A Dimarts 20 Març 2007 15:00, Jan Kiszka va escriure: > Leopold Palomo-Avellaneda wrote: > > ... > > Ok, > > > > thanks for the answer. I have to addmitt that to me all the documentation > > is a bit confuse for someone that begins in this area. Although there are > > a lot documents, I'm a bit lost. > > That's what we are gradually trying to improve via the wiki. Work in > progress, contributions of any form are welcome.
a Readme first ... > > My configuration is a normal PIII 550 with a rtai + rtnet and two > > ethernet. One to our lab and another to a stäubli controller. Both have a > > 100Mb card and are connected with a cross cable. > > > > If I unload the rtnet and I load the normal driver and I do a simple ping > > of 200 bytes I obtain this values: > > > > [EMAIL PROTECTED]:~$ ping -s 200 192.168.1.4 > > PING 192.168.1.4 (192.168.1.4) 200(228) bytes of data. > > 208 bytes from 192.168.1.4: icmp_seq=1 ttl=64 time=0.567 ms > > .... > > .... > > 208 bytes from 192.168.1.4: icmp_seq=48 ttl=64 time=0.523 ms > > .... > > 208 bytes from 192.168.1.4: icmp_seq=88 ttl=64 time=1.07 ms > > ...... > > 208 bytes from 192.168.1.4: icmp_seq=101 ttl=64 time=0.529 ms > > .... > > 208 bytes from 192.168.1.4: icmp_seq=140 ttl=64 time=0.540 ms > > ..... > > > > --- 192.168.1.4 ping statistics --- > > 158 packets transmitted, 158 received, 0% packet loss, time 157009ms > > rtt min/avg/max/mdev = 0.488/0.598/1.159/0.169 ms > > > > after ifdown, unload the module and loading the rtnet then: > > > > ulises:/usr/local/rtnet# sbin/rtping -s 200 192.168.1.4 > > Real-time PING 192.168.1.4 200(228) bytes of data. > > ..... > > 208 bytes from 192.168.1.4: icmp_seq=9 time=2547.4 us > > .... > > 208 bytes from 192.168.1.4: icmp_seq=24 time=3415.0 us > > .... > > 208 bytes from 192.168.1.4: icmp_seq=38 time=4722.8 us > > ..... > > 208 bytes from 192.168.1.4: icmp_seq=45 time=5356.8 us > > > > --- 192.168.1.4 rtping statistics --- > > 45 packets transmitted, 45 received, 0% packet loss > > worst case rtt = 8016.3 us > > > > > > could someone explain me this, because I understand that us are micro > > second (10^-6) so, this is worst in rt than in a normal net. > > If you picked the default setup via rtnet.conf, TDMA was activated at a > cycle period of 5 ms, one transmission slot per node and cycle. Thus you > get a latency of up to 2 x 5 ms. > > You can improve this by reducing the period or adding more transmission > slots per cycle. If you only want to use the RTnet link for RT traffic > and you have a collision-free media (cross-link or switched Ethernet), > you could also run RTnet without RTmac/TDMA. Writing a specialised RTmac > discipline (as a replacement for TDMA) is yet another option, but surely > a more complex one. Ok, I only want a simple thing. The problem is that I need the fastest low latency response as I can. I have only to send some bytes, no a lot of info. You comment something about to modify the tdma.conf file. I have this parameters: master: ip 192.168.1.3 cycle 5000 slot 0 0 slot 1 100 #slave: ip 192.168.1.3 #mac 00:C0:3A:25:01:OB mac 00:A0:C9:1D:52:B9 slot 0 2400 slot 1 2200 2/2 but I don't know if this are correct or not. > > However, it all melts down to scheduling your network traffic for hard > real-time use, not to make it simply as fast as possible, but to make it > fully predictable. Yes I know, but is a simple system: a PC with rtai and rtnet and a robot controller with vxworks. Regards, Leo ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ RTnet-users mailing list RTnet-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/rtnet-users
