5 Troubleshooting
5-96
NJ-series CPU Unit Hardware User’s Manual (W500)
6 A specific output does
not turn OFF and the
operation indicator is lit.
1. The output bit is used in more than one
Out instruction in the user program.
Correct the user program so that
only one Out instruction controls
the output bit.
2. Faulty output circuits Replace the Output Unit.
7 The output turns ON
and OFF irregularly.
1. The load power supply voltage is low
or unstable.
Maintain the load power supply
voltage within the rating.
2. The output bit is used in more than one
Out instruction in the user program.
Correct the user program so that
only one Out instruction controls
the output bit.
3. Malfunction caused by noise Implement noise countermea-
sures.
• Attach a surge suppressor.
• Install an isolation transformer.
• Use a shielded cable between
the Output Unit and the load.
4. Loose terminal block Tighten the screws.
5. Faulty contact on the terminal block or
connectors
Replace the terminal block or
connector.
8 Abnormal operation
occurs for the output
points for the same
common (8 or 16
points).
1. Loose screws on the common terminal Tighten the screws.
2. Faulty contact on the terminal block or
connectors
Replace the terminal block or
connector.
3. The fuse in the Output Unit has burned
out due to overcurrent, e.g., from a load
short-circuit.
Replace the Output Unit.
4. Faulty circuits in the Output Unit Replace the Output Unit.
5. Faulty CPU Unit Replace the CPU Unit.
6. Load short-circuit protection has oper-
ated. (You can confirm this on an indica-
tor.)
Check the load.
Check the output wiring.
9 The output operation
indicators do not light
even though operation
is normal.
Faulty LEDs or LED circuits Replace the Unit.
10 The ERR indicator (load
short-circuit alarm) is lit
and the output is OFF.
The load is short-circuited externally or
disconnected.
Refer to A-4-1 Load Short-circuit
Protection and Line Disconnec-
tion Detection for CJ1W-OD202.
No. Abnormal condition Cause Correction
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