9 Socket Service
9-8
NY-series Industrial Panel PC / Industrial Box PC Built-in EtherNet/IP Port User’s Manual (W563)
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.
1st send
request
2nd send
request
Data B
2,000 bytes
Data A
2,000 bytes
Data B
Data A (upper bytes)
Data A (lower bytes)
4,000 bytes
Data B
Data A (upper bytes)
Data A (lower bytes)
1,000 bytes
2,000 bytes
1,000 bytes
Built-in EtherNet/IP port
User program
Sending node (host computer)
Receiving node (Controller)
Receive buffer
(9,000 bytes)
User program
Ethernet line
(1) Data received to
receive buffer.
(2) 1st receive
request (request
for 1,000 bytes)
(3) 2nd receive
request (request
for 2,000 bytes)
The remaining
data is discarded.
Summary of Contents for Sysmac NY512-1300
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