Safety Instructions - Mitsubishi Electric MELSEC-Q Series User Manual

When using Mitsubishi equipment, thoroughly read this manual and the associated manuals introduced in
this manual. Also pay careful attention to safety and handle the module properly.
These SAFETY PRECAUTIONS classify the safety precautions into two categories: "DANGER" and
"CAUTION".
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DANGER
CAUTION
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Note that the CAUTION level may lead to a serious consequence according to the circumstances.
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Always follow the instructions of both levels because they are important to personal safety.
Please save this manual to make it accessible when required and always forward it to the end user.
[Design Precautions]
• Install a safety circuit external to the PLC that keeps the entire system safe even when there are
problems with the external power supply or the PLC module. Otherwise, trouble could result
from erroneous output or erroneous operation.
(1) Outside the PLC, construct mechanical damage preventing interlock circuits such as
emergency stop, protective circuits, positioning upper and lower limits switches and
interlocking forward/reverse operations.
(2) When the PLC 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 stop calculation and hold or turn off all output
according to the parameter setting.
(a) The power supply module has over current protection equipment and over voltage
protection equipment.
(b) The PLC CPUs self-diagnostic functions, such as the watchdog timer error, detect
problems.
In addition, all output will be turned on when there are problems that the PLC CPU cannot
detect, such as in the I/O controller. Build a fail safe circuit exterior to the PLC that will make
sure the equipment operates safely at such times. Refer to " LOADING AND
INSTALLATION" in Basic Model QCPU (Q Mode) User's Manual (Hardware Design,
Maintenance and Inspection) for example fail safe circuits.
(3) Output could be left on or off when there is trouble in the outputs module relay or transistor.
So build an external monitoring circuit that will monitor any single outputs that could cause
serious trouble.
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• SAFETY INSTRUCTIONS •
(Always read these instructions before using this equipment.)
Indicates that incorrect handling may cause hazardous conditions,
resulting in death or severe injury.
Indicates that incorrect handling may cause hazardous conditions,
resulting in medium or slight personal injury or physical damage.
DANGER
!
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