Omron Sysmac NX1P2-10 1 Series, User Manual

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Up to 2,000 bytes can be received for a single request. In this case, the data is sent in fragments as
described below.
Using TCP
The following figure shows what occurs when data is sent in fragments in TCP communications.
1. A send request is sent from the user program at the sending node. It specifies a variable with a
data length of 2,000 bytes.
2. The built-in EtherNet/IP port separates the send data into 1,024 bytes as data A and 976 bytes as
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.
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
Data is delivered to the user program in a fragmented form in TCP communications, as shown
above.
The size of received data must be checked to confirm that all the data was received before the
next receive request is made. (You can use the
RecvDataSize output variable of the socket re-
ceive 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.
Using UDP
The following figure shows what occurs when data is sent in fragments in UDP communications.
1. A send request is sent from the user program at the sending node. It specifies a variable with a
data length of 2,000 bytes.
9 Socket Service
9-5
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User’s Manual (W506)
9-2 Basic Knowledge on Protocols
9
9-2-2
Fragmenting of Send Data