Mitsubishi Electric MELSEC-Q Series User Manual page 285

Problem Check item
Power supply (for
B2-1
communications)
Cable or other
B2-2
parts
Data link
cannot be
performed in
the entire
system
occasionally.
B2-3 Noise
Failure of a slave
B2-4
station
Description
Isn't a voltage low?
Are cables and connectors
securely connected and do
they meet specifications?
Is the transmission cable free
from noise?
Do slave stations normally
operate?
CHAPTER 11 TROUBLESHOOTING
Check method
Check power supplied to the
faulty station.
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.
Check if the transmission cable is
away from the power cable.
Check if the FG terminal is
grounded separately from the
GND terminal of the power
system.
Reduce the transmission speed
and check if the frequency of
occurrence of noise is reduced.
Replace modules on the faulty
station and check for operation.
Corrective action
Apply the voltage
within the specified
range.
11
Correct the wiring.
Keep the transmission
cable away from the
power cable.
(Keep a distance of
100mm or more is
recommended.)
Ground the terminals
separately.
Take noise reduction
measures.
Reduce the
transmission speed.
Repair or replace the
module on the faulty
station.
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