Sercos 3 was one example of the use of ethernet for real time control. Another example is ethernet i/p. Again it uses standard ethernet technology and allows the use of switches between the host and slave. It all comes down to timing. AB claims they do +/- 100 uS without modified hardware. With IEEE 1588 compliant hardware they can get it down much lower. It all comes down to the application and what is required.
Refer to ODVA's CIP Motion and CIP Sync for more information. I use AB PLC's and Bosch Rexroth drives using ethernet I/P communication on a daily basis without 1588 hardware and have found it to offer exceptional performance. My comments were relating to someone indicating that ethernet could not be used in a real-time application. Thanks Jp Sent on the TELUS Mobility network with BlackBerry -----Original Message----- From: Mark Wendt <mark.we...@nrl.navy.mil> Date: Mon, 28 Feb 2011 08:37:19 To: Enhanced Machine Controller (EMC)<emc-users@lists.sourceforge.net> Reply-To: mark.we...@nrl.navy.mil, "Enhanced Machine Controller \(EMC\)" <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Guidance on usb comp On 02/28/2011 08:19 AM, Dave wrote: > Siemens DriveCliq works the same way. Everything is point to point. > No external hubs or switches. > I think the controller I was using recently had 6 or 8 Ethernet jacks. > The drive module had 3, one for the connection to the controller and two > for encoder connections. > I think the line module (Ac to DC smart power supply) had 3 Ethernet > jacks. Hooking everything up was very quick. > > Dave 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 ------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------ 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