Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 103)

Publication 1785-UM024B-EN-P - January 2003
Data Table Crossloading C-5
– ControlNet I/O Status File
– ControlNet Diagnostic File
Optimizing On-Demand Crossloads
When setting up the backup system, the location of the data that
needs to be crossloaded is important. We recommend that you place
all of the crossload data into a few consecutively-addressed files.
Then, by configuring those files in the range User Selectable crossload
files, only those files will be crossloaded. This shortens the time
necessary to perform the crossload, as well as preventing unwanted
files from being crossloaded.
For example, if there are 10 integer files that need to be crossloaded,
place those 10 integer files into consecutively numbered files (e.g.
N100 through N109). Then fill the User Defined Crossload Range Low
File (Word 57 of the CHBI file) with 100 and the User Defined
Crossload Range High File (Word 58 of the CHBI file) with 109. Now
all 10 integer files will be crossloaded when User Selected File
operation of the On-Demand data table crossload is triggered.
Triggering an On-Demand Data Table Crossload
On-Demand data table crossloads are initiated by writing a value into
the On-Demand crossload command word (word 33 of the ControlNet
Backup Integer File). The On-Demand data table crossload can be
initiated from either the primary or secondary processor.
Since the On-Demand crossload command word is located in an
integer file, you have many options concerning how the On-Demand
data table crossload gets triggered. The crossload could be triggered
via the ControlNet Backup Configuration and Status tool, via the
RSLogix5 Data Monitor, or via ladder logic in your application.
IMPORTANT
If a file in the On-Demand crossload User Selectable
files is either a Timer or Counter file type, only the
Accumulator for each file element is crossloaded.
The timer and counter presets are not crossloaded. If
you want them to be crossloaded, you must use a
different crossloading mechanism.