Siemens SIMATIC S7 - Page 521

Libraries
9.4 Open user communication library
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
521
The UDP_RECV instruction also returns the IP address and port number of the remote
device. This allows your program to respond to the remote device with a UDP_SEND where
the remote IP address and port are required parameters.
Table 9- 20 Parameters of the UDP_RECV instruction
Parameter
Declaration
Data type
Description
EN
IN
BOOL
Enable input
ConnID IN WORD The CPU uses the Connection ID (ConnID) num-
ber for this receive operation (defined during the
connect process).
MaxLen IN WORD The MaxLen is the maximum number of bytes to
accept (for example, the size of the buffer at
DataPt (1 to 1024)).
DataPtr IN DWORD The DataPtr is the pointer to where the receive
data should be stored. This is an S7-200 SMART
pointer to I, Q, M, or V memory (for example,
&VB100).
Done OUT BOOL The instruction sets the Done output when the
receive operation is complete with no errors.
When the instruction sets the Done output, the
Length output is valid.
Busy OUT BOOL The instruction sets the Busy output while the
receive operation is in progress.
Error OUT BOOL The instruction sets the Error output when the
receive operation is complete with an error. Refer
to "Open user communication library instruction
error codes" (Page 524) for further information.
Status OUT BYTE The Status output shows the error code if the
instruction sets the Error output. Status is zero
(no error) if the instruction sets the Busy or Done
outputs.
Length OUT WORD The Length is the actual number of bytes re-
ceived. Only when the instruction sets the Done
or Error outputs is the Length valid. If the instruc-
tion sets the Done output, then the instruction
received the entire message. If the instruction
sets the Error output, the message was greater
than the buffer size (MaxLen) and has been trun-
cated.
IPaddr1
...
IPaddr4
OUT BYTE These are the four IP address octets of the re-
mote device that sent the message. IPaddr1 is
the most significant byte and IPaddr4 is the least
significant byte of the IP address.
RemPort OUT WORD The RemPort is the port number of the remote
device that sent the message.