Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 74

3 SPECIFICATIONS
1
2
1) When the control station is down, the station
No. 2 becomes the sub-control station.
Down
Control
station
(station
No. 1)
Normal
station
(station
No. 6)
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(3) Control station return control function
The network stop time can be eliminated by correcting the errors that caused the
control station to go down and making it return to the network as a normal station.
How the control station returns to the network can be selected by the network
settings.
For details of the network setting, refer to Section 5.5, "Control Station Return
Setting."
For the control station return control function in the redundant system, refer to
Section 7.10.6.
Selection of function
Return as the control station The control station returns as the control station of the network.
The control station returns to the network again as a normal station, making the operating
Return as a normal station sub-control station the new control station of the network. It can become the control station
again only by returning to the network when all other stations have gone down.
Sub-control Normal
station station
(station (station
No. 2) No. 3)
Network No. 1
Normal Normal
station station
(station (station
No. 5) No. 4)
REMARKS
• When "Return as the control station" is selected, the network stop time
becomes longer because the baton pass is stopped, but the common
parameters can be changed only by resetting the CPU of the control station.
• If "Return as a normal station" is selected, the network does not stop because
the control station returns to the network without stopping the baton pass.
However, it is necessary to reset the CPUs of all the stations after changing the
common parameters of the control station while the network is operating. If only
the CPU of the control station is reset, a parameter mismatch error is detected
in the control station and it is disconnected from the network.
Control station after returning
2) The network does not stop since the control station
returns to the network as a normal station.
Return
Control
station
(station
No. 1)
Return
Network No. 1
Normal
station
(station
No. 6)
MELSEC-Q
Sub-control Normal
station station
(station (station
No. 2) No. 3)
Normal Normal
station station
(station (station
No. 5) No. 4)
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