Hi all, I have linux kernel 2.6.8.1, RTAI 3.1 and rtnet 0.8.3.
I try to realize a network with 3 pc, 1 master that sends packets to slaves in broadcast mode and 2 slaves that trasmit packets in two slots. The configuration file rtnet.conf is: # Primary master master: ip 192.0.0.241 cycle 600 slot 0 0 # Slave A slave: ip 192.0.0.235 slot 0 100 # Slave B slave: ip 192.0.0.244 slot 0 120 my machines are: master : PIII 450Mhz slaveA: PIII 533Mhz slaveB: PMobile 1600Mhz UDP packet size is 15byte, then a frame sends to channel has a size of 64byte. The time to send a frame is approximately 6us about 100Mb ethernet. When the systems run i have noticed that the first packet is delayed and the steady state is reached only after some cycles (6000us to slaveA, 3000us to slaveB). sequence of the transmission about channel is: time event 0 SOF 19us Master send a broadcast UDP packet 00, side of 15byte 600us SOF 1200us SOF 1800us SOF 2400us SOF 3000us SOF 3150us SlaveB responds with a UDP packet 3600us SOF 4200us SOF 4800us SOF 5400us SOF 6000us SOF 6120us SlaveA responds with a UDP packet 6600us SOF 6620us Master sends UDP packet 01 6700us SlaveA responds with a UDP packet 6720us SlaveB responds with a UDP packet 7200us SOF 7220us Master sends UDP packet 02 7300us SlaveA responds with a UDP packet 7320us SlaveB responds with a UDP packet etc.. 1) Anyone could tell me why this behaviour? My opinion is that the real behaviour would be the next: time event 0 SOF 19us Master send a broadcast UDP packet 00, side of 15byte 100us SlaveA responds with a UDP packet 120us SlaveB responds with a UDP packet 600us SOF 720us Master send a broadcast UDP packet 01, side of 15byte 800us SlaveA responds with a UDP packet 820us SlaveB responds with a UDP packet etc.. this behaviour no change when I have different UDP packet size (96byte or 256byte) 2) could I have a cycle time slower than 600us? now I can't use a cycle time slower than 600us, as the example above. 3) If It could be possible what is the real cycle time limit? thanks for all, best regards. ------------------------------------------------------- SF.Net email is sponsored by: Tame your development challenges with Apache's Geronimo App Server. Download it for free - -and be entered to win a 42" plasma tv or your very own Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php _______________________________________________ RTnet-users mailing list RTnet-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/rtnet-users
