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4. If a power interruption occurs during initialization or execution of the power
ON interrupt program, restart continuation will begin at initialization or from
the beginning of the power ON interrupt program.
5. Timers are stopped when a power interruption occurs and their PVs are
maintained. The timers begin counting again when the power OFF interrupt
program is executed, and are once again stopped with PVs maintained
when the power OFF interrupt program is completed.
Timing begins again when the main program is started. Timers are held dur-
ing initialization and execution of the power ON interrupt program.
6. An I/O interrupt program will be executed from the instruction just after the
one that was being executed when the power interruption signal was output,
just like the main program.
When power returns, all I/O interrupts will be masked, so the masks will have
to be removed with MSKS(153) in the power ON interrupt program if the in-
terrupts are to operate.
7. Scheduled interrupts are cancelled by a power interruption, so reset sched-
uled interrupts in the power ON program if necessary.
8. If SE(214)/SOFF(215) are executed in the power ON interrupt program,
main program execution will start from the active step with the highest prior-
ity.
9. When power is interrupted, the address being executed is recorded in the
CPU and program execution proceeds from the next address when the PC
is restarted. The program on the Memory Card must therefore be identical to
the one in the PC if the program is automatically transferred from the
Memory Card when power returns to the PC. If the program has been
changed, the PC might not operate properly.
10. If the DIP switch on the CPU is set to transfer the program from the Memory
Card on power-up, the PC Setup will be transferred at the same time. Be
sure that any important changes to the PC Setup are recorded in the version
of the PC Setup on the Memory Card.
The following parameters are maintained when the PC is restarted.
1, 2, 3...
1. Active status of steps
2. Execution status of interrupt programs
3. The cause of interrupt programs received before the power interruption (ex-
cept for power OFF interrupt program)
4. The address being executed in the program
5. Interlock status
6. IOM (I/O memory) status
7. Forced Set/Reset status (if PC Setup and A00013 are set to maintain forced
status)
8. Timer and counter PVs
9. Step timer PVs
10. Elapsed time for AQ (L, D, SL, SD, DS)
11. Trace execution status
12. Trace initial start, when the PC Setup is set for Trace execution on power-up
13. Arithmetic Flag status saved with CCS(173)
14. Index register contents
15. The current EM bank number
Note Even if the current EM bank number is changed in the power OFF in-
terrupt program, the EM bank number will revert to the one that was
valid just before the power OFF interrupt program was executed.
Parameters Maintained for
Restart Continuation
PC Operation Section 6-1
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