Error Processing and Correction
Section 5-3
Input Units
Symptom
Cause
Remedy
Not all inputs turn ON or in-
dicators are not lit.
(1) Power is not supplied to Input Unit.
(2) Supply voltage is low.
Supply power
Adjust supply voltage to within rated range.
Tighten screws.
(3) Terminal block mounting screws are
loose.
(4) Faulty contact of terminal block con-
nector.
Replace terminal block connector.
Replace Unit.
Not all inputs turn ON (indi-
cator lit).
Input circuit is faulty.
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.
Check input wiring
(2) Input wiring disconnected.
(3) Terminal block screws are loose.
Tighten screws
(4) Faulty terminal block connector con-
tact.
Replace terminal block connector.
(5) Too short ON time of external input.
(6) Faulty input circuit
Adjust input device
Replace Unit.
(7) Input bit number is used for output in-
struction.
Correct program.
Specific bit does not turn
OFF.
(1) Input circuit is faulty.
Replace Unit.
(2) Input bit number is used for output in-
struction.
Correct program.
Input irregularly turns ON/
OFF.
(1) External input voltage is low.
Adjust external input voltage to within rated
range.
(2) Malfunction due to noise.
Protective measures against noise, such
as:
(1) Install surge suppressor.
(2) Install insulation transformer.
(3) Install shielded cable.
(3) Terminal block screws are loose.
Tighten screws
(4) Faulty terminal block connector con-
tact.
Replace terminal block connector.
Error occurs in units of 8
points.
(1) Common terminal screws are loose.
Tighten screws
(2) Faulty terminal block connector con-
tact.
Replace terminal block connector.
(3) Faulty data bus
(4) Faulty CPU
Faulty indicator
Replace Unit.
Replace CPU.
Replace Unit.
Input indicator is not lit in
normal operation.
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OMRON [ OMRON ELECTRONICS LLC ]
