Short summary

Name	`TCP_ServerOpen`
→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` )

Functionality

The block reserves an address and a port for the →TCP server .

Inputs, outputs, return value

	Identifier	→Data type	Description
Inputs:	`interfaceAddress`	`DWORD`	IP address to reserve
Inputs:	`interfacePort`	`UINT`	IP port to reserve
Outputs:	`serverHandle`	`TCP_ServerHandle`	handle of the reserved address and port
Return value:	`–` (= `rc` )	`TCP_ErrorCode`	returns the status of the TCP operation: `succeeded`: The operation is successful. `invalidHandle`: The handle is invalid. `cannotListenOnSocket`: Too many system resources are reserved. Reduce the usage of `TCP_ServerOpen`. `cannotCreateSocket`: The socket cannot be created. `cannotBindSocket`: The socket for the interface cannot be bound.

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

Internal error diagnostic for block

The block checks the following error cases:

The handle is invalid.
Too many system resources are reserved.
The socket cannot be created.
The socket for the interface cannot be bound.

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_Server
  USING logicals.system.network.tcp;
  VAR
    accptRC : TCP_ErrorCode := invalidHandle;
    serverCommData : tcpServerCommData;
    sendTestMsg : String[30] := 'Test Message';
    init : bool := true;
  END_VAR
 
  IF init THEN
    serverCommData.address := INET_ATON('127.0.0.1');
    serverCommData.port := 9999;
 
    TCP_ServerOpen(interfaceAddress:=serverCommData.address, interfacePort:=serverCommData.port, serverHandle=>serverCommData.serverHandle);
 
    init := false;
  END_IF;
 
  IF accptRC <> succeeded THEN
    accptRC := TCP_ServerAcceptConnection(serverHandle:=serverCommData.serverHandle, clientHandle=>serverCommData.clientHandle);
  ELSE
    TCP_Send(clientHandle:=serverCommData.clientHandle, data:=sendTestMsg);
  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.