TcpReceive

Description

This function block receives characters over a socket connection. It is possible that the number of characters actually received is less than the number expected. In that case, you will have to call the function again on the next cycle to receive the pending characters.

• 
  
• 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 If the socket is no longer valid then you must close it by using the TcpClose function block.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 9-1: The TcpReceive function block

Related Functions

TcpAccept, TcpBinReceive, TcpBinSend, TcpClose, TcpConnect, TcpIsConnected, TcpIsValid, TcpListen, 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 receive a string over a socket connection.
	Data Type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
ID	Description	The ID of the client socket
	Data Type	UDINT
	Range	N/A
	Unit	N/A
	Default	—
MaxChar	Description	The number of characters to receive.
	Data Type	STRING
	Range	N/A
	Unit	user units
	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
Data	Description	String of received characters
	Data Type	STRING

Example

Structured Text

(* 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;