Mitsubishi Electric MELSEC iQ-R Series User Manual page 37

Differences from link refresh
Item
Number of steps
Processing speed
Cyclic data assurance
*1 For the instruction processing time when using link direct devices (J\), refer to the following.
MELSEC iQ-R Programming Manual (CPU Module Instructions, Standard Functions/Function Blocks)
Shortening the transmission delay time
The transmission delay time can be shortened by reducing the number of link refresh points and shortening a communication
cycle interval. (Page 275 Communication cycle interval)
The following methods can be used to reduce the number of the link refresh points.
• In "Refresh Settings" under "Basic Settings", set only the link devices that are frequently used in the CPU module in the link
refresh range. (Page 100 Refresh Settings)
• Remove the link devices that are infrequently used in the CPU module from the link refresh range, and directly read/write
the corresponding data from/to the program by direct access.
Link refresh is performed in END processing of the sequence scan of the CPU module.
Precautions
■ Cyclic data assurance
The direct access to link devices does not provide station-based block data assurance. (Page 35 Cyclic data assurance)
■ Mounting multiple modules of the same network number
When multiple modules of the same network number are mounted, the target of the direct access to link devices is the module
that has the smallest slot number in the base unit.
■ Link direct device in a multiple CPU system
In a multiple CPU system, link direct devices cannot be used for the CC-Link IE Controller Network-equipped module
controlled by another CPU module.
■ When conducting a link direct access to a link device assigned to the Motion control station
• The value written to RY/RWw assigned to the motion control station is not reflected in the output to the motion control
station. Additionally, when operating in multicast mode, the value written to RY/RWw assigned to the motion control station
is not stored in the local station link device (RX/RWr).
• When reading RX/RWr assigned to the motion control station, the value (initial value 0) written last by direct access, etc. of
the link device is read.
Access method
Link refresh
1 step
High speed
Available
Direct access
2 steps
*1
Low speed
Not available
1 FUNCTIONS
1.1 Cyclic Transmission
1
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