Siemens Simantic Net NCM for Industrial Ethernet S7 - Manual (Page 151)

Programming FCs (Functions) and FBs for S7 Ethernet CPs
151
SIMATIC NET NCM S7 for Industrial Ethernet
C79000-G8976-C129–06
Working with the Job Header
Free UDP connections require a job header in the user data area.
The following schematic illustrates the structure of the job buffer and the meaning
and location of the parameters in the job header.
Job header
User data
User data area
Job buffer
03
H
(high byte) EB
H
(low byte)
0B
H
8E
H
23
H
28
H
Data byte 2041 Data byte 2040
Bytes 0,1
Bytes 2,3
Bytes 4,5
Bytes
2046,2047
Data byte 1 Data byte 0
Bytes 6,7
Port
IP address
Figure 5-1 Sending and Receiving on a Free UDP Connection with Programmed Addresses
S
In the picture (entries in hexadecimal) the following IP address is assumed:
142.11.40.35 (example only);
S For the port address 1003, the following would be entered: for low byte: EB
H
;
for high byte: 03
H.
S
The user data area can be up to 2048 bytes long. Up to 2042 bytes of user data
can be transferred. 6 bytes are reserved for the job header.
Please note that the data length specified in the block call (LEN parameter)
must include the header and the user data!