10-25
10 CPU Unit Functions
CJ2 CPU Unit Software User’s Manual
10-3 Startup Settings and
Maintenance
10
10-3-3 Disabling Power OFF Interrupts
Areas of the program can be protected from power OFF interrupts so that they will be executed before
the CPU Unit is reset even if the power supply is interrupted. This is achieved by using the DISABLE
INTERRUPTS (DI(693)) and ENABLE INTERRUPTS (EI(694)) instructions.
This function can be used with sets of instructions that must be executed as a group, e.g., so that exe-
cution does not start with intermediate stored data the next time power is turned ON.
1 Set the Disable Setting for Power OFF Interrupts in A530 to A5A5 hex to enable disabling Power
OFF Interrupts.
2 Enable disabling Power OFF Interrupts in the PLC Setup (this is the default setting).
3 Use DI(693) to disable interrupts before the program section to be protected and then use
EI(694) to enable interrupts after the section. All instructions between DI(693) and EI(694) will be
completed before the Power OFF Interrupt is executed even if the power interruption occurs
while executing the instructions between DI(693) and EI(694).
z Auxiliary Area Flags and Words
10-3-3 Disabling Power OFF Interrupts
Procedure
Name Address Meaning
Disable Setting for Power OFF
Interrupts
A530 Enables using DI(693) to disable power OFF interrupt
processing (except for execution of the Power OFF Inter-
rupt Task) until EI(694) is executed.
A5A5 hex: Enables using DI(693) to disable power OFF
interrupt processing
Any other value: Disables using DI(693) to disable power
OFF interrupt processing
DI
EI
D
I
E
I
Execution condition
Interrupts disabled.
Power interrupted.
Instructions executed.
Interrupts enabled, causing
CPU Unit to be reset.
Power supply drops below
85% of rated value (80%
for DC power supplies).
Power interruption
detected.
CPU Unit
reset (forced
end)
Stop
Instructions executed
through EI(694).
Power OFF
detection time +
Power OFF
detection delay
10 ms - Power OFF
detection delay
(Power OFF
confirmation time)
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