Mitsubishi Electric MELSEC iQ-R Series User Manual page 122

Problem Check item
A station A4-1
cannot
perform data
link
occasionally.
A4-2
A4-3
A4-4
A4-5
A4-6
4 TROUBLESHOOTING
120
4.5 Troubleshooting by Symptom
Description
Cable or other Are there no disconnection, short
parts circuit, incorrect wiring, poor
connection, and coexistence of
different cables? Do a
transmission distance, station-to-
station distance, transmission
cable, and FG terminal grounding
meet the specifications?
Are terminating resistors
connected?
Power supply (for Is the power on, and is the applied
communications) voltage within the specified
range?
Noise Is the transmission cable free from
noise?
Start-up Has the faulty station started with
the correct procedure?
Failure of a slave Do slave stations normally
station operate?
Standby master Is the standby master station
station controlling the data link?
Check method
Check cables connected to the faulty
station.
When faulty stations occur sequentially
to one end on the transmission path,
check cables connected to faulty
stations close to the master station.
(Multiple stations)
Check if terminating resistors are
connected to the both ends in the CC-
Link system.
Check if a station with built-in
terminating resistor is connected other
than at both ends in the CC-Link
system.
Check power supplied to the faulty
station.
Check if the transmission cable is
away from the power cable.
Check if the FG terminal is grounded
separated from the GND terminal of
the power system.
Reduce the transmission speed and
check if the frequency of occurrence of
noise is reduced.
Check if the faulty station normally
starts with a different procedure.
Replace modules on the faulty station
and check if the station normally
operates.
Check if the standby master station is
not set as a station controlling the data
link by the CC-Link diagnostics of the
master station.
Action
Correct the wiring.
Connect terminating resistors to
the both ends in the CC-Link
system.
Apply the voltage within the
specified range.
Keep the transmission cable away
from the power cable.
Ground the terminals separately.
• Take measures to reduce noise.
• Reduce the transmission speed.
Start the faulty station by following
the procedure described in the
manual for the station.
Repair or replace the module on
the faulty station.
Restart the system so that the
master station will control the data
link.