Mitsubishi Electric MELSEC-Q00U(J)CPU User Manual page 125

(4) Latch interval setting
Data are latched at each scan or at set intervals. Latch timing is set in
(a) Each scan
Latch data processing is performed during END processing of each scan. Since device data is latched every
scan, the CPU module holds the latest device data at all times.
(b) Time setting
Latch data processing starts during the first END processing after a preset time has elapsed. Since the latch
data processing is performed asynchronous to the sequence program, an increase in scan time is reduced.
If the latch interval is shorter than a scan time, the latch timing occurs more than once within one scan. However, the latch
processing is performed only once during the END processing.
(5) Latch setting
To latch data, a latch range and timing need to be set.
(a) Latch range setting
Latch-target devices and ranges are set. There are two range settings: the latch clear operation enable range
setting (Latch (1)) and the latch clear operation disable range setting (Latch (2)).
Project window
Set the start and end device numbers.
● If "Use the same file name as the program" is selected in the PLC File tab of the PLC parameter dialog box, latch ranges
of the file register (ZR), extended data register (D), and extended link register (W) cannot be set. (All data in the file
register (ZR) will be held.) The data outside the latch range will be cleared when the CPU module is powered off and on
or is reset.
● When the file register file used is switched with the QDRSET instruction, the latch range setting of the file register will be
disabled. After switching, regardless of the latch range setting, all data in the file register will be held.
Note 3.1
Universal
Only the High-speed Universal model QCPU and Universal model Process CPU can select "Time Setting" in parameter.
The latch interval setting is fixed to "Each Scan" for other CPU modules.
Note 3.1
[Parameter] [PLC Parameter]
CHAPTER 3 FUNCTIONS
parameter.Note 3.1
Device tab
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