Rockwell Automation 1757-ABRIO Process Remote I/O (RIO) Communication Interface Module - Manual (Page 147)

Publication 1757-UM007D-EN-P - December 2008 145
Operational Comparison Between the 1757-ABRIO Module and a PLC-5 System Appendix B
Exception Handling
Messages The 1757-ABRIO module provides a good communication flag for
each digital partial rack. It also maintains a good communication flag
for each configured block transfer module. These bits are set when
the rack or block transfer module is updating without errors, and are
cleared when an error occurs. These health bits are included in the
“Tag” along with the channel states.
In addition, the 1757-ABRIO module has underrange and overrange
bits for data on each channel for analog input modules. These are
treated as communication errors per channel setting outputs to
configured state (min, max, mid, last value) based on module
hardware jumpers.
These bits are included when you map a digital rack or block transfer
module to a flag read tag. Exceptions cause messages to be logged in
the scanner log.
Exception Conditions Comparison Between a PLC-5 System and a 1757-ABRIO Module
Exception Condition Message From 1757-ABRIO Perspective From the PLC-5 Perspective
No RIO network communication Good communication bits for all racks and all block
transfers are cleared and set to 0.
Digital Data does not update
Digital inputs hold their last state
Digital outputs go to the state set on the rack last state
switch in the rack
Block transfers do not update
Data from block transfer read modules is set to Not a
Number (NaN)
Block transfer write data goes to the state configured on
the I/O module (module dependent)
Tags with digital or block transfer data mapped to the
rack continue to update
Front panel displays a message for the last rack in error,
twice
RIO network status indicator is red
Status table bits for all racks are
cleared and set to 0.
Digital data does not update
Digital inputs hold their last state
Digital outputs go to the state set
on the rack last state switch
Block transfers do not update
Block transfer read data holds its
last state
Block transfer write data goes to
the state configured on the I/O
module
Error bits are set for all enabled
block transfer instructions