Mitsubishi L26CPU-BT, User Manual

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8 FUNCTIONS
(3) Precautions on using the standby master function
(a) Only one standby master station exists in a single data link system.
(b) If an error is detected at the master station in the initial status (before
parameter communication starts), switching to the standby master station
will not be executed.
(c) When the master station becomes faulty, the data link control will
automatically be transferred to the standby master station, but the refresh
instruction of the cyclic data will not be issued. Specify the cyclic data refresh
using the program. Once specified, the information prior to the error
detection at the master station will be output to each station.
(d) When the data link is being controlled by the standby master station, the
master station's parameters cannot be updated.
(e) An error (error code: B39A
H
) occurs at the standby master station if there is
a difference between the station number setting of the network parameter
“Station No." of the standby master station and the station number setting of
the network parameter “Standby Master Station No." of the master station.
If an error has occurred, change the “Standby Master Station No." of the
master station or the “Station No." of the standby master station, and then
reset the programmable controller CPU of the standby master station.
(f) If the terminal block of the master station is removed and then replaced in its
original position without turning the power off when the master station is
controlling the data link, both the master and standby master stations
operate as master stations. An error occurs since the data link control has
been transferred to the standby master station ("ERR." LED turns on).
(g) When the master station becomes faulty and the data link control is
transferred to the standby master station, the "ERR." LED of the standby
master station flashes. (This is because the station number of the standby
master station will change from the one set with a parameter to "0" and the
standby station becomes nonexistent. Data link itself is performed normally.)
To avoid this situation, set the standby master station to be an error invalid
station.
(h) The number and range of devices that will be saved by the program among
the data sent from (the station operating as) the master station to (the station
operating as) the standby station may differ according to the system used.