ConnectToTCPServer

int ConnectToTCPServer (unsigned int *conversationHandle, unsigned int portNumber, char serverHostName[], tcpFuncPtr callbackFunction, void *callbackData, unsigned int timeOut);

Purpose

Note  This function has been superseded by ConnectToTCPServerEx.

Establishes a connection between your program and a TCP server specified by a port number and server host name. Your program becomes a TCP client.

Thereafter, all messages from the server are routed through the specified client callback function.

Parameters

Input
Name	Type	Description
portNumber	unsigned int	The port number of the server to which to connect.
serverHostName	char []	The name of the host machine for the server. The name can either be an alphabetical string, such as xyz.natinst.com, or a numerical string, such as 123.456.7.8. If you pass NULL or an empty string, the server host is assumed to be the local machine.
callbackFunction	tcpFuncPtr	Pointer to the synchronous callback function that processes messages that your program receives as a TCP client. The callback function must be of the following form: int (*tcpFuncPtr) (unsigned handle, int xType, int errCode, void *callbackData); handle contains a value that is unique to each client-server connection. xType specifies the type of message the server sends. The client callback function can receive the following transaction types: TCP_DISCONNECT—Received when a server requests the termination of a connection or when a connection terminates because of an error. If the connection terminates because of an error, the errCode parameter contains a negative error code. TCP_DATAREADY—Received when there is data to be read by the client. Your program, acting as the client, calls ClientTCPRead to obtain the data. Note that this event is received again if you do not read all the available data. Use errCode only when the transaction type is TCP_DISCONNECT. Note    The return value of the callback is ignored. The callback function should be short and should return as soon as possible.
callbackData	void *	The name of the function that the TCP Support Library calls to process messages your program receives as a TCP client. callbackData is a pointer-width value the TCP Support Library passes to the callback function each time the library invokes the callback for the same client. You must define the meaning of the callback data. One way to use callbackData is as a pointer to a data object that you need to access in the callback function. By doing this, you can avoid declaring the data object as a global variable. If you do not want to use callbackData, you can pass zero.
timeOut	unsigned int	The number of milliseconds to wait before returning. For instance, if you pass a value of 100, the function returns an error if 100 milliseconds pass without the connection being established. If you pass zero, the function uses a default timeout of 5,000 milliseconds. Note   The host name lookup (if needed) is performed before starting the timeout countdown. For instance, if you pass a value of 100, and the hostname lookup takes 50 ms, the function might not return for up to 150 ms.
Output
Name	Type	Description
conversationHandle	unsigned int	The conversation handle that uniquely represents the connection between the server and the client. Note that zero (0) is a valid handle.

Return Value

Additional Information

Library: TCP Support Library

Include file: tcpsupp.h

LabWindows/CVI compatibility: LabWindows/CVI 3.0 and later