Technical data

Rockwell Automation Publication 1769-TD005I-EN-P - August 2014 13
CompactLogix Controllers Specifications
You configure an RPI rate for the embedded I/O modules to establish specific time intervals at which data is transmitted
between the controller and the embedded I/O modules. The embedded I/O modules’ available RPI range is 0.5
…750.0 ms
and can be changed by 0.5 ms increments. The default setting is 20 ms.
To use 1769 Compact I/O modules as local expansion modules, keep in mind the following:
• Local expansion modules must be installed in the same system as the CompactLogix 5370 L2 controller.
• Local expansion modules are installed to the right of the embedded I/O modules.
• You must install a 1769-ECR Compact I/O end cap on the right side of control system. The end cap can be installed
on the right side of the embedded I/O modules or, if local expansion modules are used, on the right side of 1769
Compact I/O module.
CompactLogix 5370 L2 Controllers’ Local I/O Performance
The requested packet interval (RPI) defines the frequency at which the controller sends data to and receives data from I/O
modules. In the programming software, you set an RPI rate for each I/O module in your system, including embedded I/O
modules, local expansion modules, or distributed I/O modules over an EtherNet/IP network.
The CompactLogix 5370 L2 controllers always attempt to scan an I/O module at the configured RPI rate. The controller
scans distributed I/O modules at the configured RPI rates.
With embedded I/O modules and local expansion modules, however, some specific system configuration parameters
determine the actual rate at which the controller scans the modules. That is, the controller can be configured to scan an
I/O module at one rate, but actually scan the module at another rate.
For individual I/O modules, a Module RPI Overlap minor fault occurs if there is at least one I/O module that cannot be
serviced within its RPI time.
Local Expansion ModulesEmbedded I/O Modules