Sending Periodic Messages

The basic logic to send periodic messages is as follows:

• First, create a schedule instance for a given channel using mxfTxPeriodicScheduleNew().
• Before adding the CSDB records to the message, at least one buffer list must be added with mxfTxPeriodicScheduleBufferListAdd(). The function includes an argument to specify how many buffers (CSDB data) the list will contain. If the list includes more than one buffer, one CSDB record for each buffer included in the list will be sent back-to-back at the message update rate.
• Many buffer lists can be added to a message if desired. The function mxfTxPeriodicScheduleBufferListAdd() includes an argument to specify a time delay to be inserted between two consecutive buffer lists.
• Set the CSDB data in the MXF_CSDB_DATAREC for a given record using mxfCSDBTxPeriodicUpdateMsgWrite().
• Start the schedule using mxfTxPeriodicScheduleRun().

The example below illustrates how to put it together:

csdb_periodic.c

#define BUFFER_SIZE     4096 // 4KB
#define TX_MSG_LABEL    5
#define TX_MSG_SI       0
#define BLOCKCOUNT      6

HMXF_CHANNEL txChannel;
HMXF_BUFFER  txBuffer[2];
MXF_CSDB_DATAREC *recCsdb=NULL;
HMXF_SCHED schedule;
HMXF_SCHED_MSG msg=0;
HMXF_SCHED_MSG_BUFFER msgBuf=0;
uint32 rc;

   ...

   // Allocate TX Periodic Update buffer
   if(!rc)
      rc = mxfTxPeriodicUpdateMsgBufferAlloc(txChannel, 0xA5, BUFFER_SIZE, &txBuffer[0], NULL);

   if(!rc)
      rc = mxfTxPeriodicUpdateMsgBufferAlloc(txChannel, TX_MSG_LABEL, BUFFER_SIZE, &txBuffer[1], NULL);

   // Allocate host buffer
   if (!rc)
   {
      recCsdb = (MXF_CSDB_DATAREC*)malloc(BUFFER_SIZE);
      if (!recCsdb)
         rc = MAXT_ERROR_MEM;
   }   

   // Create the periodic scheduler
   rc = mxfTxPeriodicScheduleNew(txChannel, &schedule);

   // Set scheduling values: Rate=100 ms (.1sec), Phase=0 us
   if(!rc)
      rc = mxfTxPeriodicScheduleMsgAdd(schedule, 100000LL, 0, &msg);

   // Define the number of buffer for the list and link to it
   if(!rc)
      rc = mxfTxPeriodicScheduleBufferListAdd(msg, 2, 0, txBuffer);

   // Set record for the buffers
   // Set the sync block
   if(!rc)
   {
      recCsdb->timeTag = 0;
      recCsdb->control = 0;
      recCsdb->repeatCount = 1;
      recCsdb->reserved = 0;
      for (i=0; i<BLOCKCOUNT; i++)
         recCsdb->data[i] = 0xa5;
      rc = mxfCSDBTxPeriodicUpdateMsgWrite(txBuffer[0], 1, recCsdb);
   }

   // Set the message block
   if(!rc)
   {
      recCsdb->timeTag = 0;
      recCsdb->control = 0;
      recCsdb->repeatCount = 1;
      recCsdb->data[0] = TX_MSG_LABEL;
      recCsdb->data[1] = TX_MSG_SI;
      for (i=2; i<BLOCKCOUNT; i++)
         recCsdb->data[i]= (uint8)i;
      recCsdb->reserved=0;
      rc = mxfCSDBTxPeriodicUpdateMsgWrite(txBuffer[1], 1, recCsdb);
   }

   //  Run the scheduler, update records
   if(!rc)
   {
      printf("Running periodic transmission, please wait...\n\r");

      // Runs the schedule now
      rc = mxfTxPeriodicScheduleRun(schedule);
   }

   // Wait 10 seconds
   if(!rc)
   {
      mxfSleep(10000);

      rc = mxfTxPeriodicScheduleFree(schedule);
   }

   if(recCsdb)
      free(recCsdb)

   ...