=0#270743

This link points to the post, which I quoted for my reply, so it doesn't help me. Maybe my question wasn't clear:

How can a servo that expects a position input via pulses and has an internal position control loop, work with a signal that doesn't contain position information, but velocity information?

If i'm correct, in speed mode, the position control loop is closed in LinuxCNC by evaluating the encoder feedback. This means that we would have two separate position control loops (inside the servo drive and inside linuxcnc) that are unaware of each other.

What is the theory behind this?

In this particular instance, there is no spindle feedback loop
in LinuxCNC (other than the Z axis gearing for spindle synced motion)

The stepgen that controls the spindle is simply run in velocity
mode and this velocity is directly set by the spindle speed command.

Ok, so this only works in the special case of spindle speed control and can not be used to control the movement of an axis?

This can (and has been) done with step/dir systems with linear encoder feedback.
This works reasonably well as long as the position loop in the drive is fast.
(or there is no position loop in the drive as is the case with most step drives)

But is there any advantage over analog speed control when using a delta B3 servo, except for not needing as many analog outputs?

Probably none, but if the drive can do step/dir position control,
I would think you would normally use that in preference to
analog velocity control.

Ok, but in this thread the topic was PT speed mode, not PT position mode, hence my question.