No collisions on full duplex ethernet (which is practically ALL 100bT and faster networks.) You can sit behind another packet from a switch going to the same destination. VLAN/priority tagging can be used to bump real time up to highest priority (jump to the head of the queue put simply.) Takes a managed switch.
On Sun, Mar 15, 2015 at 3:20 PM, Peter C. Wallace <[email protected]> wrote: > On Sun, 15 Mar 2015, Karlsson & Wang wrote: > > Date: Sun, 15 Mar 2015 20:03:56 +0100 >> From: Karlsson & Wang <[email protected]> >> Reply-To: "Enhanced Machine Controller (EMC)" >> <[email protected]> >> To: "Enhanced Machine Controller (EMC)" <[email protected]> >> Subject: Re: [Emc-users] Ethernet! >> >> You are right, there are more bandwidth but there may be collisions. I do >> not now about the switches but for old HUBs the full bandwidth can't be >> used because of collision and there actually is a statistical upper limit >> below maximum capacity. Worst case delay is of course higher. >> > > There are no collisions in a real time Ethernet system, for example RT-Net > uses TDM so each device gets its own time slot. Ethercat allows a higher > update rate for situations where many devices have small amounts of data > since it eliminates the inter-packet delays but GigE has higher useable > bandwidth if the amount of data is larger. > > > > >> For ethercat full bandwidth can be utilized without collisions even if >> there are several devices. I have chosen ethernet because I think it will >> be good enough, it is available in almost all computers and there are cheap >> development boards available with 100Mbit ethernet. >> >> I think Ethercat make a lot of sensors for manufacturers since there are >> no collisions or statistics involved so they could prove the system work >> correct but for a machine built to be used by yourself this proof is rather >> useless. >> >> >> Nicklas Karlsson >> >> >> >> On Sun, 15 Mar 2015 10:58:38 -0700 (PDT) >> "Peter C. Wallace" <[email protected]> wrote: >> >> On Sun, 15 Mar 2015, Karlsson & Wang wrote: >>> >>> Date: Sun, 15 Mar 2015 18:34:13 +0100 >>>> From: Karlsson & Wang <[email protected]> >>>> Reply-To: "Enhanced Machine Controller (EMC)" >>>> <[email protected]> >>>> To: Klemen Dovrtel <[email protected]>, >>>> "Enhanced Machine Controller (EMC)" <[email protected]. >>>> net> >>>> Subject: Re: [Emc-users] Ethernet! >>>> >>>> I have tried Ethernet and it works but if you connect to a switch, hub >>>> or >>>> similar with more devices there may of couse be real time problems. >>>> Ethernet >>>> is cheap and readily avaiable although Ethercat I expect to be better >>>> if the >>>> extra bandwidth is needed. >>>> >>>> Nicklas Karlsson >>>> >>> >>> >>> Actually regular Ethernet GigE is better for bandwidth than Ethercat >>> (AFAIK EtherCAT is limited to 100 mbit by current hardware) >>> >>> >>>> >>>> >>>> On Sat, 14 Mar 2015 18:09:24 +0000 (UTC) >>>> Klemen Dovrtel <[email protected]> wrote: >>>> >>>> I am also interested in rt ethernet. Can you please point out which >>>>> instruction are these, >>>>> RegardsKlemen >>>>> >>>>> >>>>> On Friday, March 13, 2015 3:54 PM, sam sokolik < >>>>> [email protected]> wrote: >>>>> >>>>> >>>>> I still cannot believe that it is possible. I have been testing 2.7+ >>>>> uspace for a while now. It defiantly opens up options. >>>>> >>>>> Building the latest rt-preemt using peters instructions and .config >>>>> made >>>>> the latency on this laptop much much better. I am running a 2khz servo >>>>> thread for a day now. >>>>> >>>>> http://electronicsam.com/images/KandT/testing/0313150923b.jpg >>>>> >>>>> Realtime communication over Ethernet is just darn awesome! >>>>> >>>>> I would not use a laptop for normal machine running - but for >>>>> developing >>>>> systems - it sure will be nice. >>>>> >>>>> Thanks Peter, Micges, Jeff and everyone else that has made this a >>>>> reality. >>>>> >>>>> sam >>>>> >>>>> ------------------------------------------------------------ >>>>> ------------------ >>>>> Dive into the World of Parallel Programming The Go Parallel Website, >>>>> sponsored >>>>> by Intel and developed in partnership with Slashdot Media, is your hub >>>>> for all >>>>> things parallel software development, from weekly thought leadership >>>>> blogs to >>>>> news, videos, case studies, tutorials and more. Take a look and join >>>>> the >>>>> conversation now. http://goparallel.sourceforge.net/ >>>>> _______________________________________________ >>>>> Emc-users mailing list >>>>> [email protected] >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>>> >>>>> >>>>> >>>>> ------------------------------------------------------------ >>>>> ------------------ >>>>> Dive into the World of Parallel Programming The Go Parallel Website, >>>>> sponsored >>>>> by Intel and developed in partnership with Slashdot Media, is your hub >>>>> for all >>>>> things parallel software development, from weekly thought leadership >>>>> blogs to >>>>> news, videos, case studies, tutorials and more. Take a look and join >>>>> the >>>>> conversation now. http://goparallel.sourceforge.net/ >>>>> _______________________________________________ >>>>> Emc-users mailing list >>>>> [email protected] >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>>> >>>> >>>> ------------------------------------------------------------ >>>> ------------------ >>>> Dive into the World of Parallel Programming The Go Parallel Website, >>>> sponsored >>>> by Intel and developed in partnership with Slashdot Media, is your hub >>>> for all >>>> things parallel software development, from weekly thought leadership >>>> blogs to >>>> news, videos, case studies, tutorials and more. Take a look and join the >>>> conversation now. http://goparallel.sourceforge.net/ >>>> _______________________________________________ >>>> Emc-users mailing list >>>> [email protected] >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>>> >>> Peter Wallace >>> Mesa Electronics >>> >>> (\__/) >>> (='.'=) This is Bunny. Copy and paste bunny into your >>> (")_(") signature to help him gain world domination. >>> >> >> ------------------------------------------------------------ >> ------------------ >> Dive into the World of Parallel Programming The Go Parallel Website, >> sponsored >> by Intel and developed in partnership with Slashdot Media, is your hub >> for all >> things parallel software development, from weekly thought leadership >> blogs to >> news, videos, case studies, tutorials and more. Take a look and join the >> conversation now. http://goparallel.sourceforge.net/ >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. > > > ------------------------------------------------------------------------------ > Dive into the World of Parallel Programming The Go Parallel Website, > sponsored > by Intel and developed in partnership with Slashdot Media, is your hub for > all > things parallel software development, from weekly thought leadership blogs > to > news, videos, case studies, tutorials and more. Take a look and join the > conversation now. http://goparallel.sourceforge.net/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
