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Author Topic: Alternative to Step-Dir.  (Read 1422 times)

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Alternative to Step-Dir.
« on: June 04, 2017, 06:32:53 PM »
Does Mach3 or 4 for that matter have any other motion control alternative to step-dir? I have used both Steppers and Servos but the both types of drives just use step-dir.  So, any other way like SPI or something like that?

please excuse my ignorance but it never hurts to ask.  I am implementing a new driver that is still in development and their Step-Dir communication as not yet been implemented.

Re: Alternative to Step-Dir.
« Reply #1 on: June 04, 2017, 06:48:53 PM »
Yes they make analog motion controllers that work with Mach. Look it cslabs for an example.
Re: Alternative to Step-Dir.
« Reply #2 on: June 04, 2017, 06:56:30 PM »
Something Like this would let me talk to the drive with CAN? My drive does support can.


Re: Alternative to Step-Dir.
« Reply #3 on: June 04, 2017, 07:21:39 PM »
a goodly fraction of modern servos drives have some sort of field bus control. There are a bewildering array of communication
protocols in use with each manufacturer claiming theirs is the best.

One of the most advanced and capable is Profinet. I believe it was started by Siemens and is certainly dominated by Siemens.
It has been licenced to other manufacturers who have added some great components and facilities. I think Siemens is guilty
however of setting the licence bar to high and so Profinet is really expensive.

Another very capable protocol is EtherCat. The licencing setup is such that many top flight servo manufacturers have adopted it.
The basic idea is that the central controller, be it a PLC or PC, sends numerical data over Ethernet to all the servos of a machine
or factory installation. On a 'Go' signal all servos move so as to arrive at the correct destination at exactly the right time. The servos
achieve co-ordinated movement but each is in fact controlled by its own drive. Its called 'distributed motion control'. Its fascinating
and right out there!

I have a customer at work who has a really big Plasma table...$100,000 plus. It uses Panasonic servos and Logosol drivers using
Panasonics proprietary comm protocol using RS485. It effects distributed motion control in a manner similar to EtherCat. There is
enuf info published for me to seize control of the Logosol drives but would require me to write a plugin for Mach4, quite an undertaking.

As it stands Mach4 develops position-velocity over time trajectory and communicates that to a motion controller that generates the
pluses (step-dir or CW-CCW or quadrature) for the drives. If Mach4 had an EtherCat plugin the servo drives could be daisy-chained
together with Ethernet cables and the drives are smart enuf to take it from there.

Over the coming years distributed motion control is going to be ever more important. I would dearly luv to write an EtherCat plugin.
It is beyond my programming skills at the moment but I believe that someone will take up the challenge and maybe it could be done

Recommend a Google search for EtherCat....its a fascinating read.

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