Short summary

Name	`UDP_Open`
→POU type	→function
Category	more system blocks, network blocks , block with internal error diagnostic
Graphical interface
Available since	version 1.105.0 (for logi.CAD 3) and version 3.15.0 of logi.RTS This block is supported for these →target systems or platforms: →Raspberry Pi, →Revolution Pi platform `WindowsX86` (incl. the built-in PLC under Windows) version 1.109.0 (for logi.CAD 3) and version 3.19.0 of logi.RTS 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 releases the reserved address and port previously reserved by the block UDP_Open.

Inputs, outputs, return value

	Identifier	→Data type	Description
Inputs:	`address`	`DWORD`	IP address to reserve (in network byte order) Example: The IP address `127.0.0.1` must be specified as value `16#0100007F`. Use the `INET_ATON` block in order to convert the IP address.
Inputs:	`port`	`UINT`	IP port to reserve (in host byte order) Example: The IP port `1125` must be specified as value `1125`.
Outputs:	`rc`	`UDINT`	status of the UDP operation: `16#00000000`: The operation is successful. `16#80000007`: Too many system resources are reserved. Reduce the usage of `UDPOpen`. `16#81000003`: The system resources could not be reserved. `16#81000004`: The address and port could not be reserved.
Return value:	`–`	`DINT`	returns the handle of the reserved address and port

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:

Too many system resources are reserved.
The system resources could not be reserved.
The address and port could not be reserved.

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

Example for usage within ST-editor

Program with calls of UDP blocks

TYPE
  udpCommunicationData : STRUCT
    dstAddr : DWORD;
    dstPort: UINT;
    handle : DINT;
  END_STRUCT;
END_TYPE
 
PROGRAM ExampleUdpBlocks
  VAR
    udpCommData : udpCommunicationData;
    msg : STRING[56] := 'Text Message';
    receiveBuffer : STRING[100];
  END_VAR
        
  udpCommData.dstAddr := INET_ATON(hostAddr := '127.0.0.1');
      (* This example assumes that the IP-address '127.0.0.1' is registered in the ARP table.
         If not, the first ' UDP_Send' command will be used by the operating system to create the required entries in the ARP table.
         Mind that the first sent message might be lost. *)
  udpCommData.dstPort := 8888;
        
  udpCommData.handle := UDP_Open(address:=udpCommData.dstAddr, port := udpCommData.dstPort);
  UDP_Send(handle:=udpCommData.handle, lengthOfDataToSend := LEN(msg), data := msg, destinationAddress:=udpCommData.dstAddr, destinationPort := udpCommData.dstPort);
  UDP_Receive(handle:=udpCommData.handle, data:=receiveBuffer);
  UDP_Close(handle := udpCommData.handle);
END_PROGRAM

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.