Mitsubishi Electric MELSEC-Q Series User Manual page 67

(3) The ALM LED on the master module is flashing at 0.2 second intervals.
Item
Check the power supply voltage of
the 24VDC external power supply.
Check that the power cables (24V,
0V) are not short-circuited.
Check the wiring of the terminal
blocks.
(4) The ALM LED on the master module is flashing at 1 second intervals.
Item
Check that the transmission cables
(between D and G, D and 24V) are
not short-circuited.
Check the wiring of the terminal
blocks.
(5) The ALM LED on the master module is on.
Item
Check that the transmission cables
(D G) are not disconnected.
Check the wiring of the terminal
blocks.
Execute the automatic address
detection function.
Check the existence of the slave
module.
(6) The RUN LED on the master module does not turn on.
Item
Check that the supply power to the
programmable controller system is
within the specifications.
Check that a hardware failure or a
watchdog timer error has not
occurred.
Adjust the power supply voltage of the 24VDC external power supply connected to
the master module to be within the rated value (21.6 to 27.6VDC).
• Check that the power cables (24V, 0V) are not disconnected or short-circuited.
• When crimping the link connector, check that the pin assignment is correct.
• Check that the 24VDC external power supply is properly connected to the terminal
block of the master module or the slave module.
• Check that there is no short-circuit or incorrect wiring and screws have been
tightened sufficiently.
• Check that the transmission cables (between D and G, D and 24V) are not short-
circuited.
• When crimping the link connector, check that the pin assignment is correct.
Check that the transmission cables (D, G) are not short-circuited and there is no
incorrect wiring in the terminal block wiring of the master module and the slave
module.
• Check that the entire transmission cables (D, G) are free from disconnection.
• Check that the cables have been crimped with proper pin assignment using link
connectors appropriate to the wire diameter.
• Check that the transmission cables (D, G) and power cables (24V, 0V) are
properly connected to the terminal block of the master module.
• Check that there is no incorrect wiring and screws have been tightened
sufficiently.
When creating a new system, adding or removing a slave module, or changing the
address of the slave module, execute the automatic address detection function.
After executing the automatic address detection function, check that the number of
slave modules and the address are consistent with those of the actual system.
If the LINK LED of the slave module is not flashing, check that there is no
disconnection, short-circuit, incorrect wiring, or poor contact in the transmission
cables around the slave module.
If the RUN LED does not turn on after powering on the master module, hardware
failure may have occurred.
Please consult your local Mitsubishi representative.
CHAPTER 9 TROUBLESHOOTING
Action
Action
Action
Action
9
65