9-5
9 Socket Service
NY-series Industrial Panel PC / Industrial Box PC Built-in EtherNet/IP Port User’s Manual (W563)
9-2 B
asic Kn
owledg
e on
Proto
cols
9
9-2-
2 Fr
agmenting of Send
Dat
a
The receive buffer for the built-in EtherNet/IP port is a maximum of 9,000 bytes per socket handle. If
any data that is larger than 9,000 bytes is received, any data over 9,000 bytes is discarded.
Up to 2,000 bytes can be received for a single request. In this case, the data is sent in fragments as
described below.
The conditions shown in the following figure occur when data is sent in fragments in TCP communica-
tions.
(1) A send request is sent from the user program at the sending node. It specifies a vari-
able with a data length of 2,000 bytes.
(2) The built-in EtherNet/IP port separates the send data into 1,024 bytes in data A and
976 bytes in data B.
(3) Data A and data B are sent in sequence by the sending node.
(4) After data A is received, the remaining data B is received.
Data in TCP communications is delivered to the user program in a fragmented form, as shown
above. The number of bytes of data that is received must be checked to confirm all data was
received before the next receive request is made. (You can use the
RecvDataSize
output variable of
the socket receive request instruction to check the received data.)
Additional Information
If TCP is used to send data to a different segment, the data is separated into 536-byte frag-
ments.
9-2-2
Fragmenting of Send Data
Using TCP
Built-in
EtherNet/IP port
User program
(5) Receives remaining 976 bytes.
(6) Receive request
(request for 2,000 bytes)
(3)
Data A and
data B are
sent in
succession.
(2) Fragmenting
(4) Receive request
Receiving node
2,000 bytes
2,000 bytes
1,024 bytes
1,024 bytes
976 bytes
976 bytes
Data A
Data A
Data A
Data B
Data B
Data B
Original data
User program
2,000 bytes
(1) Send request
Sending node (Controller)
Receiving node (host computer)
Ethernet line
Summary of Contents for Sysmac NY512-1300
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