User manual

Publication CNET-UM001C-EN-P - November 2005
Produce and Consume Tags (Interlock Controllers) 5-3
• the communication driver (such as., AB-PCICS-1) is configured for the
programming workstation.
Determine Connections for
Produced and Consumed
Tags
Logix controllers can produce (broadcast) and consume (receive)
system-shared tags that are sent and received via the ControlNet
communication module. Produced and consumed tags each require
connections.
All ControlNet modules support at least 32 connections. Additionally, the total
number of tags that can be produced or consumed is limited by the number of
available connections. If the communication module uses all of its connections
for I/O and other communication modules, no connections are left for
produced and consumed tags.
TIP
If you are only sharing tags between ControlLogix
controllers (the controllers are not controlling any I/O
modules), you can set the communication format of the
1756-CN2(R) or the 1756-CNB(R) module in the remote
chassis to None. This reduces connection usage and
network traffic.
This Type of Tag Requires These Connections
produced The produced tag requires two connections. The producing controller
must have one connection for the produced tag and the first
consumer and one more connection for each additional consumer
(heartbeat). The heartbeat is a small scheduled packet the consumer
sends to indicate that it is getting the produced data.
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.