On Tuesday, March 1, 2022 5:29:51 AM EST Rainer Stelzer wrote: > Hi Gene, > > > So once you've bought the controller, there is no other restriction. > > And I assume that royalty is 2x per axis, once for each end of the > > cable. > No, they don't charge twice. > Part of marketing a Fieldbus-System is to make it widely accepted in > the industry, so Beckhoff > (and others like Siemens with Profinet) has/have to find a balance > between protection and easy/low cost accessibility. > > From my understanding Beckhoff is very open regarding the master (who > even does not need a special hardware, > when driven by an RTOS) and are very restrictive when it comes to the > slave (where a ASIC / FPGA is needed in any case) > > Makes also sense from commercial point of view, because in a typical > system there are much more slaves needed that masters. > > > Or can one receiver handle more than 1 axis with acceptable latency? > > A slave in EtherCat's daisy chain topology has an input and an output > Interface. (the biggest difference to most other ethernet based > fieldbusses) > > The incoming stream is shifted out with 1 bit delay to the output. > > At 100Mbit/s -> 10ns delay added up to each slave in the chain. > > The difference between one slave 3axis servo pack and three single axis > servo amps is ~20ns. > But to synchronise the output, all slaves have to wait for the full > frame received. > > Even on a 10 axis system this does not even come close to the total > frame time. > Not to mention the jitter caused by a (soft)RTOS > Which is usually much higher than that. 20ns doesn't even register on my rpi4 with its 12 u-secs of jitter. And that runs my 11x54 Sheldon like Casper the ghost with its new 3 phase stepper/servo's. Its eirie watching it move dead silently at normal cutting speeds.
> cheers > > Rainer Thanks Rainer. Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
