Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 71)

Publication 1785-UM024B-EN-P - January 2003
Monitoring and Troubleshooting Your ControlNet PLC-5 Hot Backup System 5-7
Troubleshooting
Qualification Crossloads If the data table structures are the same between the two processors,
data table crossloads automatically occur during qualification. Should
the Qualification Data Table crossloads fail, the processor major faults.
(Refer to Appendix C for more information on data table
crossloading.)
When a data table crossload fails, diagnostic information is stored in 2
words of the ControlNet Backup Configuration and Status file. Word
54 of this file contains the file number of the crossload that failed;
word 53 contains the error code indicating the reason why the
crossload failed. These error codes are identical to the Message
Instruction Error Codes. (See the Instruction Set Reference Manual,
Publication 6200-6.4.11 for a complete listing of the various error
codes which can be encountered while executing a Message
Instruction.)
For example, a qualification crossload could fail if the Data Table file
on the primary processor has read privileges disabled. This error
shows up as error code 0xF00B (privilege error) in word 53 of the
ControlNet Backup Configuration and Status file.
Troubleshooting with
Output Ownership
Verification When operating in hot backup mode, the ControlNet PLC-5 has
output ownership verification - a feature designed to notify the system
operator that output ownership has become divided between the
primary and secondary processors.
It is important to use this feature because it is possible for the
redundant connection between a primary processor and an output
module or adapter to become corrupted - possible causes could be a
high noise level environment and/or an improper network
installation. When this happens, the adapter will turn control of the
output over to the secondary processor without notifying the primary
processor that it has lost the connection.
TIP
If the file number of the crossload that failed (word
54 of the ControlNet Backup Configuration and
Status file) is 0xFFFF on the qualifying processor,
then the file number that failed is on the primary
processor.