Omron SYSMAC CJ1W-EIP21, Operation Manuals

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12 Communications Performance and Communications Load
12-4
CJ-series EtherNet/IP Units Operation Manual for NJ-series CPU Unit (W495)
The maximum number of connections for the EtherNet/IP Unit is 256.
The number of connections must be set to 256 or less combining both connections that the Unit opens
as the originator and connections that are opened from an originator with the Unit as the target.
Example:
Node 1 opens two connections as the target with node 2 and one connection as the originator with
node 3. Therefore, the total is three connections.
Node 2 opens two connections as the originator with node 1 and one connection as the originator with
node 3. Therefore, the total is three connections.
Node 3 opens one connection as the target with node 1 and one connection as the target with node 2.
Therefore, the total is two connections.
In either case, the connections can be opened because the maximum number of connections for the
EtherNet/IP Unit is 256 max.
Also, if multicast is set, one packet will be sent, but the number of connections will be consumed.
Example:
Node 3 sends one multicast packet to node 1 and node 2. Node 3 opens one connection as the target
with node 1 and one connection as the target with node 2.
Caution is required because the number of connections consumed is the same as for unicast connec-
tions even when multicast connections are set.
12-1-2 Calculating the Number of Connections
O
T
T
O
T
O
T
O
T: Target
O: Originator
Node 3 Node 2
Node 1
T
O
T
O
T: Target
O: Originator
Multicast
Node 3
Multicast
Node 2
Node 1