Link Refresh - Mitsubishi Electric MELSEC iQ-R Series User Manual

Link refresh

Link refresh is a process of transferring data between a link device used for cyclic transmission and a device in a CPU
module. Link refresh is automatically performed at program END processing.
Concept of the link refresh range (number of points)
The area range set under "Link Refresh Settings" in "Basic Settings" and also specified under "Network Range Assignment"
in "Required Settings" is executed by link refresh.
CPU module
Device
(2)
(1)
(1) Range set in "Link Refresh Settings" under "Basic Settings"
(2) Actual link refresh range
(3) Range set under "Network Range Assignment" in "Required Settings"
Shortening the link refresh time
This function reduces the number of the link refresh points to the CPU module, resulting in a shorter link refresh time.
The following methods can be used to reduce the number of the link refresh points.
• Set only the link devices used in the CPU module as the link refresh range in "Link Refresh Setting" under "Basic Settings".
(Page 61 Link Refresh Settings)
• Directly access infrequently used link devices from the program, and remove the corresponding settings from the link
refresh range. (Page 26 Direct access to link devices)
Setting method
The link refresh is assigned under "Link Refresh Settings" in "Basic Settings". ( Page 61 Link Refresh Settings)
Precautions
■Latched devices of the CPU module
If data in latched devices of the CPU module are cleared to zero on a program when the CPU module is turned off and on or
reset, the data may be output without being cleared to zero, depending on the timing of the link scan and link refresh. Execute
the actions listed in the table below to disable the data in the latched devices of the CPU module.
CPU module device
Latch relay (L), file register (R, ZR)
CPU module device within the latch range
*1 For the initial device value setting of the CPU module, refer to the following.
 GX Works3 Operating Manual
1 FUNCTIONS
24
1.1 Cyclic Transmission Function
RJ71LP21-25
Link device
Link refresh
Empty
Link refresh
Empty
Link refresh
How to disable the setting
Use the initial device value of the CPU module to clear the device to zero.
Delete all the latch range settings specified in "Latch Interval Operation Setting" under
"Device Latch Interval Setting" in "Memory/Device Setting" of "CPU Parameter".
(3)
*1