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6 TROUBLESHOOTING
6 TROUBLESHOOTING
The following describes the possible causes and the corrective actions for troubles
occurred when using the A1S66ADA.
(1) When it does not read digital output values
Is the voltage and current supplied properly?
Is the conditions for executing the MOV instruction
turned on?
Are the I/O signals correctly specified in the MOV
instruction?
Is the PLC CPU in the "RUN" state?
Is the RUN LED of the PLC CPU flashing or turned
off?
Is there any faulty connections of the analog input
signal wires, such as loose wires or wire breakage?
Measure the digital output value by disconnecting the
cable for the analog input of the A1S66ADA then
applying the test voltage (stabilized power supply or
batteries) to the terminal of the main module.
Is the 24VDC power supply turned on?
(2) When it does not output analog values
Are the D/A conversion value output enable flags
(YnF, Y(n+1)F) for CH1 and CH2 turned "ON"?
Are the I/O signals correctly specified in the MOV
instruction?
Is the PLC CPU in the "RUN" state?
Is the RUN LED of the PLC CPU flashing or turned
off?
Is there any loose wires or wire breakage?
Is the 24VDC power supply turned on?
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Check Item
Check Item
Corrective Action
Measure using a tester to see whether they are being
supplied.
Check for the ON/OFF status by monitoring from the
peripheral device.
Check the sequence program.
Position the RUN key switch of the PLC CPU at
"RUN".
Check the contents by referring to the User's Manual
of the PLC CPU.
Check for the faulty areas of the signal wires by
visual inspection and continuity checking.
Check the grounding method and wiring, as it may be
influenced by the noise from the external wiring, if the
digital output values are normal at the individual
A1S66ADA station.
Check the power supply (external power supply).
Corrective Action
Monitor from the peripheral device to see whether all
the conditions to be ON are satisfied.
Check the sequence program.
Position the RUN key switch of the PLC CPU at
"RUN".
Check the contents by referring to the User's Manual
of the PLC CPU.
Eliminate the faulty area by visual inspection and
continuity checking.
Check the power supply (external power supply).
MELSEC-A
6
6 - 1
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