Omron CP1H-CPU - 05-2006, Operation Manual

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Troubleshooting Unit Errors
Section 9-4
9-4 Troubleshooting Unit Errors
CPU Unit
Special I/O Units
Refer to the operation manual for the Special I/O Unit to troubleshoot any
other errors.
Inputs
Symptom Cause Remedy
POWER indicator is not lit. PCB short-circuited or damaged. Replace Unit.
Correct program.
Replace Unit.
RUN indicator is not lit. (1) Error in program (fatal error)
(2) Power line is faulty.
Replace Unit.
RUN indicator on the CPU Unit is lit. Internal circuitry in the Unit is faulty. Replace Unit.
Special I/O Unit or CPU Bus Unit does
not operate or malfunctions. (1) The I/O Connecting Cable is faulty.
(2) The I/O bus is faulty.
Replace Unit.
Bits do not operate past a certain point.
Error occurs in units of 8 or 16 points.
I/O bit turns ON.
All bits in one Unit do not turn ON.
Symptom Cause Remedy
The ERH and RUN
indicators on the Spe-
cial I/O Unit are lit. I/O refreshing is not being performed for the
Unit from the CPU Unit (CPU Unit monitoring
error). Enable cyclic refreshing for the Unit in the PLC
Setup, or make sure that the Unit is refreshed
from the program using IORF at least once
every 11 s.
Symptom Cause Remedy
Not all inputs turn ON or indi-
cators are not lit. (1) External power is not supplied for the
input.
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 even
though the indicator is 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.