Basic Acquisition

The way to set a basic acquisition receive application is as follows:

• A receive channel must be obtained using the mxfModuleChannelGet() function or with the mxfModuleChannelAllGet() function by specifying the MXF_SCLASS_RXACQ_SRV subclass.
• The acquisition buffer must be allocated using the mxfRxAcqBufferAlloc() function.
• The acquisition mode can be set using the mxfRxAcqModeSet() function.
  
  Two modes of acquisition are defined;
  
  

  Condition	Description
  MXF_RXACQ_MODE_LINEAR	In this mode the acquisition stops when the buffer is full.
  MXF_RXACQ_MODE_CIRCULAR	In this mode the acquisition buffer is circular and never stops receiving. Whenever the acquisition queue becomes full, the acquisition process will discard the newest received record.

• The acquisition must be started using the mxfRxAcqStart() function.
• A read loop can be implemented using the mxfA429RxAcqRead() function and the data received decoded using the mxfA429ArwDecompose() function.

The MXF_A429_DATAREC structure must be used for reading an ARINC 429 message with acquisition service.

Example

ar429_periodic.c
The example below shows how to implement an ARINC 429 basic receive acquisition application.

#define BUFFER_SIZE 4096

HMXF_CHANNEL rxChannel;
HMXF_BUFFER rxBuffer;
MXF_A429_DATAREC *rec429=NULL;
MXF_A429_DATAREC *recPtr=rec429;
uint64 status, msgsCount, bytesCount;
uint64 j;
uint32 label, sdi, data, ssm, parity;
uint32 rc;

  ...

   // Allocates RX acquisition buffer
   if (!rc)
      rc = mxfRxAcqBufferAlloc(rxChannel, BUFFER_SIZE, &rxBuffer, NULL);

   // Allocates host buffer
   if (!rc)
   {
      rec429 = (MXF_A429_DATAREC*)malloc(BUFFER_SIZE);
      if (!rec429)
         rc = MAXT_ERROR_MEM;
   }

   // Starts the acquisition process
   if (!rc)
      rc = mxfRxAcqModeSet(rxBuffer, MXF_RXACQ_MODE_LINEAR);
   if (!rc)
   {
      rc = mxfRxAcqStart(rxBuffer, MXF_RXACQ_FLAG_DEFAULT, 0, 0);
      if (!rc)
         printf("\nAcquisition started\n\r");
   }

   ...

   // Reads and displays records
   rc = mxfA429RxAcqRead(rxBuffer, 0, BUFFER_SIZE, &status, &msgsCount, &bytesCount, rec429);
   for (j=0; j<msgsCount && !rc; j++)
   {
      rc = mxfA429ArwDecompose(recPtr->data, &label, &sdi, &data, &ssm, &parity);
      if(!rc)
      {
         printf("%02llu: Timetag %llu - ARINC word=[%03llo,%lld,%05llX,%lld,%s]\n",
                  j, recPtr->timeTag, label, sdi, data, ssm, (parity==VMXF_A429_PARITY_ODD)?"ODD":"EVEN");
         if(!rc)
            rc = mxfA429NextDataRecordPtrGet(recPtr, &recPtr);
      }
   }

   ...