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Characteristic
Maximum data length for AG_LSEND and
AG_LRECV program blocks
Maximum data length for
AG_SSEND and AG_SRECV program blocks
LAN interface max. data field length generated
by CP per protocol data unit
Restrictions for UDP
• Transfer is not confirmed
The transmission of UDP frames is unconfirmed, in other words the loss of messages is not
detected or displayed by the send blocks (AG_SEND or AG_LSEND).
• No receipt of UDP broadcast
To avoid overload due to high broadcast load, the CP does not allow reception of UDP
broadcasts.
As an alternative, use the multicast function over a UDP connection. This allows you to
register the CP as a node in a multicast group.
• UDP frame buffering
Length of the frame buffer with buffering enabled:
2 KB
Note:
Following a buffer overflow, newly arriving frames are discarded.
2.3.2
Number of simultaneous SEND/RECEIVE calls
The number of SEND/RECEIVE calls that can be used at the same time is limited both by the
CPU and by the CP.
If the maximum number of simultaneous SEND/RECEIVE calls is exceeded, the value 8302H
(no receive resources) is indicated in the STATUS of the surplus SEND functions. This can, for
example, happen when too many SEND/RECEIVE calls are sent at the same time in OB1.
CP 442-1 RNA
Equipment Manual, 03/2022, C79000-G8976-C318-05
Explanation / values
AG_LSEND and AG_LRECV allow the transfer of user data with the
following lengths:
1. ISO-on-TCP, TCP, ISO transport: 1 to 8192 bytes
2. UDP: 1 to 2048 bytes
AG_SSEND and AG_SRECV allow the transfer of user data with the
following lengths:
1. ISO-on-TCP, TCP, ISO transport: 1 to 1452 bytes
2. UDP: 1 to 1452 bytes
•
sending
ISO transport, ISOonTCP, TCP:
–
400 bytes / TPDU with AG_SEND / AG_LSEND
1452 bytes / TPDU with AG_SSEND
–
•
receiving
ISO transport: 512 bytes / TPDU
–
ISO-on-TCP: 1452 bytes / TPDU
–
–
TCP: 1452 bytes / TPDU
Performance data
2.3 SEND/RECEIVE interface
21
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