Omron CJ - 08-2008 - Page 574

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Troubleshooting Racks and Units Section 11-3
Input Units
Symptom Cause Remedy
Not all inputs turn ON or indi-
cators are not lit.
(1) Power is not supplied to Input Unit. Supply power
(2) Supply voltage is low. Adjust supply voltage to within rated range.
(3) Terminal block mounting screws are
loose.
Tighten screws.
(4) Faulty contact of terminal block connec-
tor.
Replace terminal block connector.
Not all inputs turn ON (indica-
tor lit).
Input circuit is faulty. (There is a short at the
load or something else that caused an over-
current to flow.)
Replace Unit.
Not all inputs turn OFF. Input circuit is faulty. Replace Unit.
Specific bit does not turn ON. (1) Input device is faulty. Replace input devices.
(2) Input wiring disconnected. Check input wiring
(3) Terminal block screws are loose. Tighten screws
(4) Faulty terminal block connector contact. Replace terminal block connector.
(5) Too short ON time of external input. Adjust input device
(6) Faulty input circuit Replace Unit.
(7) Input bit number is used for output
instruction.
Correct program.
Specific bit does not turn
OFF.
(1) Input circuit is faulty. Replace Unit.
(2) Input bit number is used for output
instruction.
Correct program.
Input irregularly turns ON/
OFF.
(1) External input voltage is low or unstable. Adjust external input voltage to within rated
range.
(2) Malfunction due to noise. Take protective measures against noise,
such as:
(1) Increase input response time (PLC
Setup)
(2) Install surge suppressor.
(3) Install insulation transformer.
(4) Install shielded cables between the Input
Unit and the loads.
(3) Terminal block screws are loose. Tighten screws
(4) Faulty terminal block connector contact. Replace terminal block connector.
Error occurs in units of
8 points or 16 points, i.e., for
the same common.
(1) Common terminal screws are loose. Tighten screws
(2) Faulty terminal block connector contact. Replace terminal block connector.
(3) Faulty data bus Replace Unit.
(4) Faulty CPU Replace CPU.
Input indicator is not lit in nor-
mal operation.
Faulty indicator or indicator circuit. Replace Unit.