23 LATCH FUNCTION
23.1 Latch with Battery
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23 LATCH FUNCTION
23.1 Latch with Battery
The data in each device/label of the CPU module is cleared to its default value in the following cases:
• When the CPU module is powered off and on
• When the CPU module is reset
• When a power failure exceeding the allowable momentary power failure time occurs
The data in each device/label with latch setting is retained by using the battery on the CPU module unit even under the above
described conditions. For this reason, control can be continued with the retained data even if the power of the CPU module is
turned off or a power failure exceeding the allowable momentary power failure time occurs while the data is managed by a
sequential control.
The R00CPU, R01CPU, and R02CPU retain the data in each device/label with latch setting without a battery
during power failure.
The other programmable controller CPUs retain the data in each device/label with latch setting without a
battery during power failure by inserting a battery-less option cassette to the CPU module. ( Page 394
Latch with Battery-less Option Cassette)
Types of latch
The following types of latch are available:
• Latch (1): Data in this range can be cleared by a latch clear operation
• Latch (2): Data in this range cannot be cleared by a latch clear operation
• When using the Process CPU (redundant mode), refer to the following as well.
Page 435 FUNCTIONS
• When using the SIL2 Process CPU, refer to the following as well.
Page 605 FUNCTIONS
• When using the Safety CPU, refer to the following as well.
Page 535 FUNCTIONS
RnCPU
RnENCPU
RnSFCPU RnSFCPU
RnPSFCPU RnPSFCPU
RnPCPURnPCPU
(Standard) (Safety)(Standard) (Safety)
(Redundant)
(Process)
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