TcpIsConnected

Description

This function block tests if a client socket is connected.

• 
  
• It is possible that the socket becomes invalid if an error occurs in the TCP connection after this function block is called. You must use the TcpIsValid function block after TcpSend. If the socket is no longer valid then you must close it by using the TcpClose function block.

Figure 7-221: The TcpIsConnected function block

Related Functions

TcpAccept, TcpBinReceive, TcpBinSend, TcpClose, TcpConnect, TcpIsConnected, TcpIsValid, TcpListen, TcpReceive, TcpSend

Arguments

Input

Execute	Description	On the rising edgeA rising edge is the transition of a digital signal from low to high. It is also called positive edge test whether a socket is connected.
	Data Type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
ID	Description	ID of the client socket
	Data Type	UDINT
	Range	N/A
	Unit	N/A
	Default	—

Output

Done	Description	If TRUE, then the command completed successfully
	Data Type	BOOL
Error	Description	If TRUE, an error has occurred
	Data Type	BOOL
ErrorID	Description	Indicates the error if Error output is set to TRUE. See the table in Search IndexFile and TCP/IP Function Block ErrorID Output
	Data Type	DINT
Connected	Description	TRUE if connection is correctly established.
	Data Type	BOOL

Example

Structured Text

(* TcpIsConnected example *)
CASE StepCounter OF
0:
   Inst_TcpIsConnected(TRUE, MySocketID);
   StepCounter := StepCounter + 1;
1:
   Inst_TcpIsConnected(TRUE, MySocketID);
   IF Inst_TcpIsConnected.Done THEN
      MyTcpIsConnected := Inst_TcpIsConnected.Connected;
      Inst_TcpIsConnected(FALSE, 0);
      StepCounter := StepCounter + 1;
   END_IF;
END_CASE;