On Wed, 17 Jan 2018 19:56:21 -0500 Gene Heskett <ghesk...@shentel.net> wrote:
> On Wednesday 17 January 2018 17:20:47 Nicklas Karlsson wrote: > > > On Wed, 17 Jan 2018 16:41:59 -0500 > > > > Gene Heskett <ghesk...@shentel.net> wrote: > > > On Wednesday 17 January 2018 11:10:53 Nicklas Karlsson wrote: > > > > On Wed, 17 Jan 2018 09:27:25 -0500 > > > > > > > > Dave Cole <linuxcncro...@gmail.com> wrote: > > > > > The text below is at the end of the SOEM page from the link > > > > > below. https://openethercatsociety.github.io/doc/soem/index.html > > > > > > > > > > So how does this work?? The SOEM software itself is GPL, but > > > > > if you implement an Ethercat master, you need to get a license > > > > > ?? > > > > > > > > Why a license? > > > > > > > > I have nothing about sharing my work but copyright issues i > > > > something different. > > > > > > > > Then in european union I read something about interoperability so > > > > you are always allowed to make your own device to talk to other > > > > device. > > > > > > > > > That's an interesting approach. > > > > > > > > > > If the SOEM code is all GPL, then how could adding GPL code to > > > > > GPL code result in something other than GPL code ? > > > > > > > > > > From a practical standpoint, I think we need to figure out how > > > > > to get networked drives connected to LinuxCNC if we want > > > > > LinuxCNC to live on. At some point analog servo drive interfaces > > > > > will become like 5 1/4" floppy drives... They were once > > > > > common. > > > > > > > > Yes. > > > > > > > > Michael Büsch already implemented a profibus master. I have it > > > > running against an IO module and millions of these kind of devices > > > > have been sold. I think he implemented on Rasberry and I had some > > > > timing issue before running on ordinary computer but have not > > > > looked further because I have been busy with something really good > > > > for servos and looking for a new woman. > > > > > > > > Bandwidth required to replace an analog signal may be surprisingly > > > > high and for a control loop even though there are plenty of > > > > bandwidth it need to split in many small messages. Ethercat solve > > > > this problem in a similar way as cascade coupled shift registers. > > > > > > > > > > > > Nicklas Karlsson > > > > > > I think this might be right up PCW's alley. He is already selling > > > some cards that expand via an rj45 jack. Perhaps he could chime in > > > here as to the advantages and disadvantages of adapting the firmware > > > to be something like this, but call it something other than > > > ethercat. > > > > > > Changing the subject a bit while I ramble, we have some amazingly > > > cheap rs485 devices about, costing less than a buck each in bags > > > from ebay. > > > > Yes rs485 is a cheap and a very good driver. UART however have limited > > speed and not the least clock accuracy problem at higher speed. With a > > device with as many UART ports as needed this might be a very good > > solution, speed could also be adapted to cable length then long cables > > are needed. > > > Then one good uart, something that can run in the multimegahertz speeds, > later 16550's can, and some and gates to send or receive from that rs485 > channel might be a lowercost item. ... One the new Micro controllers usually with a Cortex-M*- CPU is a cheap item available from below $1 per piece and upwards. They usually have both UARTs and SPI(s) but no really good bus could be built by them. Ethercat is a good bus and a LAN9252 from around $8 will connect them. Nicklas Karlsson ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
