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MELSEC-Q
7 APPLICATION FUNCTIONS
3) Execution using the sequence program (Not allowed for the Basic
model QCPU and safety CPU)
The data receiving between the CPU module and network modules
(link refreshing) is not stopped or restarted by stopping/restarting the
cyclic transmission.
Thus, it is necessary to stop/restart link refreshing by the sequence
program using the CPU module's special relay (SM).
Link refreshing is stopped or restarted by Host data link status
(SB0049) as shown in the following program.
4) Whether or not the restart operation is possible as determined by the
stop operation method
The priority order of startup and stop is as follows:
Link startup < Link stop < Forced link startup.
Type of restart
operation
Target
station
Status of target station
Link startup Forced link startup
Host
Designated
station
All stations Host
Specified
station
All stations
Stop link by specifying host
Stop link by specifying specified station
Stop link by specifying all the stations
: Startup possible : Startup not possible
POINT
Link start cannot be done even if the link start operation is performed to an offline-
mode station (disconnected from the network).
No error will be detected, in this case, because no response is returned from the
target station.
SB0049
SM256
Host data link status
Off: Being executed
On: Stopped
Refresh between the network modules and the CPU
Off: Refreshes
On: Does not refresh
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