Omron NJ501-1 Series User Manual page 233

No. Abnormal condition
7 Abnormal operation
occurs for the input
points for the same com-
mon (8 or 16 points).
8 The input operation indi-
cators do not light even
though operation is nor-
mal.
Output Units
No. Abnormal condition
1 None of the outputs turn
ON.
2 None of the outputs turn
OFF.
3 A specific output does
not turn ON and the
operation indicator does
not light.
4 A specific output does
not turn ON, but the
operation indicator is lit.
5 A specific output does
not turn OFF, but the
operation indicator is
not lit.
NJ-series CPU Unit Hardware User's Manual (W500)
Cause
1. Loose screws on the common termi-
nal
2. Faulty contact on the terminal block or
connectors
3. Faulty circuits in the Input Unit
4. Faulty CPU Unit
Faulty LEDs or LED circuits
Cause
1. The load power is not supplied.
2. The load power supply voltage is low.
3. Loose screws on the terminal block
4. Faulty contact on the terminal block or
connectors
5. The fuse in the Output Unit has burned
out due to overcurrent, e.g., from a load
short-circuit. (You can confirm the fuse
status on a fuse indicator for some Out-
put Units.
6. Faulty contact on Unit connector
7. Faulty output circuits
8. Load short-circuit protection has oper-
ated. (You can confirm this on an indica-
tor.)
Faulty output circuits
1. The output ON time is too short in the
user program.
2. The output bit is used in more than one
Out instruction in the user program.
3. Faulty output circuits
1. Faulty output device
2. Output wiring is broken.
3. Loose screws on the terminal block
4. Faulty contact on the terminal block or
connectors
5. The relay is faulty for a Relay Output
Unit.
6. Faulty output circuits
1. The output relay is faulty for a Relay
Output Unit.
2. The leakage current or residual volt-
age prevents resetting.
5 Troubleshooting
Correction
Tighten the screws.
Replace the terminal block or
connector.
Replace the Input Unit.
Replace the CPU Unit.
Replace the Input Unit.
Correction
Supply power.
Maintain the power supply volt-
age within the rating.
Tighten the screws.
Replace the terminal block or
connector.
Replace the Unit.
Replace the Output Unit.
Replace the Output Unit.
Check the load.
Check the output wiring.
Replace the Output Unit.
Correct the user program to
make a longer output ON time.
Correct the user program so that
only one Out instruction controls
the output bit.
Replace the Output Unit.
Replace the device.
Check the output wiring.
Tighten the screw.
Replace the terminal block or
connector.
Replace the Output Unit.
Replace the Output Unit.
Replace the Output Unit.
Replace the external load or add
a dummy resistor.
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