Faster controller for high count servos?.

[Dazp1976]

This may not be the right place to post but:
Are there any plans for a new ethernet controller fast enough for servos with high count encoders 17bit etc.

Recent breakout boards have optocouplers etc that can go to 10mbit, however. The likes of the UC300eth limit you to a maximum of 400khz.
The 300 is a great controller and something based on this but faster would be good.
Maybe add 2 more input based ports or some dedicated encoder ports to it.

As far as I know, the ESS can go faster than 400khz but I'm not an avid fan of Mach.

[cncdrive]

We see a problem with pulsing that high frequency. The issue is that the higher the frequency is the higher speed the drive's optocoupler has to be and so the less filtering is possible and so the more noise sensitive the system becomes.
We don't think that it is a good idea to do MHz stepping frequencies.
For example the Leadshine ELP servo drives have 17bits encoders which is more than 131000 encoder counts per rotation and the motors can rotate upto 3000 RPM this means more than 6.5MHz frequency.
The good thing is that these drives ofcourse have an electric gearing with which you can set the encoder resolution to anything you want below 17 bits.
The motor is still using the whole 17bits for the motor commutation and for the PID loop and so the motor is still running very smooth even if the encoder resolution is tuned down.

So, we think that doing that high stepping frequency is not a good idea, we think that "bus based" system is the key, EtherCAT and CAN bus and Fieldbus is mostly used.
EtherCAT can do very fast communication, so it is suitable for using high resolution motors/encoders.
We already working on developing an EtherCAT motion controller. We have some LEadshine ethercat stepper and servo drives using for the development.
Please don't ask, because I cannot tell you when this development will be finished because currently we working on many other projects too, e.g. we developing the lathe support for the UCCNC.

[Dazp1976]

Just wondered if you were thinking about it and seeing which way you were considering going with it.

I'm a long way off from thinking about even playing with RS485 communication atm.

[cncdrive]

No, not RS485, but etherCAT.
EtherCAT can do extremely high speed communication, it can read and output ethernet packets in sub microseconds.
Since motion control works with a speed loop internally, basically we only have to replace the step/dir interface with an EtherCAT stack.
So, the motion controller can update the speed of the motor not with using step/dir signals, but with EtherCAT packets.
This makes communication more stable, no more lost steps, because etherCAT has very good packets error handling.
And another good thing about etherCAT is that the master device (the motion controller) can be a standard ethernet port, only the slave (drive) has to have a special EtherCAT slave IC.