On 02/28/2011 08:56 AM, Moses McKnight wrote: >> Looking again at the Sercos3 implementation, each "host" requires at >> least a two-port network interace. That's how they implement either the >> "Line", "Ring" or other network topology. Each "host" has to process >> the data and then pass it on to the next host in a host 2+n topology. >> >> The "Ring" topology looks to be the most efficient, since two channels >> are being used to move the data around the circuit, and the second >> channel offers a bit of redundancy of the primary channel goes down. >> >> For environments that have multiple machines, this could be an issue >> with multiple, long network cables going from the master controller to >> the slave boxes. With that in mind though, it's kind of hard to imagine >> multiple instances of EMC2 running on one controller PC controlling >> different machines. For a single control PC sending data to a single >> control box, this shouldn't really be an issue. >> >> Interesting also how the protocol utilizes multiple length packets (or >> as they call them, Telegrams), anywhere from 84 bytes to 1538 bytes in >> length. >> >> Mark > > Sounds like standard ethernet frames. I would imagine they would use > standard frames because ethernet hardware is expecting that. > > http://en.wikipedia.org/wiki/Ethernet_frame > > Moses
Almost, except that standard Ethernet frames are typically of non-variable length, adjustable only by changing the MTU, and are "padded" to maintain the frame length being used. The Sercos3 seemingly allows variable length frames. Mark ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users