[RTnet-users] TDMA: management time slot

Andrea Forni Thu, 23 Mar 2006 05:57:19 -0800

Hi all,

for the first: I'm sorry for my english...

I have linux kernel 2.6.10.0, RTAI 3.1 and rtnet 0.8.3.

I'm realizing a communication between a node master and a node slave: slave send

n (in this case n=200) message to master with a similar code:

///////////////////////////////////////////////////////////////// C O D E S L A V E ///////////////////////////////////////////////////////////////////////

#include "stdio.h"
#include "stdlib.h"
#include "time.h"
.
.
. /* include */
.

#define TIMERTICKS 500000

using namespace std;

RTIME periodo;

int main()

{

      static struct sockaddr_in local_addr;
      static struct sockaddr_in pc3_addr;
      static struct sockaddr_in pc2_addr;
      static struct sockaddr_in pc4_addr;

      int sockfd = 0;
      int ret    = 0;
      int i=0; //contatore del ciclo del task
      int len;
      int nuovo = 1000;

      long long timeout; //variabile per gestire timeout della funzione "recv"
      timeout=2000000; //variabile per gestire timeout della funzione "recv"

      char buf[10]= "virtus";

      RT_TASK *task; // nome task

//################################################## A D D R E S S #######################################################

          memset(&local_addr, 0, sizeof(struct sockaddr_in));
          memset(&pc3_addr, 0, sizeof(struct sockaddr_in));
          memset(&pc2_addr, 0, sizeof(struct sockaddr_in));
          memset(&pc4_addr, 0, sizeof(struct sockaddr_in));

   local_addr.sin_family      = AF_INET;
          local_addr.sin_addr.s_addr = INADDR_ANY;
   local_addr.sin_port        = htons(atoi("50000")); //setta porta locale

   pc3_addr.sin_family = AF_INET;
   pc3_addr.sin_addr.s_addr = inet_addr("10.0.0.3");
          pc3_addr.sin_port = htons(atoi("3000")); //setta porta pc3

          pc2_addr.sin_family = AF_INET;
   pc2_addr.sin_addr.s_addr = inet_addr("10.0.0.2");
          pc2_addr.sin_port = htons(atoi("2000")); //setta porta pc3

          pc4_addr.sin_family = AF_INET;
   pc4_addr.sin_addr.s_addr = inet_addr("10.0.0.4");
          pc4_addr.sin_port = htons(atoi("40000"));


      mlockall(MCL_CURRENT|MCL_FUTURE);

//############################################### S O C K E T ############################################################

      sockfd = socket_rt(AF_INET, SOCK_DGRAM, 0);
      .
      .
      .

//############################################### I O C T L ##############################################################

      ioctl_rt(sockfd, RTNET_RTIOC_EXTPOOL, &nuovo);

//############################################ T A S K   I N I T ##########################################################

      task = rt_task_init(4800, 1, 0, 0);
      .
      .
      .


      rt_make_hard_real_time();


     //########################################## B I N D #############################################

     bind_rt(sockfd, (struct sockaddr *) &local_addr, sizeof(struct sockaddr_in));

     //####################################### T I M E O U T #############################################

     ioctl_rt(sockfd, RTNET_RTIOC_TIMEOUT, &timeout);


//############################################### W H I L E ##############################################################

     while(i<200)

   {
      sendto_rt(sockfd, buf, sizeof(buf), 0, (struct sockaddr*)&pc3_addr, (socklen_t)sizeof(sockaddr));

      i++;

    }

//############################################### C L O S E ##############################################################

     rt_make_soft_real_time();

     close_rt(sockfd);

     rt_task_delete(task);

     return 1;

}

//////////////////////////////////////////////////////////// E N D C O D E ///////////////////////////////////////////////////////////////////

(the code for master is similar)

I organise tdma.conf file in this mode:

# Primary master
    master:
    ip 10.0.0.3
    cycle 1000
    slot 0 200
    slot 2 600

# Slave A
    slave:
    ip 10.0.0.1
    slot 10 0
    slot 2 400

I would that the slave send two message (RT) to master in one cycle of TDMA. I hope to read that, for example :

time event

0 synchronization TDMA
10 slave(10.0.0.3) send a message to master(10.0.0.1)
200 master receive a message from slave
400 slave send a message to master
600 master receive a message from slave
1000 synchronization TDMA
1010 slave(10.0.0.3) send a message to master(10.0.0.1)
1200 master receive a message from slave
1400 slave send a message to master
1600 master receive a message from slave
2000 synchronization TDMA
.
.
.
.
.

in the reality I have this situation:

time event

0 synchronization TDMA
10 slave(10.0.0.3) send a message to master(10.0.0.1)
200 master receive a message from slave
1000 synchronization TDMA
1010 slave(10.0.0.3) send a message to master(10.0.0.1)
1200 master receive a message from slave
2000 synchronization TDMA
.
.
.
.
.

I'm searching to do a control in an automation system and I need to send a message to master very quickly (100-150us for the moment), for this motif I do the tests above...
I read in old mails (and I verify this) that a cycle of 600us is stressfull for the network,but for my situation I must to send a message in shorter time(100-150us), for this
I would to poll a node more than one time in the cycle.

thanks for all, Ciao

Andrea

[RTnet-users] TDMA: management time slot

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