Short summary

Name	`TCP_Connect`
→POU type	→function
Category	more system blocks, network blocks , block with internal error diagnostic
→Namespace	`logicals.system.network.tcp`
Graphical interface
Available since	version 3.2.2 (for library `Standard` ) This block is supported for these target systems or platforms: Raspberry Pi, Revolution Pi platform `WindowsX86` (incl. the built-in PLC under Windows) platform `LinuxX86`

Functionality

The block establishes a connection to a →TCP server.

Inputs, outputs, return value

	Identifier	→Data type	Description
Inputs:	`destinationAddress`	`DWORD`	destination IP address
	`destinationPort`	`UINT`	destination IP port
	`interfaceAddress`	`DWORD`	network interface IP address
	`interfacePort`	`UINT`	network interface IP port
Outputs:	`clientHandle`	`TCP_ClientHandle`	handle of the reserved address and port
Return value:	`rc`	`TCP_ErrorCode`	returns the status of the TCP operation: `succeeded`: The operation is successful. `cannotCreateSocket`: The socket cannot be created. `cannotBindSocket`: The socket for the interface cannot be bound. `cannotConnectToServer`: The connection to the server cannot be established.

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic .

Internal error diagnostic for block

The block checks the following error cases:

The socket cannot be created.
The socket for the interface cannot be bound.
The connection to the server cannot be established.

In such an error case, the output ENO of the block is set to value FALSE (or an equivalent). Moreover, the block returns the appropriate code (see the above table).

Example for usage within ST-editor

Program with calls of TCP blocks

PROGRAM TCP_Client
  USING logicals.system.network.tcp;
  VAR
    rcTCPConnect : TCP_ErrorCode := invalidHandle;
    clientCommData : tcpClientCommData;
    receiveTestMsg : STRING[30] := '';
    init : bool := true;
  END_VAR
 
  IF init THEN
    clientCommData.serverAddress := INET_ATON('127.0.0.1');
    clientCommData.serverPORT := 9999;
  END_IF;
 
  IF rcTCPConnect <> succeeded THEN
    rcTCPConnect := TCP_Connect(destinationAddress:=clientCommData.serverAddress, destinationPort:=clientCommData.serverPORT, clientHandle=>clientCommData.clientHandle);
  ELSE
    TCP_Receive(clientHandle:=clientCommData.clientHandle, data:=receiveTestMsg);
  END_IF;
END_PROGRAM
 
TYPE
  tcpServerCommData : STRUCT
    address : DWORD;
    port : UINT;
    serverHandle : logicals.system.network.tcp.TCP_ServerHandle;
    clientHandle : logicals.system.network.tcp.TCP_ClientHandle;
  END_STRUCT;
 
  tcpClientCommData : STRUCT
    serverAddress : DWORD;
    serverPORT : UINT;
    clientHandle : logicals.system.network.tcp.TCP_ClientHandle;
  END_STRUCT;
END_TYPE

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.