_Examining the SmartSockets Toolkit_
by Douglass L. Campbell

Listing One

#define USER_DEVICE_DATA 2000
T_IPC_MT userDeviceDataMsgType;

struct userDeviceDataBuffer {
  T_INT2 fepId;
  T_INT2 chan;
  T_INT2 devAdr;
  T_INT2 numDataFields;
  struct {
    T_INT2 pointNum;
    T_INT4 pointVal;
    T_INT4 quality;
    T_INT4 dataTime;
  } data[];
};
//----------------------------------------------------------------
// CreateDeviceDataMsgType
// Create a user defined message type
//----------------------------------------------------------------
void CreateDeviceDataMsgType(void)
{
// Create message type. Grammar is used to allow message logging to an ASCII
// file. Curly braces in grammar indicate fields that can be repeated. 
// Message type: USER_DEVICE_DATA
// Purpose: Transport field device data
// Grammar: 
//   Fixed fields: 
//      int2 - FEP id
//      int2 - Channel
//      int2 - Device address
//   Repeated fields: 
//      int2 - Point number
//      int4 - Point value
//      int4 - Data quality flags
//      int4 - Value time tag
userDeviceDataMsgType = 
  TipcMtCreate("device_data",
               USER_DEVICE_DATA,
               "int2 int2 int2 {int2 int4 int4 int4}");
}
//----------------------------------------------------------------
// CreateUserDeviceDataMsg
// Create and return a UserDeviceData message.
//----------------------------------------------------------------
T_IPC_MSG CreateUserDeviceDataMsg(void)
{
T_IPC_MSG msg;
// Create a message to transport data
msg = TipcMsgCreate(userDeviceDataMsgType);
return msg;
}
//----------------------------------------------------------------
// LoadUserDeviceDataMsg
// Load a UserDeviceData message from the supplied buffer
//----------------------------------------------------------------
void LoadUserDeviceDataMsg(T_IPC_MSG msg, userDeviceDataBuffer* buf)
{
  TipcMsgAppendInt2(msg, buf->fepId);
  TipcMsgAppendInt2(msg, buf->chan);
  TipcMsgAppendInt2(msg, buf->devAdr);
  for (int x=0; x<buf->numDataFields; x++) {
    TipcMsgAppendInt2(msg, buf->data[x].pointNum);
    TipcMsgAppendInt4(msg, buf->data[x].pointVal);
    TipcMsgAppendInt4(msg, buf->data[x].quality);
    TipcMsgAppendInt4(msg, buf->data[x].dataTime);
  }
}

Listing Two

//--------------------------------------------------------------------------
// AcquireAndSendData. Get data from a channel and send it to other processes
//--------------------------------------------------------------------------
void AcquireAndSendData(void)
{
  T_IPC_MSG userDeviceDataMsg;
  userDeviceDataBuffer buffer;
  // create the new message type
  CreateDeviceDataMsgType();
  // create connection to the IPC manager
  TipcSrvCreate(T_IPC_SRV_CONN_FULL);
  // go get some data
  acquireData(buffer);
  // create a message to send data
  userDeviceDataMsg = CreateUserDeviceDataMsg();
  // load data into message
  LoadUserDeviceDataMsg(userDeviceDataMsg, buffer);
  // set message destination
  // this message goes to the logical "device_data" destination
  TipcMsgSetDest(userDeviceDataMsg, "device_data");
  // set GMD
  TipcMsgSetDeliveryMode(userDeviceDataMsg, T_IPC_DELIVERY_ALL);
  // send the message
  TipcSrvMsgSend(userDeviceDataMsg, TRUE);
}