Marc Bodmer wrote: > Recently I stumbled upon Ethernet Powerlink. They claim to offer > a true open Realtime Ethernet protocol under the BSD license. > Cycle times down to 500us with standard Ethernet Slaves and down > to 100us with special hardware. > > I'm not sure what "cycle time"means, but that certainly is not a great figure. Maybe, though, it is about where other Ethernet hardware runs, I really don't know. If you wanted to do a several KHz servo cycle, it just can't hack it. > So far there does not seem to be any very low cost hardware available > with Powerlink interface yet, But at least there is hardware available > like digital/analog IO, drives and so on. This is a great plus compared > to eg. RTNet. (There do not seem to be any products supporting RTNet, > unfortunately). > > I don't know if this is compatible with our rtai version of Linux. Can you tell if it is?
I am working on getting the Beagle Board (with TI's OMAP3530 processor) set up with a real time kernel, but that hasn't happened yet. I have bought another Beagle Board and accessories to ship to Torsten Koschorrek (the RTAI maintainer for ARM-based ports). I am also working on trying to find out why GPIO pins on the Beagle Board can't be toggled any faster than 250 ns, although the CPU is 150 times faster than that. The Beagle people don't know, so I am now throwing this in TI's lap. This is not a killer problem, but it definitely is a limitation. If you have to do a couple different steps in software to handshake each byte across, it could be as bad as half the speed of a good PC parallel port. Since all the hardware is INSIDE one chip, it ought to be able to flip GPIO pins something like 10 times faster. EMC2 has a mode of operation where the GUI is run on another computer over Ethernet. The Beagle Board is a 500 -600 MHz computer, with none of the insane legacy architectural garbage that encrusts the X86 PC. It should be a lot closer to the ideal embedded system, perfect as a platform for EMC. (It is a tad expensive, about $200 to get a fully functioning system with SD card and Ethernet adaptor.) Anyway, work in progress, but if this speed issue can be solved, and if Torsten can bring up a port of RTAI on it, I think we can have a nice EMC2 platform that fits in the palm of your hand! This speed issue won't be much of a concern for software-generated steps, either. Jon ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
