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Safety Precautions - Mitsubishi Electric Artisan MELSEC-Q Series Manual

General-purpose programmable controllers, large/small
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● When replacing A (Large Type)/AnS (Small Type) Series with Q Series ●
Before using products introduced in this publication, please read this Transition
Examples and relevant manuals carefully and pay full attention to safety to handle
the product correctly.
In this publication, the safety precautions are classified into two levels:
WARNING" and "
Under some circumstances, failure to observe the precautions given under "
to serious consequences.
Observe the precautions of both levels because they are important for personal and system safety.
Make sure that the end users read this publication and keep it in a safe place for future reference.
● Configure safety circuits external to the programmable controller to ensure that the entire system operates
safely even when a fault occurs in the external power supply or the programmable controller. Failure to do
so may result in an accident due to an incorrect output or malfunction.
(1) Configure external safety circuits, such as an emergency stop circuit, protection circuit, and protective
interlock circuit for forward/reverse operation or upper/lower limit positioning.
(2) The programmable controller stops its operation upon detection of the following status, and the output
status of the system will be as shown below.
Overcurrent or overvoltage protection of
the power supply module is activated.
The CPU module detects an error such as
a watchdog timer error by the self-diagnostic
All outputs may turn on when an error occurs in the part, such as I/O control part, where the CPU module
cannot detect any error. To ensure safety operation in such a case, provide a safety mechanism or a
fail-safe circuit external to the programmable controller. For a fail-safe circuit example, refer to LOADING
AND INSTALLATION in the QCPU User's Manual (Hardware Design, Maintenance and Inspection).
(3) Outputs may remain on or off due to a failure of an output module relay or transistor. Configure an
external circuit for monitoring output signals that could cause a serious accident.
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Safety Precautions

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.
Design Precautions
All outputs are held or turned
off according to the parameter
Q Series Module
All out puts are turned off.
CAUTION" may lead
A/AnS Series module
All out puts are turned off.
All out puts are turned off.



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