I have been following EMC2 for years, but have only recently been able to actually start using it. I am particularly interested in this renewed attention to using Ethernet for control communications.
We have some inverted pendulum systems for our Feedback & Control class that students control with state-space algorithms, and I use plain TCP/IP for the interface between the PC running the control loop (in Matlab or Octave) and the physical system. I use a Wiznet hardware TCP/IP module (http://wiznet.co.kr) and a Spartan3 FPGA with a Xilinx PicoBlaze softcore processor to provide the slave end communications. With a Dell GX620 and Ubuntu 10.04 running Octave, I can do 1000Hz loop rates transferring sixteen byte packets (plus TCP overhead) each direction. In my application I use the FPGA to provide the timing, but there is no reason that RTAI couldn't do that instead. The Wiznet module makes plain TCP or UDP communication absolutely trivial to implement, as the entire stack is contained in silicon. It is also blazingly fast for the same reason. The module costs ~$20, and the chip price is ~$7. I have built some boards with the FPGA and wiznet chip together, but haven't finished testing those. So far I've been using Digilent Spartan3 boards. So if EtherCAT looks to messy, you might consider something simpler like plain TCP or UDP. -- Ralph Ralph Stirling Project Engineer Walla Walla University School of Engineering 100 SW 4th St College Place, WA 99324 [email protected] http://engr.wallawalla.edu/engr480 ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
