There is also another thing.. if I have RTmac insmoded, but say the TDMA has failed to operate properly in the ./rtnet start. How much of RTmac is still working ? can I still connect to network with stations without RTAI + RTnet and work as expected just without TDMA ?
Not really. The station which failed to start up will not be able to transmit any data as long as you don't issue an "rtifconfig rtethX mac down". The server, although lacking at least one expected station, will work if at least one other client went up.
sorry I am not following you .. what do you mean by "will not be able to transmit any data as long as you don't issue an "rtifconfig rtethX mac
The TDMA plugin simply blocks any outgoing traffic of a station until that node has been accepted by the TDMA master. This blocking can be resolved by shutting down the RTmac/TDMA support of the station.
down" ". But what if the client does not return from prompt after 'rtcfg rteth0 ready', which i manually ^C it out. TDMA is definitely not synchronised properly.. will RTmac still work between the those two statiosn?
When RTcfg comes into play, things currently get a bit more complicated. As you start the RTcfg server with a list of all expected stations, all nodes will wait for this stations at any stage, also at this one (ready). You may add timeouts to the rtcfg commands, but be warned, the timeout support of RTcfg is not fully tested yet. This is because of the current TDMA implementation which generally requires a clean startup of all stations anyhow.
This all sounds ugly, and it actually is. For now, it is definitely better to avoid that a station fails to start up. Generally, this should be possible, or do you have any special scenario where this error occurs regularly?
TDMA V2 shall solve this - someday...
Sorry .. forgot to add.. how has it been done for you guys for the server to wait for signals ?
Well, didn't get this yet. What kind of signals do you mean?
say if you want to check whether the sockets has data to read ? (this in Unix is dealt with poll or select). What would really happen if i used poll with rtnet APIs such as recvfrom_rt ? or mixing the two just doesn't really make sense.
No, makes absolutely no sense. The file descriptors used by RTnet (which are now managed by the RTDM module) are in an other domain than the standard Linux descriptors. Mixing them up in the RTnet implementation would easily break real-time constraints. That's why we need a dedicated poll_rt or select_rt...
Jan
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