Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 127

4 SETUP AND PROCEDURES BEFORE STARTING THE OPERATION
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POINT
Data link operation may be executed when IN and IN or OUT and OUT are
connected with an optical fiber cable. Check that IN and OUT are connected
otherwise the loopback function, the network diagnostic function, and some of other
functions do not operate normally.
The wiring status can be checked by either of the following methods.
(1) When checking by halting data link
Conduct a loop test with the network diagnostics of GX Developer. (Refer to
Section 4.8.1.)
(2) When checking without halting data link
Check the status of SW009C to 009F. (Refer to Section 8.2.11.)
MELSEC-Q
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