Rockwell Automation 5720 DriveLogix System - Manual (Page 46)

Publication 20D-UM002C-EN-P - November 2003
2-12 What Is DriveLogix?
The controller has the following limits on the number of connections that you
can cache:
Determining Connections
for I/O Modules The DriveLogix system uses connections to transmit I/O data. These
connections can either be direct connections or rack-optimized connection.
Over ControlNet, I/O connections are scheduled connections:
Connections for local I/O modules
The DriveLogix controller automatically assigns one rack-optimized
connection for the local DIN rail. You then configure each I/O module on the
DIN rail to either use that rack-optimized connection or to use a direct
connection. The rack-optimized connection for the DIN rail exists whether or
not you configure the I/O modules to use that rack-optimized connection.
The rack-optimized connection lets you organize all the digital I/O modules
on the DIN rail into one connection to the controller. Or you can choose to
configure each I/O module to have a direct connection to the controller.
Analog I/O modules must have a direct connection to the controller.
It is not as critical to manage the number of connections for local I/O
modules as it is for remote devices because the controller supports a direct
connection for each possible local I/O device.
If you have this software
and firmware revision: Then you can cache:
11.x or earlier • block transfer messages for up to 16 connections
• other types of messages up to 16 connections
12.x or later up to 32 connections
Connection: Description:
direct 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.
rack-optimized 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 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).