Omron NY532-5400 User Manual page 266

9 Socket Service
 UDP Receive Processing
With UDP communications, the receive data that is stored in the receive buffer cannot be separated
and received. (The receive buffer holds up to 9,000 bytes.) Therefore, the data that is sent for each
send request must be received with one receive request. Because of this, attention must be given to
the following at the receiving node when data is received.
• When the Size of the Variable Specified in the Receive Request Is Smaller Than the Data Size
Sent with the Send Request
The received data that exceeds the size of the variable that is specified in the receive request is
discarded. All of the receive data is received if there is less data in the receive buffer than the size
of the variable that was specified in the receive request.
Example 1: Receive Request for 1,000 Bytes when 2,000 Bytes of Data Was Received
1. The data that was sent from the sending node in two sends is stored in the receive buffer.
2. If a receive request is made for 1,000 bytes for the first send data, the remaining 1,000 bytes is
discarded.
3. If the next receive request is for 2,000 bytes, all of the send data for the second send is received.
Sending node (host computer)
User program
2,000 bytes
2,000 bytes
9-8
Ethernet line
1st send
request
Data A
Data B
2nd send
request
NY-series Industrial Panel PC / Industrial Box PC Built-in EtherNet/IP Port User's Manual (W563)
Receiving node (Controller)
Built-in EtherNet/IP port
(1) Data received to
receive buffer.
(2) 1st receive
Receive buffer
(9,000 bytes)
Data A (upper bytes)
Data A (lower bytes)
Data B
(3) 2nd receive
4,000 bytes
User program
request (request
for 1,000 bytes)
1,000 bytes
Data A (upper bytes)
The remaining
data is discarded.
Data A (lower bytes) 1,000 bytes
request (request
for 2,000 bytes)
Data B 2,000 bytes