User manual

Publication 1768-UM001C-EN-P - November 2007
58 Configure and Monitor I/O
I/O Connections
A Logix5000 system uses connections to transmit I/O data.
Logix5000 Connection Types
Connection Description
Direct
(applies to all 1769 I/O)
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 between the controller and the
I/O module. Any break in the connection, such as a module
fault or the removal of a module while under power, causes
the controller to set fault status bits in the data area
associated with the module.
Typically, analog I/O modules, diagnostic I/O modules, and
specialty modules require direct connections.
Rack-optimized
(applies to distributed I/O)
For digital I/O modules, you can select rack-optimized
communication. A rack-optimized connection consolidates
connection usage between the controller and all of the
digital I/O modules on a rack (or DIN rail). Rather than having
individual, direct connections for each I/O module, there is
one connection for the entire rack (or DIN rail).