Allen-Bradley CompactLogix 5370 L1 User Manual

244 Rockwell Automation Publication 1769-UM021G-EN-P - October 2015
Chapter 9 Use I/O Modules with CompactLogix 5370 L3 Controllers
Module Fault Related to RPI Estimates
When following the guidelines described in Tab le 28, most CompactLogix 5370
L3 control systems operate as expected. Some systems that follow the guidelines
can experience a Module RPI Overlap minor fault as described in the
following table.
Name Fault
Information
Condition In Which Fault Occurs
Module
RPI
Overlap
(Type 03) I/O fault
(Code 94) Module
RPI overlap
detected
Module Slot = x,
where x is the slot
number of the I/O
module in the I/O
Configuration
section
This fault is logged when the current RPI update of an I/O module overlaps with its
previous RPI update. The Minor Faults tab in the Controller Properties dialog box
indicates in which module the RPI overlap occurs.
If multiple I/O modules experience the fault, the application indicates that the fault
occurred on the first such I/O module. Typically, it is an I/O module with a large
Input/Output array sizes. Example modules that use large Input/Output array sizes
include the 1769-SDN and 1769-HSC modules. In these cases, we recommend that
you adjust the RPI of the module to eliminate the fault.
Once the fault is cleared from the first I/O module, the application indicates the
next module that experiences the fault. This pattern continues until the fault is
cleared from all affected I/O modules.
To avoid this fault, set the RPI rate of the I/O modules to higher numerical values.
We recommend you use an RPI value that is not a common multiple of other
module RPI values, such as 2.5 ms, 5.5 ms, or 7 ms.
• We recommend that you do not run CompactLogix 5370 L3 control systems with
Module RPI Overlap faults.
• A system that experiences many Module RPI Overlap faults cannot operate
optimally because I/O data is not sampled at the expected rate that the RPI
settings determine.
• When the project is downloaded or the RPI value of an I/O module is adjusted, it
is expected to have a minor fault. Faults under these conditions are
transitionary. Clear the fault and wait for the fault to reappear before adjusting
the RPI value or the task priorities.

Allen-Bradley CompactLogix 5370 L1 Specifications

General

Brand	Allen-Bradley
Model	CompactLogix 5370 L1
Category	Controller
Language	English