Vareka, Bill wrote: > In our situation, the Master will be powered up and start running and then > over time the slaves will be powered up. In addition, slaves can be > disconnected for periods of time and then reconnected to the network. This > happens without user intervention and potentially without warning. The new > TDMA v2 structure supports hot plugging of slaves which is what we'd need > but I have a question. How does calibration work in this case? Looking at > the code it appears that the Master performs a calibration routine when he's > first enabled (after waiting to look for other masters) via the tdmacfg
Yes, but only if there is currently another active (backup-)master around. This avoids that a restarting primary master screws up the global time when taking over the network synchronisation again. > command. Suppose there are no slaves online yet. I assume the master just > transitions into run mode and waits for messages. Then after a little while > the slave is powered up. Is any calibration automatically performed or are > slaves run with defaults for calibration? Whether automatic or not, what > happens to other high priority RT master messages if we start a calibration > sequence after we're up and running? > Calibration is performed "at the expense" of the joining slave. Take a look at the TDMA spec: a starting slave donates one of its own time slots in a specific cycle to the master in order to let it reply the slave's calibration request. So, there will be no disturbance of other real-time communication taking place in the same cycles (but in different time slots). Also other messages required for slave hot-plugging, namely RTcfg packets, will not cause delays because they are transmitted at lowest real-time priority level (but always in favour of any potential tunnelled Linux packet). Hope that helped, Jan ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_id=7412&alloc_id=16344&op=click _______________________________________________ RTnet-users mailing list RTnet-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/rtnet-users
