roland Tollenaar wrote: > Hi > >> A full-text search over 2.6.21 didn't show me which source file is >> involved here. :-/ > > Sorry, memory failed me here (did not have the other box present). I > just dug out the other PC and checked. Its called natsemi. Also > checked the rtnet/modules directory but I don;t see anything similar > in it.
But you are lucky: it's there, just waiting to be enabled during RTnet configuration. > >> >> Rarely impossible, only few hardware is so weird that you cannot >> >> convince it to send/receive deterministically given a non-chaotic >> >> network (like RTmac/TDMA, Ethercat, or other RT protocols ensure). >> > Sounds difficult if one has little experience with this. I am just >> > starting to read your paper "RTnet-A flexible Hard Real-Time Networking >> > Framework" so you can imagine that I am probably not quite up to the >> task. >> > > >> You should be able to test a look for your specific scenario. I wonder >> if EML against the rtlo device wouldn't be much like an empty Ethercat >> bus. So you should be able to test the elementary cycle - though without >> process data transfer... > Ok. > >> >> Ethercat forms a ring: The master sends out a frame that is handled >> on-the-fly by the slaves as it passes through them. That frame arrives >> back at the RX line of the master's NIC and is thus received just like a >> frame sent by some peer node in a normal Ethernet. > This was new to me, great to learn. But rtnet (forgetting EML) also > looks for slaves when set up as master. What response is it waiting > for? Is that an ARP broadcast to specific addresses to which it is > awaiting a reply? If RTnet is using its full stack, there is (besides TDMA medium access control) RTcfg traffic on the wire, kind of ARP. But those protocols will not work over rt_loopback. Jan
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