15 LATCH FUNCTION
15.5 Precautions
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15
15.5 Precautions
The precaution to be taken when using a latch function is described below.
• When latch range and device no. of points are changed in the parameter, the latching for devices other than link register
(W) and latch label will be the same as the latch settings before the change. Also, if the latch range setting parameter at the
time of previous operation is different from that at the time of the current operation after the CPU module is powered OFF
and ON or reset, the latch data is recovered only in the overlapping part of the latch ranges.
• When latch range and the number of devices are changed in the parameter, all latch labels are cleared to "0".
• When the CPU parameter, program file, FB file, and global label setting file are changed, all latch labels are cleared to "0".
However, when SM9353 (clear/keep of latch labels during PC write) is ON, even if the program file, FB file, and global label
setting file are changed, latch labels are not cleared.
* 1
• Special relays and special registers are not cleared even by performing CPU memory operation or special relay clearing.
• Extended file register (ER) cannot be cleared by special relays (SM8031, SM8032). Use ERINIT instruction, and data batch
initialization (clearing values/memory initialization) function of GX Works3 when you clear an extended file register (ER).
(Page 68 Extended file register (ER) function)
*1 To keep the data of latch label, turn on SM9353 before changing the files. Note that SM9353 can back up the setting in the event of a
power interruption, and the setting can be backed up once SM9353 is turned on.
For supported version of SM9353 (clear/keep of latch labels during PC write), refer to Page 942 Added and Enhanced Functions.
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