Karl Reichert wrote: >> Karl Reichert wrote: >>>> Jan Kiszka wrote: >>>>> Karl Reichert wrote: >>>>>> Jan Kiszka wrote: >>>>>>> Karl Reichert wrote: >>>>>>>> Hello, >>>>>>>> >>>>>>>> I have a question concerning RTcfg-frames. I couldn't completely >>>>>> understand from RTcfg.spec how these frames are looking like. I made >>>> two models >>>>>> and I think one of these is correct (see attachment). Which one? >>>>>>> The first one. RTmac frames have their own Ethertype (0x9021), and >>>> they >>>>>>> only contain discipline frames (like TDMA) or encapsulated non-RT >>>> frames >>>>>>> (see the vnic tunnels). RTcfg frames are just plain RT payload, like >>>>>>> frames issued by RT-applications. >>>>>> BTW, Ethereal, err..., Wireshark perfectly understands RTnet. =8) >>>>>> >>>>>> Jan >>>>>> >>>>> Thanks. Another question: Are those Frame Identifier Bits (B4..0) the >>>> same like the ID? It's little bit mistakable because they are 1 Byte >> (all >>>> taken from RTcfg.spec). >>>>> If not, what if the Frame Identifier for / filled with? >>>> I see the confusion: "Frame Identifier" may rather be called "Frame >>>> Type" so that "Frame Version" + "Frame Type" form the "Frame ID" (or >>>> just ID) as this byte is called later on. May may grab this information >>>> >from the textual description, but the naming can indeed be misleading. >>>> >>>> HTH, >>>> Jan >>>> >>>> >>>> PS: _Always_ reply to all... >>>> >>> Another question, maybe very simple but can't find it in the spec: How >> is data send? Just as a plain/raw packet or is there also sth added like >> version or type in the TDMA-Frame? >> >> But that should be clear from the spec: plain Ethernet frames, no >> additional headers. >> >> Jan >> > Thanks Jan. I also have a question to the normal starup, Calibration Phase: > The Slaves are waiting until Slot Timeout before they send their Calibration > Request. Is this timeout a random value? Because there aren't any sync clocks > yet, I think this value cannot be a value to help them to send their answer > in their timeslot, right?!
There are sync frames at that point, the master is already fully functional. The slaves just have to know the parameters of at least one slot that they can then use for the calibration. And that data is published via RTcfg. The only systematic shortcoming is that the master-slave round-trip cannot be included into the slave's clock adjustment at that point (as it's yet unknown), so the actual slot transmission time will be slightly later than during regular operation. But given the small calibration frame sizes and a typically larger slot to stuff them in, this practically doesn't matter. Jan
signature.asc
Description: OpenPGP digital signature
------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/
_______________________________________________ RTnet-users mailing list RTnet-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/rtnet-users
