Omron CJ2 CPU - REV 10-2010 User Manual page 378

10 CPU Unit Functions
CPU Operation during Program Replacement
The CPU Unit's operation will be as follows during program replacement:
• Program execution: Stopped
• Cycle time monitoring: No monitoring
Operations Continuing during and after Program Replacement
• When the IOM Hold Bit (A500.12) is ON, the data in the following memory areas will be main-
tained: the CIO Area, Work Area (W), Timer Completion Flags (T), Index Registers (IR), Data
Registers (DR), and the current EM bank number.
Note Timer PVs will be cleared during program replacement.
• If the IOM Hold Bit is ON when the program is transferred, loads that were being output before
program replacement will continue to be output after replacement. Be sure that external loads will
operate properly after program replacement.
• The status of force-set and force-reset bits will be maintained through the program replacement if
the Forced Status Hold Bit (A500.13) is ON.
• Interrupts will be masked.
• If data tracing is being performed, it will be stopped.
• Differentiation Flags will be initialized whether the IOM Hold Bit is ON or OFF.
Operations after Program Replacement
• The status of the cyclic tasks depends upon their operation-start properties. (Their status is the
same as it would be if the PLC were switched from PROGRAM to RUN/MONITOR mode.)
• The First Cycle Flag (A200.11) will be ON for one cycle after program execution resumes. (The
status is the same as it would be if the PLC were switched from PROGRAM to RUN/MONITOR
mode.)
Procedure
1
Mount a Memory Card containing the program file in the CPU Unit.
2
Set the Program File Name (A654 to A657) and Program Password (A651) in the Auxiliary Area,
and then turn ON the Replacement Start Bit (A650.15).
Additional Information
Turn ON the IOM Hold Bit (A500.12) if you want to maintain the status of I/O memory data
through the program replacement.
Turn ON the Forced Status Hold Bit (A500.13) if you want to maintain the status of force-set and
force-reset bits through the program replacement.
Precautions for Safe Use
If the IOM Hold Bit (A500.12) is ON before the program is replaced, the status of bits in I/O mem-
ory will be maintained after program replacement. Be sure that external loads will operate prop-
erly with the same I/O memory data.
If the Forced Status Hold Bit (A500.13) is ON before the program is replaced, the forced status in
I/O memory will be maintained after program replacement. Be sure that external loads will oper-
ate properly with the same forced status.
10-44 CJ2 CPU Unit Software User's Manual