Mitsubishi Electric MELSEC iQ-R Series User Manual page 518

■Timing of the latch processing
The timing of the latch processing is determined based on the effective range of the latch interval setting and the operation
setting for the specified latch interval ( Page 514 Setting the latch interval)
• When set to "Time Setting"
Latch processing is started in the END processing executed after the set time.
Time setting
(For 10ms)
1 scan
Program
Write 100 to
D0 to D99.
Device memory
0
(Values from D0 to D99)
Backup power area
0
(Values from D0 to D99)
• The more the latch points, the more it takes to complete the latch processing. If the set time elapses while
latch processing is still executing, the next one is executed in the END processing that follows the
completion of the previous latch processing. Set a latch interval longer than the latch processing time so
that the specified time does not elapse during latch processing.
• If the latch interval is shorter than the scan time, latch timing occurs more than once within one scan.
However, latch processing is executed once during the END processing.
• When set to "Per Scan"
Latch processing is executed in the END processing of every scan. This setting allows to always retain the device of the
previous scan because the devices are latched at every scan. However, it may increase the scan time.
Each scan
Program
Write 100 to
D0 to D99.
Device memory
(Values from D0 to D99)
Backup power area
0
(Values from D0 to D99)
29 LATCH FUNCTION
516
29.1 Latch with Battery
10ms
Time elapsed
Write 200 to
D0 to D99.
100 200
Latch processing
1 scan
Latch
processing
Write 200 to
D0 to D99.
100
Data at this
time is latched.
Latch
100
processing
10ms
Time elapsed
Write 300 to Write 400 to
D0 to D99. D0 to D99.
300
Data at this
time is latched.
200
Latch processing
Powering off (resetting) the module at this time holds
D0 to D99 = 200.
1 scan
Latch
processing
Write 300 to
D0 to D99.
200
Data at this
time is latched.
Latch
200
processing
Powering off (resetting) the module at this time holds
D0 to D99 = 200.
400
Data at this
time is latched.
300
1 scan
Latch
processing
300
Data at this
time is latched.
Latch
300
processing