UDP Management functions

The following functions enable management of UDP sockets for building client or server applications over ETHERNET network:

Parameter	Description
udpCreate	create a UDP socket
udpAddrMake	build an address buffer for UDP functions
updSendTo	send a telegram
udpRcvFrom	receive a telegram
udpClose	close a socket
udpIsValid	test if a socket is valid
updSendToArray	send a telegram
udpRcvFromArray	receive a telegram

Each socket is identified in the application by a unique handle manipulated as a DINT value.

Attention

Although the system provides a simplified interface, you must be familiar with the socket interface such as existing in other programming languages such as "C".
Socket management may be not available on some targets. Please refer to OEM instructions for further details about available features.

udpCreate: create a UDP socket

SOCK := udpCreate (PORT);

Inputs

Input	Data type	Description
PORT	DINT	IP port number to be attached to the server socket or 0 for a client socket.

Outputs

Output	Data type	Description
SOCK	DINT	ID of the new server socket.

This functions creates a new UDP socket. If the PORT argument is not 0, the socket is bound to the port and thus can be used as a server socket.

udpAddrMake: build an address buffer for UDP functions

OK := udpAddrMake (IPADDR, PORT, ADD);

Inputs

Input	Data type	Description
PORT	DINT	IP port number to be attached to the server socket or 0 for a client socket.
IPADDR	STRING	IP address in form xxx.xxx.xxx.xxx
PORT	DINT	IP port number.
ADD	USINT[32]	Buffer where to store the UDP address (filled on output).

Outputs

Output	Data type	Description
OK	BOOL	TRUE if successful.

This functions is required for building a internal UDP address to be passed to the udpSendTo function in case of UDP client processing.

udpSendTo: send a UDP telegram

OK := udpSendTo (SOCK, NB, ADD, DATA);

Inputs

Input	Data type	Description
SOCK	DINT	ID of the UDP socket.
NB	DINT	Number of characters to send.
ADD	USINT[32]	Buffer containing the destination UDP address (on input).
DATA	STRING	Characters to send.

Outputs

Output	Data type	Description
OK	BOOL	TRUE if successful.

The ADD buffer must contain a valid UDP address either constructed by the udpAddrMake function or returned by the udpRcvFrom function.

udpSendToArray: send a UDP telegram

OK := udpSendTo (SOCK, NB, ADD, DATA);

Inputs

Input	Data type	Description
SOCK	DINT	ID of the UDP socket.
NB	DINT	Number of characters to send.
ADD	USINT[32]	Buffer containing the destination UDP address (on input).
DATA	USINT[]	Array of characters to send.

Outputs

Output	Data type	Description
OK	BOOL	TRUE if successful.

The ADD buffer must contain a valid UDP address either constructed by the udpAddrMake function or returned by the udpRcvFrom function.

udpRcvFrom: receive a UDP telegram

Q := udpRcvFrom (SOCK, NB, ADD, DATA);

Inputs

Input	Data type	Description
SOCK	DINT	ID of the UDP socket.
NB	DINT	Maximum number of characters received.
ADD	USINT[32]	Buffer containing the UDP address of the transmitter (filled on output).
DATA	STRING	Buffer where to store received characters.

Outputs

Output	Data type	Description
Q	DINT	Number of actually received characters.

If characters are received, the function fills the ADD argument with the internal UDP of the sender. This buffer can then be passed to the udpSendTo function to send the answer.

udpRcvFromArray: receive a UDP telegram

Q := udpRcvFrom (SOCK, NB, ADD, DATA);

Inputs

Input	Data type	Description
SOCK	DINT	ID of the UDP socket.
NB	DINT	Maximum number of characters received.
ADD	USINT[32]	Buffer containing the UDP address of the transmitter (filled on output).
DATA	USINT[]	Array where to store received characters.

Outputs

Output	Data type	Description
Q	DINT	Number of actually received characters.

If characters are received, the function fills the ADD argument with the internal UDP of the sender. This buffer can then be passed to the udpSendTo function to send the answer.

udpClose: release a socket

OK := udpClose (SOCK);

Inputs

Input	Data type	Description
SOCK	DINT	ID of any socket.

Outputs

Output	Data type	Description
OK	BOOL	TRUE if successful.

You are responsible for closing any socket created by tcpListen, tcpAccept or tcpConnect functions, even if they have become invalid.

udpIsValid: test if a socket is valid

OK := udpIsValid (SOCK);

Inputs

Input	Data type	Description
SOCK	DINT	ID of the socket.

Outputs

Output	Data type	Description
OK	BOOL	TRUE if specified socket is still valid.

UDP Management functions

IEC 61131-3 Automation platform > Programming - Reference guide > Advanced operations > UDP Management functions

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