Rockwell Automation 1789-L10_L30_L60 SoftLogix 5800 System User Manual - Manual (Page 38)

38 Rockwell Automation Publication 1789-UM002J-EN-P - December 2012
Chapter 2 What is the SoftLogix System?
How the SoftLogix System
Uses Connections The SoftLogix system uses a connection to establish a communication link
between two devices. Connections can be any of the following:
• Controller to local I/O modules or local communication modules
• Controller to remote I/O or remote communication modules
• Controller to remote I/O (rack-optimized) modules
• Produced and consumed tags
• Messages
You indirectly determine the number of connections the controller uses by
configuring the controller to communicate with other devices in the system.
Connections are allocations of resources that provide more reliable
communication between devices than unconnected messages.
Connections for Produced
and Consumed Tags The SoftLogix controller supports the ability to produce (multicast) and
consume (receive) system-shared tags. System-shared data is accessible by
multiple controllers over an EtherNet/IP network. Produced and consumed tags
each require scheduled connections.
The SoftLogix controller supports a maximum of 127 consumed connections.
For two controllers to share produced or consumed tags, both controllers must be
attached to the same network. You cannot bridge produced and consumed tags
between two networks.
Connections for Messages Messages transfer data to other devices, such as other controllers or operator
interfaces. Some messages use unscheduled connections to send or receive data.
These connected messages can leave the connection open (cache) or close the
Tag Type Required Connection
Produced By default, a produced tag allows two other controllers to consume the tag, which means that as
many as two controllers can simultaneously receive the tag data. The local controller (producing)
must have one connection for the produced tag and the first consumer and one more connection
for each additional consumer (heartbeat). The default produced tag requires two connections.
As you increase the number of controllers that can consume a produced tag, you also reduce the
number of connections the controller has available for other operations, like communication and I/
O.
Consumed Each consumed tag requires one connection for the controller that is consuming the tag.