9-17
9 PLC Setup
CJ2 CPU Unit Software User’s Manual
9-3 PLC Setup Settings
9
9-3-3 Timings/Synchronous Set-
z Power OFF Detection Delay Time
This parameter is used to set the power OFF detection delay time to a value other than 0 ms.
Note This parameter is not supported when the CJ1W-PD022 Power Supply Unit is mounted.
Power OFF Detection Delay Time
This parameter determines how much of a delay there will be from the detection of a power interrup-
tion until a power interruption is established and the regular program is stopped. The setting can be
between 0 and 10 ms.
Extend the time until detection of a power interruption when momentary interruptions in a bad power
supply are causing PLC operation to stop. It takes a maximum of 10 ms for the internal 5-VDC
power supply to drop to 0 VDC after the initial power interrupt detection time.
This 10 ms is the power
supply holding time. It is equal to the power OFF detection time plus the processing time required to confirm the
power interruption. The power OFF delay time is 10 to 25 ms (not consistent) for AC power supplies, 2 to 5 ms
for CJ1W-PD025 DC Power Supply Units, and 2 to 10 ms for CJ1W-PD022 DC Power Supply Units.
Note This parameter is not supported when the CJ1W-PD022 Power Supply Unit is mounted. (Refer to A-5 Oper-
ation for Power Interruptions.)
Note The execution time of the program in the power OFF interrupt task must be less than 10 ms minus the power
OFF detection delay time. For information on power OFF interrupt tasks, refer to 5-2-3 Interrupt Tasks. For
information on operation at power OFF, refer to A-5 Operation for Power Interruptions.
Parameter Settings Default Function
Related
flags and
words
Power Off
detection
time
0 to 10 ms
(1-ms units)
0 ms This setting determines how much of a delay there will
be from the detection of a power interruption (approxi-
mately 10 to 25 ms for AC power and 2 to 5 ms for DC
power after the power supply voltage drops below 85%
of the rated value) to the confirmation of a power inter-
ruption. The default setting is 0 ms.
When the power OFF interrupt task is enabled, it will be
executed when the power interruption is confirmed. If
the power OFF interrupt task is disabled, the CPU will
be reset and operation will be stopped.
---
100% of rated power supply voltage
AC: 85%
(DC: 80%)
Power OFF
detection
delay time
0 to 10 ms
Regular program
Time
Power OFF
interrupt task
Stop
Default power OFF
detection time:
AC: 10 to 25 ms
DC: 2 to 5 ms
(not consistent)
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