Direct Or Rack-Optimized Connection; Ownership - Allen-Bradley 1756-L61 ControlLogix 5561 Programming Manual

Communicate with I/O Modules

Chapter 1

Term

Direct connection

Rack-optimized connection

The Logix5000 controller uses connections to transmit I/O data. These

connections can be direct connections or rack-optimized connections.

Definition

A direct connection is a real-time, data transfer link between the controller and an I/O module. The controller maintains

and monitors the connection with the I/O module. Any break in the connection, such as a module fault or the removal

of a module while under power, sets fault bits in the data area associated with the module.

A direct connection is any

connection that does not use the

Rack Optimization Comm Format.

For digital I/O modules, you can select rack-optimized communication. A rack-optimized connection consolidates

connection usage between the controller and all the digital I/O modules in the chassis (or DIN rail). Rather than having

individual, direct connections for each I/O module, there is one connection for the entire chassis (or DIN rail).

Rack-Optimized Connection

In a Logix5000 system, modules multicast data. This means that multiple devices

can receive the same data at the same time from a single device.

Rockwell Automation Publication 1756-PM004D-EN-P - September 2012

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