This Ethernet issue has come and gone in the past and the reason EMC2 doesn't use it, so far, is that it hasn't brought enough to the table to justify the effort to make it happen. The current options for realtime control on EMC2 are the parallel port and FPGA cards on the PCI bus. The reason these have survived is that they present the shortest hardware and software distance between a real time command and the hardware that makes the command a reality, and also the shortest distance between synchronous elements. Ideally, I think one would want the control hardware connected directly to the I/O or memory pins on the processor.
On the other hand, to keep cost down, we need to deal with cheap consumer hardware which is turning more towards plug and play, mobility, entertainment and communications, which mostly doesn't apply to CNC control. That is why I think using a laptop, which might be great for watching movies on an airplane, and LAN technology for complex and dynamic networks, is not appropriate for controlling one machine that may only be moved twice in its life time. There is just too much fluff between the processor and the CNC hardware. The only way to offset the fluff is to increase the speed. The way to increase speed is to increase complexity, which needs to be offset by more speed ... (BTW, SPI is low fluff and speedy) Frankly, I think the desktop PC / parallel port / PCI/FPGA solutions we have now are the best balance of cost and speed, and will be for at least the next five years. I do see a long term trend where desktop PC's will go away and we will need to find a different platform. I think the hardware will still be available, but will move to the specialty market and become expensive. I predict that the media and communications trend for consumer products will close that area for the next platform. With the increase in home and automotive automation, an appliance or engine controller might be the next platform, but these won't be open. The recent success with Arduino (RepRap?) may suggest that the next CNC platform may be a ground up, grass roots redesign -- open hardware for the existing open software. I plan on trying to direct my effort there. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
