TcpReceive

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Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Receives characters over a socket connection.

Inputs

Input	Data Type	Range	Unit	Default	Description
Execute	BOOL	0, 1	N/A	No default	On the rising edge A rising edge is the transition of a digital signal from low to high. It is also called positive edge, receive a string over a socket connection.
ID	UDINT	N/A	N/A	No default	The ID of the client socket.
MaxChar	STRING	N/A	User units	No default	The number of characters to receive.

Outputs

Output	Data Type	Description
Done	BOOL	If TRUE, the command completed successfully.
Error	BOOL	If TRUE, an error has occurred.
ErrorID	DINT	Indicates the error if Error output is TRUE. See the table in Search IndexFile and TCP/IP Function Block ErrorIDs.
Data	STRING	String of received characters.

Remarks

It is possible that the socket becomes invalid if an error occurs in the TCP connection after this function block is called.
Use the TcpIsValid function block after TcpSend.
If the socket is no longer valid, close it using the TcpClose function block.

It is possible that the number of characters actually received is less than the number expected.
- In this case, call this function again on the next cycle to receive the pending characters.

Figure 6-284: TcpReceive

FBD Language Example

Not available.

FFLD Language Example

Not available.

IL Language Example

Not available.

ST Language Example

(* TcpReceive example *)
CASE StepCounter OF
0:
   Inst_TcpReceive(TRUE, MySocketID, 128);
   StepCounter := StepCounter + 1;
1:
   Inst_TcpReceive(TRUE, MySocketID, 128);
   IF Inst_TcpReceive.Done THEN
      ReceivedData := Inst_TcpReceive.Data;
      Inst_TcpReceive(FALSE, 0, 0);
      StepCounter := StepCounter + 1;
   END_IF;
END_CASE;