Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 137

4 SETUP AND PROCEDURES BEFORE STARTING THE OPERATION
MELSEC-Q
REMARKS
Before conducting the station-to-station test when three or more stations are
connected by the coaxial/twisted bus system, any stations that are not tested must
be switched to offline or powered off.
Station to Station to Offline or
execute test be tested powered off
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