Allen-Bradley 1756 ControlLogix User Manual

Control I/O
Chapter 4
Rockwell Automation Publication CNET-UM001F-EN-P - February 2018 61
Table 9 - Communication Formats
Communication Format
with a Remote ControlNet
Communication Module
Criteria for Use
None
• When all of the remote I/O communicating with a controller via the remote ControlNet
communication module use a Direct Connection communication format
• When the connection is used for scheduled peer interlocking
• When I/O will be mostly direct connections
• When multiple controllers control the outputs in the chassis
Rack-optimized
• When some or all of the remote I/O communicating with a controller via the remote
ControlNet communication module use a rack-optimized communication format
• To minimize ControlNet network bandwidth when using large volume of digital I/O
• If only one controller will control the I/O
Rack-optimized—Listen only When some or all of the remote I/O communicating with a controller via the remote
ControlNet communication module use a rack-optimized communication format
I/O module type determines the available communication formats.
Table 10 - Communication Format for Module Types
I/O Module Type Desired Connection Required Communication Format
Digital module Rack-optimized connection Rack-optimized
Direct connection or to use specialty
features of the module, such as
diagnostics, timestamps, or electronic
fuses
or
Connection for listening to data from the
module
• The data your controller needs from the I/O module. For
example, if your application uses a 1756-IA16I module in a
remote chassis that must provide timestamped input data,
choose the CST Timestamped Input Data communication
format.
• A listen-only communication format that matches the data
the I/O module is broadcasting to other controllers.
Analog module Direct connection or to use specialty
features of the module, such as
diagnostics, timestamps, or electronic
fuses
or
Connection for listening to data from the
module
• The data your controller needs from the I/O module. For
example, if your application uses a 1756-OF6CI module in a
remote chassis that must provide floating point output data,
choose the Float Data communication format.
• A listen-only communication format that matches the data
the I/O module is broadcasting to other controllers.

Allen-Bradley 1756 ControlLogix Specifications

General

Brand	Allen-Bradley
Model	1756 ControlLogix
Category	Controller
Language	English