Safety Precautions - Mitsubishi Electric MELSEC-A/QnA Series Handbook

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.
Observe the precautions of both levels because they are important for personal and system safety.
Make sure that the end users read this manual and then keep the manual 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) When the programmable controller detects the following problems,
it will stop calculation and turn off all output in the case of (a).
In the case of (b), it will hold or turn off all output according to the parameter setting.
Note that the AnS series module will turn off the output in either of cases (a) and (b).
(a) The power supply module has over current
protection equipment and over voltage
protection equipment.
(b) The CPU module self-diagnosis functions, such
as the watchdog timer error, detect problems.
Also, all outputs may be turned on if an error occurs in a part, such as an 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.

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
Hold or turn off all output
according to the parameter
setting.
WARNING" and "
CAUTION" may lead to
Q series module
Output OFF
CAUTION".
A series module
Output OFF
Output OFF
A
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