Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 229

7 APPLICATION FUNCTIONS
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2) If an address in the link refresh range is specified, data is written to
that address when the instruction is executed, but the link device of the
network module is overwritten by the link device data of the CPU
module by the link refresh.
Make sure to write the same data to the link device of the CPU module
as well when writing by direct access (same for B, Y, SB and SW).
CPU
MOV K20 J1\W100
100
CPU
MOV K20 J1\W100
MOV K20 W100
100
(3) Differences from the link refresh
The following table shows how the direct access to link devices is different from
the link refresh.
For details, refer to the User's Manual (Function Explanation, Program
Fundamentals) of the CPU module used.
Item
Number of steps
Processing speed (LD BO – | | –)
Data reliability
1: For Q02HCPU
2: When the parameter of the station-based block data assurance is enabled.
3: When the 32-bit data assurance conditions are satisfied.
W
300
Link refresh
W
20
Link refresh
Access method
Link refresh
High speed (0.034 µs)
1
Per station
Network module
LW
100 20 to 300
Network module
LW
100 20
Direct access
1 step
Low-speed (several 10 µs)
2-word units (32 bits)
2
MELSEC-Q
2 steps
3
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