Allen-Bradley 1756 ControlLogix User Manual

Produce and Consume Tags (interlock controllers)
Chapter 5
Rockwell Automation Publication CNET-UM001F-EN-P - February 2018 77
Make sure of the following:
• The ControlNet communication modules are connected to a scheduled
ControlNet network.
• All wiring and cabling are properly connected.
• The communication driver is configured for the programming
workstation.
Tip:
If you are sharing tags only between ControlLogix controllers, the controllers are not controlling any I/O modules.
You can set the communication format of the 1756-CN2, 1756-CN2R, 1756-CNB, or 1756-CNBR modules in the
remote chassis to None. This limits connection usage and network traffic.
Logix controllers can produce (broadcast) and consume (receive) system-
shared tags that are sent and received via the ControlNet communication
module. Each produced and consumed tag requires connections.
Table 17 - Tag Type and Connections
Tag Type Required 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 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 available controller connections for other operations, such as communication and I/O.
Consumed Each consumed tag requires one connection for the controller that is consuming the tag.
All ControlNet modules support at least 32 connections. The number of
available connections limits the number of tags that can be produced or
consumed. 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.
Table 18 - Produced and Consumed Tags and Number of Connections
Controller
Available Connections
Connections Used by
a Produced Tag
Connections Used
by a Consumed
Tag
CompactLogix
PowerFlex 700S with
DriveLogix software
100 Number of consumers
+ 1
1
ControlLogix
SoftLogix5800
250
Determine
Connections for
Produced and
Consumed Tags

Allen-Bradley 1756 ControlLogix Specifications

General

Brand	Allen-Bradley
Model	1756 ControlLogix
Category	Controller
Language	English