FCT_RECEIVE: Retrieves Data Available on a Socket

Function Description

The FCT_RECEIVE function looks for the data available on the socket. The maximum length of data to read is 240 bytes.

It returns the numbers of bytes read in the socket. You should always test this value \because it is the only way to check the actual number of data bytes stored in the user buffer.

NOTE: FCT_RECEIVE does not return out-of-band data.

The additional parameters and may be configured.

Representation in FBD

Representation in LD

Representation in IL

LD Module_Number

FCT_RECEIVE Socket_Number, Pbuf_Index, Gest_Index, Management_Param, Received_Data

Representation in ST

FCT_RECEIVE(Module_Number, Socket_Number, Pbuf_Index, Gest_Index, Management_Param, Received_Data);

Description of Parameters

The following table describes the input parameters:

Parameter	Type	Comment
Module_Number	INT	Slot number of network module in rack 0. Low byte is the slot number of the network module in rack 0. High byte can be used to extend the number of sockets. 00: Provided for full backward compatibility with applications created on firmware version 3.3 or earlier. 01: Up to 64 sockets can be used (firmware version must be higher than 3.3).
Socket_Number	INT	Socket number
Pbuf_Index	INT	Index of first word in Received_Data array
Gest_Index	INT	Index of first word in Management_Param array

The following table describes the output parameters:

Parameter	Type	Comment
Received_Data	ARRAY [0... n] OF INT	Array of maximum of 240 bytes containing the data read on the socket

The following table describes the input/output parameters:

Parameter	Type	Comment
Management_Param	ARRAY [0... 3] OF INT	Function management array The operation report can have the following values: 16#00: No error. 16#09: The socket number is invalid. 16#23: No data to read. 16#36: The connection has been reset by peer. 16#39: The socket is not connected (listening socket). 16#3C: The keep alive timed out on broken connection. 16#0E: The length of the character string to be received is greater than 240 bytes. The fourth word of the array should contain the number of bytes received if no error has occurred.