Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 73

3 SPECIFICATIONS
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(2) Control station switch function
By using this function, if the control station (the station for which the common
parameters have been set) goes down, another normal station becomes the sub-
control station to continue the data link.
1) When the control station goes down, the station
No. 2 becomes the sub-control station.
Down
Switch
Control Sub-control
station station
(station (station
No. 1) No. 2)
Network No. 1
Normal Normal
station station
(station (station
No. 6) No. 5)
(a) When switching the control station, whether to continue the cyclic
transmission or not can be selected from sub-control station.
• Common parameter supplementary setting: "Data link by sub-control
station when control station is down." is available. (For more details, refer
to Section 5.4, "Supplementary Settings.")
Selection of function
1 Select
2 Do not select
(b) When the control station is switched, the data link stops temporarily. During
the data link pause, data immediately before the stop is maintained.
(c) During the data link pause, all the stations except the host are treated as
faulty stations.
REMARKS
1) The control station does not switch even if the cyclic transmission of the control
station is stopped with GX Developer (Refer to Section 7.8).
2) Any of the normal stations whose cyclic transmission is stopped with GX
Developer can be a control station.
2) When the sub-control station No. 2 goes down,
the station No. 3 becomes the sub-control station.
Normal
station
(station
No. 3)
Normal
station
(station
No. 4)
Operation during control station switching
Cyclic transmission
MELSEC-Q
Down
Control Sub-control Sub-control
station station
(station (station
No. 1) No. 2)
Network No. 1
Normal Normal
station station
(station (station
No. 6) No. 5)
Transient transmission
: Continued,
Switch
station
(station
No. 3)
Normal
station
(station
No. 4)
: Stopped
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