Troubleshooting Of Master Module; Qj51Aw12D2 - Mitsubishi Electric MELSEC-Q Series User Manual

9.3

Troubleshooting of Master Module

This section describes the troubleshooting of the master module.
9.3.1

QJ51AW12D2

(1) The M ERR.LED on the master module is 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.
(2) The LINK LED on the master module does not flash.
Item
Check that the LINK LED is off.
(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.
If the M ERR.LED does not turn off after the master module is powered on, a
hardware failure may have occurred.
Please consult your local Mitsubishi representative.
A malfunction has been detected in the master module hardware.
Reset the master module.
If the error occurs again, the module may be in failure. Please consult your local
Mitsubishi representative.
Adjust the power supply voltage of the 24VDC external power supply 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.
CHAPTER 9 TROUBLESHOOTING
Action
Action
Action
Action
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