Cautions on design
• Install a safety circuit outside the PLC so that the entire system conservatively operates even if
an abnormality occurs in the external power supply or a failure occurs in the PLC.
If the safety circuit is installed inside the PLC, malfunction and erroneous output may cause
accidents.
Make sure to construct an emergency stop circuit, protection circuit, interlock circuit to prevent
damage to a machine or instrument outside the PLC.
• When the PLC or FX2N-2LC detects an abnormality such as a watch dog timer error or input
value error by the self-diagnosis circuit, and all outputs turn off. When an abnormality occurs in
the I/O control area which cannot be detected by the CPU in the PLC, output control may be
disabled.
Design external circuits and the structure so that the entire system conservatively operates in
such cases.
• When a failure occurs in a relay, transistor, triac, etc. in the FX2N-2LC or output unit of PLC,
outputs may keep ON or OFF.
For output signals which may lead to severe accidents, design external circuits and the struc-
ture so that the entire system conservatively operates.
Caution on disposal
• When disposing of the unit, treat it as industrial waste.