Frank Tkalcevic wrote: >> Frank Tkalcevic wrote: >>>>> I'm not sure why the sync packets were coming out as well >>>> as the rtcfg >>>>> traffic. Is that correct behaviour? I would have >> thought the sync >>>>> process would only happen after rtcfg set up was complete. >>>> It is correct, RTmac/TDMA is in charge of managing the >> media access >>>> right from the start (that's why RTcfg stage 1 frames have >> to include >>>> all information a slave needs to send its own frames, >> namely the TDMA >>>> cycle offset and phase). >>>> >>>> BTW, Wireshark is capable of decoding RTnet frames, maybe >> helpful for >>>> understanding the procedures. >>> >>> That's confusing me a bit. It looks like rtcfg just >> outputs packets >>> as it pleases and doesn't obey real time rules. Does it >> sit on top of Rtmac? >>> Does it need to stop after all the clients are ready and >> obeying the >>> TDMA protocol, or can it coexist? >> RTcfg is plain payload from RTmac/TDMA POV. Check if RTcfg >> frames sent by the master have a fixed offset (minus jitter) >> from the Sync frame. If not, something is badly configured >> (but that is unlikely if you used the standard setup script). > > Things are working fine. The questions are for my understanding of rtnet. > Sorry for being a pest. > > How is the offset defined? In my stage 1 configuration I have... > > TDMACFG rteth0 slot 0 200;ifconfig vnic0 > > which defines one slot at an offset of 200. Is this used for rtcfg? How > does the slave know at what offset to send rtcfg messages?
RTcfg stage 1 is transferring this executable configuration bit to the slave, the slave runs it and, thus, configures its TDMA to emit frames in slot 0 with an offset of 200 us to the Sync frame. This pattern works fine for Unix RTnet nodes, but it already showed it limitations when adding RTmac/TDMA to old Etherboot (I had to parse that script line, relying on its informal layout). We would actually need to define proper config sub-formats (per RTmac discipline) for RTcfg, at least for stage 1. Jan
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