Safety Precautions - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

Before using this product, please read this manual and the relevant manuals carefully and pay full
attention to safety to handle the product correctly.
The instructions given in this manual are concerned with this product. For the safety instructions of the
programmable controller system, please read the CPU module user's manual.
In this manual, the safety precautions are classified into to levels: "
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]
• For operating status of each communication failure, refer to this manual. Incorrect output or
malfunction due to a communication failure may result in an accident.
• If a coaxial cable is disconnected, this may destabilize the line, and a network communication
error may occur in multiple stations. Provide an interlock circuit in the sequence program so that
the system will operate safely even if the above error occurs. Failure to do so may result in an
accident due to incorrect output or malfunction.
• When changing data of the running programmable controller from a peripheral connected to the
CPU module or from a personal computer connected to an intelligent function module or special
function module, configure an interlock circuit in the sequence program to ensure that the entire
system will always operate safely.
For program modification and operating status change, read relevant manuals carefully and
ensure the safety before operation.
Especially, in the case of a control from an external device to a remote programmable controller,
immediate action cannot be taken for a problem on the programmable controller due to a
communication failure.
To prevent this, configure an interlock circuit in the sequence program, and determine corrective
actions to be taken between the external device and CPU module in case of a communication
failure.
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• SAFETY PRECAUTIONS •
(Read these precautions before using this product.)
WARNING
!
WARNING" and "
! !
CAUTION" may lead to
!
CAUTION".
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