7 Inspection and Maintenance
7-2
CJ2 CPU Unit Hardware User’s Manual
7-1 Inspections
Daily or periodic inspections are required in order to maintain the PLC's functions in peak operating
condition.
Although the major components in CJ-series PLCs have an extremely long life time, they can deterio-
rate under improper environmental conditions. Periodic inspections are thus required to ensure that the
required conditions are being kept.
Inspection is recommended at least once every six months to a year, but more frequent inspections will
be necessary in adverse environments.
Take immediate steps to correct the situation if any of the conditions in the following table are not met.
7-1-1 Inspection Points
Periodic Inspection Points
No. Item Inspection Criteria Action
1 Source Power
Supply
Check for voltage fluctua-
tions at the power supply ter-
minals.
The voltage must be within
the allowable voltage fluctua-
tion range.
Use a voltage tester to check the
power supply at the terminals. Take
necessary steps to bring voltage
fluctuations within limits.
2 I/O Power Supply Check for voltage fluctua-
tions at the I/O terminals.
Voltages must be within
specifications for each Unit.
Use a voltage tester to check the
power supply at the terminals. Take
necessary steps to bring voltage
fluctuations within limits.
3 Ambient environ-
ment
Check the ambient tempera-
ture. (Inside the control panel
if the PLC is in a control
panel.)
0 to 55°C Use a thermometer to check the
temperature and ensure that the
ambient temperature remains
within the allowed range of 0 to
55°C.
Check the ambient humidity.
(Inside the control panel if
the PLC is in a control
panel.)
Relative humidity must be
10% to 90% with no conden-
sation.
Use a hygrometer to check the
humidity and ensure that the ambi-
ent humidity remains between 10%
and 90%. Make sure that conden-
sation does not occur due to rapid
changes in temperature.
Check that the PLC is not in
direct sunlight.
Not in direct sunlight Protect the PLC if necessary.
Check for accumulation of
dirt, dust, salt, metal filings,
etc.
No accumulation Clean and protect the PLC if nec-
essary.
Check for water, oil, or chem-
ical sprays hitting the PLC.
No spray on the PLC Clean and protect the PLC if nec-
essary.
Check for corrosive or flam-
mable gases in the area of
the PLC.
No corrosive or flammable
gases
Check by smell or use a sensor.
Check the level of vibration
or shock.
Vibration and shock must be
within specifications.
Install cushioning or shock absorb-
ing equipment if necessary.
Check for noise sources near
the PLC.
No significant noise sources Either separate the PLC and noise
source or protect the PLC.
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