Rockwell Automation Logix5000 Controllers I/O and Tag Data Programming Manual - Manual (Page 13)

Communicate with I/O modules Chapter 1
formats. Each format uses a different data structure. The communication format
that you choose also determines:
• Direct or rack-optimized connection on page 13 .
• Ownership on page 14 .
Direct or rack-optimized connection
The Logix5000 controller uses connections to transmit I/O data. These
connections can be direct connections or rack-optimized connections.
Term Definition
Direct connection 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.
Rack-optimized connection 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).
Rock well Automati on Publication 1756- PM004E -EN-P - October 2014 13