Broadcasting - Omron NJ501-1300 User Manual

9 Socket Service
• When There Is Only One Receive Request for Data Sent for Multiple Send Requests
You cannot use just one receive request to receive the data that was sent for multiple send
requests, regardless of the size of the data.
Example 2: Receive Request for 1,000 Bytes when 200 Bytes of Data Was Sent for Two Send
1. The data that was sent from the sending node in two sends is stored in the receive buffer.
2. Even if a receive request is made for 2,000 bytes of data, only the 100 bytes that was sent for the
first send request is received.
Sending node (Controller)
User program
100 bytes
100 bytes
9-2-4

Broadcasting

You can set the destination IP address to a broadcast address for a UDP socket to broadcast data to
the host and all nodes on the same network as the Ethernet/IP port. If there is a router on the network,
packets are not sent beyond the router. You can broadcast up to 1,472 bytes of data. Data larger than
1,472 bytes cannot be broadcast.
You can specify either of the two following types of broadcast addresses.
• Local Broadcast
If no destination IP address is specified, the following IP address is specified automatically.
Network segment: The network segment of the local IP address is set.
Host segment: All bits are set to 1.
• Global Broadcast
Specify this type when the IP address of the local node or the subnet to which the local node belongs
is unknown. As shown below, every bit of the 32-bit address is set to 1.
255.255.255.255
9-8
Requests
Ethernet line
1st send
request
Original
data
Original
data
2nd send
request
Receiving node (host computer)
Receiving node
(1) Data received to
receive buffer.
Receive buffer
(9,000 bytes)
Original
data
Original
data
200 bytes
NJ-series CPU Unit Built-in EtherNet/IP Port User's Manual (W506)
User program
(2) 1st receive request
(request for 1,000
bytes)
Original
data
100 bytes
You can receive the rest
of the data with another
receive request.
Original
data