Omron CS1D DUPLEX SYSTEM - 10-2009 Operation Manual page 453

Troubleshooting Racks and Units
Symptom
Cycle time is too long.
I/O Control Unit and I/O Inter-
face Units do not appear on
CX-Programmer I/O table.
Input Units
Symptom
Not all inputs turn ON or indi-
cators are not lit.
Not all inputs turn ON (indica-
tor lit).
Not all inputs turn OFF.
Specific bit does not turn ON. (1) Input device is faulty.
Specific bit does not turn
OFF.
Input irregularly turns
ON/OFF.
Error occurs in units of
8 points or 16 points, i.e., for
the same common.
Input indicator is not lit in nor-
mal operation.
Cause
(1) A CPU Bus Unit that is allocated many
words (e.g., Controller Link Unit) is
mounted to a Long-distance Expansion
Rack.
(2) A Unit is faulty.
This is not an error. These Units are not allo-
cated I/O words and thus are not registered
in the I/O tables.
Cause
(1) Power is not supplied to Input Unit.
(2) Supply voltage is low.
(3) Terminal block mounting screws are
loose.
(4) Faulty contact of terminal block connec-
tor.
Input circuit is faulty. (There is a short at the
load or something else that caused an over-
current to flow.)
Input circuit is faulty.
(2) Input wiring disconnected.
(3) Terminal block screws are loose.
(4) Faulty terminal block connector contact. Replace terminal block connector.
(5) Too short ON time of external input.
(6) Faulty input circuit
(7) Input bit number is used for output
instruction.
(1) Input circuit is faulty.
(2) Input bit number is used for output
instruction.
(1) External input voltage is low or unstable. Adjust external input voltage to within rated
(2) Malfunction due to noise.
(3) Terminal block screws are loose.
(4) Faulty terminal block connector contact. Replace terminal block connector.
(1) Common terminal screws are loose.
(2) Faulty terminal block connector contact. Replace terminal block connector.
(3) Faulty data bus
(4) Faulty CPU
Faulty indicator or indicator circuit.
Remedy
Move the CPU Bus Unit to the CPU Rack.
Gradually remove/replace Units to deter-
mine the Unit that is faulty, including the
Backplane, Power Supply Unit, I/O Units,
I/O Control/Interface Unit, and I/O Connect-
ing Cable.
---
Remedy
Supply power
Adjust supply voltage to within rated range.
Tighten screws.
Replace terminal block connector.
Replace Unit.
Replace Unit.
Replace input devices.
Check input wiring.
Tighten screws.
Adjust input device.
Replace Unit.
Correct program.
Replace Unit.
Correct program.
range.
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.
Tighten screws.
Tighten screws.
Replace Unit.
Replace CPU.
Replace Unit.
Section 10-3
417