Mitsubishi Electric MELSEC Q Series User Manual page 252

(b) Direct access/buffer memory access
Link refresh time can be reduced by excluding infrequently used link devices in the host station from the link
refresh range by means of direct access or buffer memory access.
C Controller
module
User program
Processing that always requires
writing (frequently-used link device)
Processing that performs writing
as necessary (less
frequently-used link device)
Processing that always requires
read-out (frequently-used link
device)
Processing that performs read-out
as necessary (less frequently-used
link device)
(2) Reducing the link scan time
For MELSECNET/H, link refresh and link scan data (LB/LW) can be reduced by assigning data not required to be
high-speed during normal cyclic transmission (LB/LW) to the extension area (2000
low-speed cyclic transmission.
Station
No.1
Station
No.2
Station
No.3
1FFF
250
C Controller
module
Internal user
Access to device
the internal
user device
Access to
the internal
user device
C Controller module
Internal user
device
0
H
Link refresh
H
Low speed link refresh
Network module
Network Range Assignment
(Network Configuration Settings)
parameter
Link refresh
Direct access
Link refresh
Direct access
MELSECNET/H module
network range
assignment parameter
0
H
Station
No.1
Normal cyclic
Station
No.2
transmission range
Station
No.3
2000
H
Station
No.1
Low speed cyclic
Station
No.2 transmission range
Station
No.3
3FFF
H
Send range to the
other station
Receive range from
other stations
to 3FFF ) and performing
H H