Mitsubishi MELSEC QS Series, User Manual

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6
FUNCTIONS
6.11 Clock Function
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(5) Precautions
(a) Initial clock data setting
The clock data is not factory-set.
The clock data is used by the CPU module system for error
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operation history, etc.
When using the CPU module for the first time, be sure to set the precise time.
(b) Clock data when battery is low
The CPU measures the time even if the power fails module, using a battery
mounted on the CPU module.
Therefore, if the CPU module's battery capacity falls, the clock data value may
become inaccurate.
When the PLC power-on or the CPU module reset is canceled, the CPU module
checks if the clock data value is within the range shown in this Section (3).
If the clock data value is incorrect, the clock data value is initialized to January 1,
2005, 00:00:00.
At this time, the CPU module records OP004: "SYSTEM INITIALIZE SYSTEM
CLOCK" in the operation/error history.
(The time recorded in the operation/error history is the value of the clock data after
the clock data was initialized.)
(6) Accuracy of Clock Data
The accuracy of the clock function differs with the ambient temperature, as shown
below:
Table6.17 Accuracy of clock data
Ambient Temperature ( )
Accuracy (Day difference, S)
0 - 3.18 to + 5.25(TYP.+ 2.14)
+ 25 - 3.18 to + 5.29(TYP.+ 2.07)
+ 55 - 12.97 to + 3.63(TYP.-3.16)