Safety Precautions - Mitsubishi Electric MELSEC Q Series Handbook

Before using products introduced in this publication, please read relevant manuals and replacement
handbooks 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 "
WARNING
CAUTION
Under some circumstances, failure to observe the precautions given under "
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.
[Design Precautions]
● 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 function.
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 General Safety Requirements 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.

SAFETY PRECAUTIONS

(Read these precautions before using this product.)
CAUTION".
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
Q series module
All outputs are turned off
All outputs are held or turned off
according to the parameter setting.
CAUTION" may lead to
A/AnS series module
All outputs are turned off
All outputs are turned off
A
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