6 Troubleshooting
6-30
CJ2 CPU Unit Hardware User’s Manual
z Special I/O Units
Refer to the Operation Manual for the Special I/O Unit to troubleshoot any other errors.
7 Output irregularly turns ON/OFF. Low or unstable load voltage. Adjust load voltage to within
rated range.
Bit status controlled by multiple
instructions.
Correct program so that each
output bit is controlled by only
one instruction.
Malfunction due to noise. Protective measures against
noise:
• Install surge suppressor.
• Install insulation transformer.
• Use shielded cables between
the Output Unit and the loads.
Terminal block screws are loose. Tighten screws.
Faulty terminal block connector
contact.
Replace terminal block connec-
tor.
8 Error occurs in units of 8 points
or 16 points, i.e., for the same
common.
Loose common terminal screw. Tighten screws.
Faulty terminal block connector
contact.
Replace terminal block connec-
tor.
An overcurrent (possibly caused
by a short at the load) resulted in
a blown fuse in the Output Unit.
Replace fuse.
Faulty data bus. Replace Unit.
Faulty CPU. Replace CPU.
9 Output indicator is not lit (opera-
tion is normal).
Faulty indicator. Replace Unit.
10 ERR indicator (load short-circuit
alarm) lights and outputs turn
OFF.
An external short-circuit or dis-
connection occurred.
Refer to A-6-1 Load Short-circuit
Protection and Line Disconnec-
tion Detection for CJ1W-OD202.
No. Symptom Cause Remedy
1 The ERH and RUN indicators on
the Special I/O Unit are lit.
Special I/O refreshing is not
being performed for the Unit from
the CPU Unit (CPU Unit monitor-
ing error).
Change the bit corresponding to
the unit number to 0 to enable
cyclic refreshing, or make sure
that the Unit is refreshed from
the program using IORF or
FIORF at least once every 11 s.
No. Symptom Cause Remedy
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