Mitsubishi Electric MELSEC iQ-R Series User Manual page 46

Precautions
When the RJ71LP21-25 fails, loopback may not be performed depending on what kind of failure occurs.
In such a case, data link may be stopped. To identify the RJ71LP21-25 with a failure, perform either of the following.
• Check the LED indication of all network modules for abnormal stations. (Page 90 Checking with LED)
• Turn off the power of all stations, then turn on the power of stations in order, starting from the control station. While doing
this, check up to which station on the network loopback is normally performed. Check whether the control station and a
returned normal station are displayed on a loopback station in the link information of the MELSECNET diagnostics (own
station information).
Replace the RJ71LP21-25 where a failure was detected with a new one and check that data link has returned to normal
status.
1 FUNCTIONS
44
1.3 RAS