Omron SYSMAC CS Series Operation Manual page 614

Troubleshooting Racks and Units
Symptom
Output of a specific bit num-
ber does not turn OFF (indi-
cator lit).
Output irregularly turns
ON/OFF.
Error occurs in units of
8 points or 16 points, i.e., for
the same common.
Output indicator is not lit
(operation is normal).
576
Cause
(1) Bit status controlled by multiple instruc-
tions.
(2) Faulty output circuit.
(1) Low or unstable load voltage.
(2) Bit status controlled by multiple instruc-
tions.
(3) Malfunction due to noise.
(4) Terminal block screws are loose.
(5) Faulty terminal block connector contact. Replace terminal block connector.
(1) Loose common terminal screw.
(2) Faulty terminal block connector contact. Replace terminal block connector.
(3) An overcurrent (possibly caused by a
short at the load) resulted in a blown
fuse in the Output Unit.
(4) Faulty data bus.
(5) Faulty CPU.
Faulty indicator.
Remedy
Correct program.
Replace Unit.
Adjust load voltage to within rated range
Correct program so that each output bit is
controlled by only one instruction.
Protective measures against noise:
(1) Install surge suppressor.
(2) Install insulation transformer.
(3) Use shielded cables between the Output
Unit and the loads.
Tighten screws.
Tighten screws.
Replace fuse or Unit.
Replace Unit.
Replace CPU.
Replace Unit.
Section 11-3