Mitsubishi Electric MELSEC iQ-R Series User Manual page 31

Differences from link refresh
Item
Number of steps
*1
Processing speed
Cyclic data assurance
*1 For actual values, refer to the following.
 MELSEC iQ-R Programming Manual (Module Dedicated Instructions)
Shortening the link refresh time and transmission delay time
■Shortening the link refresh time
Remove infrequently used link devices from the link refresh range, and directly read or write the corresponding data using link
direct devices. This function reduces the number of the link refresh points to the CPU module, resulting in a shorter link
refresh time. (Page 24 Link refresh)
■Shortening the transmission delay time
Because the link direct device allows direct reading or writing of data to the link devices of the RJ71LP21-25 at the time of the
instruction execution, the transmission delay time can be shortened.
Link refresh is executed in END processing of the sequence scan of the CPU module.
Precautions
■Cyclic data assurance
Direct access to link devices does not provide station-based block data assurance. Use 32-bit data assurance, or if cyclic data
of more than 32 bits needs to be assured, use interlock programs. ( Page 79 Precautions for Programming)
■Mounting multiple modules of the same network number
When multiple RJ71LP21-25s of the same network number are mounted, the target of direct access is the module which has
the smallest slot number in the base unit.
Access method
Link refresh
1 step
High speed
Available
Direct access
2 steps
Low speed
Not available
1 FUNCTIONS
1.1 Cyclic Transmission Function
1
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