Mitsubishi Q2ACPU User Manual page 3

Before using this product, please read this manual and the relevant manuals carefully and pay full attention
to safety to handle the product correctly.
In this manual, the safety precautions are classified into two levels: "
WARNING
CAUTION
Under some circumstances, failure to observe the precautions given under "
serious consequences.
Make sure that the end users read this manual and then keep the manual in a safe place for future
reference.
[DESIGN PRECAUTIONS]
Create a safety circuit outside the PLC to ensure the whole system will operate safely even if an
external power failure or a PLC failure occurs. Otherwise, incorrect output or malfunction may cause
an accident.
(1) For an emergency stop circuit, protection circuit and interlock circuit that is designed for
incompatible actions such as forward/reverse rotation or for damage prevention such as the
upper/lower limit setting in positioning, any of them must be created outside the PLC.
(2) When the PLC detects the following error conditions, it stops the operation and turn off all the
outputs.
• The overcurrent protection device or overvoltage protection device of the power supply
module is activated.
• The PLC CPU detects an error such as a watchdog timer error by the self-diagnostics
function.
In the case of an error of a part such as an I/O control part that cannot be detected by the PLC
CPU, all the outputs may turn on. In order to make all machines operate safely in such a case,
set up a fail-safe circuit or a specific mechanism outside the PLC. For fail-safe circuit example,
refer to "LOADING AND INSTALLATION" of this manual.
(3) Depending on the failure of the output module's relay or transistor, the output status may remain
ON or OFF incorrectly. For output signals that may lead to a serious accident, create an external
monitoring circuit.
SAFETY PRECAUTIONS
(Read these precautions before using this product.)
Indicates that incorrect handling may cause hazardous conditions,
resulting in death or severe injury.
Indicates that incorrect handling may cause hazardous conditions,
resulting in minor or moderate injury or property damage.
WARNING
A - 1
WARNING" and "
CAUTION" may lead to
CAUTION".