Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 44)

Publication 1785-UM024B-EN-P - January 2003
3-18 Installing and Configuring Your ControlNet PLC-5 Backup System
Advanced Configuration
Options The procedures in the previous sections outlined the steps required to
configure a basic ControlNet PLC-5 backup system. In addition, there
are other options you can configure for the backup system. In
addition to the information provided here, you can find specific
details on these features in the appendices of this manual.
• Synchronous and Asynchronous modes - provide you with
the opportunity to choose synchronous or asynchronous
program scanning for your backup system.
• Equivalence Checking - when enabled, equivalence checking
is the performance of verification checks to ensure the
qualifying secondary matches the primary. The current
equivalence status of the two processors is displayed.
Note: If equivalence checking is enabled during qualification
and differences are found, a major fault will occur on the
qualifying PLC-5.
• Crossloading - allows you to perform an on-demand transfer of
data files from the primary to the secondary processor
• Forced Switchover - allows you to force the primary processor
to secondary, and vice versa, on demand. This option is
available while both PLC processors are in Run mode. To force a
switchover, simply click on the Force Switchover button on the
Status tab of the ControlNet Hot Backup screen.
• System Status - provides you with informational messages and
current system status
• Crossload Data over Data Highway Plus - you can crossload
Data Table files over Data Highway Plus via channel 1 A. By
default, Data Table file crossloading is done over the ControlNet
channel.
This ability allows crossloading without affecting the ControlNet
channel. This may be desirable when the unscheduled
bandwidth of the ControlNet channel is so busy that any
additional traffic may cause network problems.
Requalification Option of Dual Primary Programmable
Controllers - you can select to requalify a ControlNet PLC-5 in
a Hot Backup system where dual primary programmable
controllers exist. This will avoid a potential major fault.
Additionally, this feature increases the availability of a qualified
backup system if communication is broken and later restored
between the two programmable controllers.