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8
TROUBLESHOOTING
CHAPTER8 TROUBLESHOOTING
This chapter explains how to check the data link status and error details.
(1) For the master station
(a) Connect GX Developer to identify a faulty part.
Section 8.2 Connecting GX Developer to Master Station for Error Checking
(b) Use the special relay (for link) or special register (for link) of a CPU module to
identify a faulty part.
Type MELSECNET, MELSECNET/B Data Link System Reference Manual
(c) When the master station is faulty, check the error with the ERROR LED.
Section 8.3 Checking Error with LEDs of Link Module on Faulty Station
(2) For Q series local stations
(a) Data of the special relay (for link) and special register (for link) of a local module
are refreshed into CPU module devices.
The faulty part can be checked by using the refreshed devices.
Appendix 1 List of Special Relays (for Link)
Appendix 2 List of Special Registers (for Link)
Note that the network diagnostics of GX Developer is not available for Q series
local stations. Check the fault by the above method.
(b) When a Q series local station is faulty, check the error with the ERROR LED that
is lit.
Section 8.3 Checking Error with LEDs of Link Module on Faulty Station
(c) Check for proper cable connection.( Section 5.4 Wiring)
1) In the MELSECNET data link system, are the slave stations connected in order
of station No. starting from the master station (01 02 n (n 64)) in the
forward loop direction?
2) Isn't any station No. skipped in the setting?
3) Isn't any station No. duplicated in the same tier?
(d) Check the program for refresh and for receiving LRDP/LWTP instruction.
Section 8.4 Checking the Program for Refresh