Omron Sysmac NX1P2-10 1 Series, Руководство пользователя

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1st send
request
2nd send
request
Data A
Data B
1,000 bytes
2,000 bytes
Data A
Data B
1,000 bytes
2,000 bytes
3,000 bytes
Data A
Data B
1st receive request
(Request for 1,000 bytes)
2nd receive request
(request for 2,000 bytes)
Ethernet line
Built-in EtherNet/IP port
User program
Sending node (host computer)
Receiving node (Controller)
Receive buffer
(9,000 bytes)
User program
(1) Data received to
receive buffer.
(2) The data is received in
two sections.
UDP Receive Processing
In UDP communications, receive data stored in the receive buffer (a maximum of 9,000 bytes) cannot
be divided to be received.
Therefore, if data is sent for one send request, it must be received with one receive request.
The following must be considered to receive data at the receiving node.
• When the Size of the Variable Specified in the Receive Request Is Smaller Than the Data Sent with
the Send Request
If receive data exceeds the size of the variable specified in the receive request, the excess of the
data is discarded.
If the data in the receive buffer is smaller than the size of the variable specified in the receive re-
quest, the entire receive data is received.
Example 1: 1,000-Byte Receive Request Is Made for 2,000-Byte Data
1. The data is divided to be sent in two sends from the sending node, and is stored in the receive
buffer.
2. If a 1,000-byte receive request is made for the first send, the remaining 1,000 bytes of the data is
discarded.
3. If the next receive request is made for 2,000 bytes, the data for the second send is all received.
9 Socket Service
9-7
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User’s Manual (W506)
9-2 Basic Knowledge on Protocols
9
9-2-3
Data Receive Processing