Safety Precautions - Mitsubishi Electric MELSEC-L SSCNETIII/H User 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.
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) Emergency stop circuits, protection circuits, and protective interlock circuits for conflicting
operations (such as forward/reverse rotations or upper/lower limit positioning) must be configured
external to the programmable controller.
(2) When the programmable controller detects an abnormal condition, it stops the operation and all
outputs are:
• Turned off if the overcurrent or overvoltage protection of the power supply module is activated.
• Held or turned off according to the parameter setting if the self-diagnostic function of the head
module detects an error such as a watchdog timer error.
Also, all outputs may be turned on if an error occurs in a part, such as an I/O control part, where
the head 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 Page 134, Appendix 9.
(3) Outputs may remain on or off due to a failure of a component such as a relay and transistor in an
output circuit. 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
WARNING" and " CAUTION".
CAUTION" may lead to
1