TCP/IP: ITcIoTcpProtocol(Recv)

The ITcIoTcpProtocol and ITcIoTcpProtocolRecv interfaces enable TCP/IP communication from the real-time environment.

A project that uses this interface contains a pointer to an ITcIoTcpProtocol object and implements ITcIoTcpProtocolRecv itself. ITcIoTcpProtocolRecv serves as a callback interface for receiving data and events from the TCP/IP module within the application. The interfaces are based on a socket API.
Before a socket can be used, it must be allocated with AllocSocket().

ITcIoTcpProtocolRecv methods:

Name	Description
ReceiveData	Is called by the TCP/UDP RT module as a callback to transfer data.
ReceiveEvent	Is called by the TCP/UDP RT module as a callback if an event has occurred.

ITcIoTcpProtocol methods:

Name	Description
AllocSocket	Allocates a socket.
FreeSocket	Enables a socket.
Connect	Establishes a connection to a remote terminal.
IsConnected	Indicates whether a socket is connected (for inbound and outbound connections).
Close	Closes a socket.
Listen	Opens a TCP port for incoming connections (see remarks).
Accept	For server functionality: Accepts incoming connections (see remarks).
SendData	Sends data (server and client functionality).
CheckReceived	Must be called cyclical; ReceiveEvent and ReceiveData are used as callback in the context of this method (server and client functionality).
GetRemoteIpAddr	Returns the remote IP address of a communication partner.
GetFreeSendDataSize	Returns the number of free bytes in the TCP send buffer.

	Call CheckReceived() continuously.

	Perhaps call AllocSocket() again in the event of an OnlineChange, in order to refresh the callback target.

The client and server implementation process is described here, independent of programming languages.
Only an overview is provided; the samples illustrate the application.

Implementation of an TCP server:

Name	Description
AllocSocket	Opens a socket.
Listen	Opens a port on which connections are expected.
Accept	Is called in the ReceiveEvent() method in order to accept a connection.
ReceiveData	Is called when data are received.
SendData	Can be used to send data.
FreeSocket	On the Listen socket and all connection sockets for stopping.

Code diagram for accepting a connection:

HRESULT CIpStackDemo::ReceiveEvent(ULONG socketId, TCPIP_EVENT tcpEvent)...
case TCPIP_EVENT_CONN_INCOMING:
m_spTcpProt->Accept(socketId);
break;

Implementation of a TCP client:

Name	Description
AllocSocket	Opens a socket.
Connect	Starts connection establishment.
IsConnected	Checks whether the connection was established successfully.
ReceiveData	Is called when data are received.
SendData	Can be used to send data.
FreeSocket	On the Listen socket and all connection sockets for stopping.

	Disconnection by the operating system in Promiscuous mode If Promiscuous mode is active at the RT Ethernet adapter in the “Adapter” tab, any TCP connection attempts are blocked by the operating system, since it does not recognize a port opened in the TCP/UDP RT object.

Further Information