Mitsubishi Electric L26CPU-BT User Manual page 160

(1) Setting method
The following shows how to make settings.
(a) Set station No.0 for the master station, and any of station 1 to 64 for the standby
master station.
(b) Configure the same system (the same programmable controller CPU, I/O modules,
and/or intelligent function modules) for the master and standby master stations.
(c) Select "Master Station (Duplex Function)" for "Type" in the network parameter
setting of GX Works2.
(d) Set other network parameter items.
(e) Write the same parameters and programs to the master and standby master
stations.
(2) Precautions when starting data link by the standby master station
(a) Parameters and program set in the master station and standby master station
Set the same parameters and program in the master station and standby master station. If not, the operation is
not guaranteed.
(b) Line test
When the data link start function by a standby master station is used, a line test cannot be executed using the
mode setting. Use a programming tool to execute a line test. (
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Page 378, Section 15.4.2 (1))