Send/Receive Interface; Characteristic Data - Siemens SIMATIC NET S7-400 Manual

2.3

SEND/RECEIVE interface

2.3.1

Characteristic data

The SEND/RECEIVE interface provides access to communication using TCP, ISOonTCP,
ISO transport, email, and UDP connections. The following characteristics are important:
Characteristic
Number of SEND/RECEIVE connections
Number of SEND/RECV connections in
SPEED SEND/RECV mode
Maximum data length for AG_SEND and
AG_RECV program blocks
Maximum data length for AG_LSEND and
AG_LRECV program blocks
CP 443-1 (EX30)
Manual, 03/2019, C79000-G8976-C255-05
Explanation / values
TCP connections: 1...64
•
ISO-on-TCP connections: 1...64
•
ISO transport connections: 1...64
•
Total number of UDP connections (specified and free) that can be
•
configured: 1 to 64 (of those up to 48 in multicast mode)
Max. number of connections in total: Max. 64
•
(ISO transport + ISO-on-TCP + TCP + UDP)
Refer to the example in the section General characteristic data (Page 19).
Note on TCP connections: Avoiding receive overload
1)
The flow control on TCP connections cannot control permanent overload
of the recipient. You should therefore make sure that the processing ca-
pabilities of a receiving CP are not permanently exceeded by the sender
(approximately 150200 messages per second).
The number depends on the CPU type being used.
Per CPU 412/414 maximum 30
•
Per CPU 416/417 maximum 62
•
AG_SEND and AG_RECV were shipped with predecessors of the CP and
allow the transfer of user data with a length from 1 to 240 bytes. The
version of the CP described here continues to support these blocks.
AG_LSEND and AG_LRECV allow the transfer of user data with the fol-
lowing lengths:
ISO-on-TCP, TCP, ISO transport: 1 to 8192 bytes
•
UDP: 1 to 2048 bytes
•
E-mail (job header + user data): 1 to 8192 bytes
•
2.3 SEND/RECEIVE interface
1)
Performance data
21