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 mxfA717RxAcqRead() function. The mxfA717NextDataRecordPtrGet() function needs to be used to navigate in the receive buffer.

The MXF_A717_DATAREC structure must be used to read ARINC 717 messages with acquisition service.

Example

The example below shows how to implement an ARINC 717 basic receive acquisition application.

ar717.c

#define MAX_TX_SUBFRAMES_TO_TRANSMIT     4

uint32                  rc;
HMXF_CHANNEL            rxChannel;
size_t                  rxBufferSize;
HMXF_BUFFER             rxBuffer;
MXF_A717_DATAREC*       rxHostBuffer;
uint64                  rxAcqStatus;
uint64                  msgCount;
uint64                  byteCount;
uint64                  data;
uint64                  word;
MXF_A717_DATAREC*       rec;

   ...

   // Allocates buffer for rx data
   if(!rc)
   {
      rxBufferSize = MAX_TX_SUBFRAMES_TO_TRANSMIT*sizeof(MXF_A717_DATAREC);

      // Allocates RX acquisition static buffer
      rc=mxfRxAcqBufferAlloc(rxChannel, rxBufferSize, &rxBuffer, NULL);

      // Host buffer allocation
      if(!rc)
      {
         rxHostBuffer = (MXF_A717_DATAREC*) calloc(1, rxBufferSize);
         if(!rxHostBuffer)
            rc = MAXT_ERROR_MEM;
      }
   }

   // Starts acquisition
   if(!rc)
      rc = mxfRxAcqStart(rxBuffer, MXF_RXACQ_FLAG_DEFAULT, 0, 0);

                              ...

   if(!rc)
   {
      printf("Receiving ...\n");
      // Reads rx buffer
      rc = mxfA717RxAcqRead(rxBuffer, 0, rxBufferSize, &rxAcqStatus, &msgCount, &byteCount, rxHostBuffer);
   }

   if(!rc)
      printf("String received count = %llu \n", msgCount);

   if(!rc)
   {
      // Displays received strings
      rec = rxHostBuffer;
      for(data=0; data<msgCount && !rc; data++)
      {
         printf("%02llu: Timetag=%012llu, Size=%u words\n", data, rec->timeTag, (rec->dataSize)/2);
         for(word=0; word < subframeSize; word++)
            printf("%03X ", rec->data[word]);
         printf("\n");
         mxfA717NextDataRecordPtrGet(rec, &rec);
      }
   }

   // Stops acquisition
   if(!rc)
      rc = mxfRxAcqStop(rxBuffer);

                                        ...