Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 126)

Publication 1785-UM024B-EN-P - January 2003
ii
• ControlNet DIF and DOF files
• ControlNet Configuration file
• ControlNet Status file
• ControlNet Diagnostic file
Once this data table crossload is done, the secondary PLC-5
begins scanning its control program and a Phase 2 data
crossload operation begins. During this phase, the accumulator
elements of all timer and counter structures in the data table are
copied from the primary PLC-5 into the secondary PLC-5. This
transfer brings these dynamic values up-to-date in the operating
secondary. Once Phase 2 is complete, the secondary PLC-5 goes
into the qualified state and is ready to assume control in the
event that a switchover occurs.
This feature allows you to add an identical secondary PLC-5
onto an operating primary, and to easily bring the appropriate
contents of the secondary data table up to date. You can disable
this automatic feature by making the data table structures
different in the primary and secondary PLC-5s.
Note: While the secondary PLC-5 is in Run mode, it is your
responsibility to crossload data between the primary and
secondary PLC-5s as necessary, based on your application and
control program operation. See Phase 2 Data Crossload.
B
backup configuration and status
file
An integer file you create within both the primary and secondary
PLC-5s where backup configuration and status information is
stored.
bumpless transfer When a programmable controller switchover takes place in the
backup system and there is no adverse effect on system
operation, and the controlled process continues to run as
though it were still being controlled by the original primary
programmable controller.
C
ControlNet Backup Cartridge
(CHBM)
A memory cartridge (Cat. 1785-CHBM/A), similar to the
1785-M100 memory cartridge, that works in the ControlNet
PLC-5 Hot Backup system. This cartridge has two features the
1785-M100 cartridges does not have:
• Enables backup mode functionality within the
PLC5/ControlNet programmable controller.
• Provides 4 LED status indicators on backup operations.