Mitsubishi Electric MELSEC-QS Series Safety Application Manual page 4

[Design Precautions]
When a safety programmable controller detects an error in an external power supply or a failure in
programmable controller main module, it turns off all the outputs.
Create an external circuit to securely stop the power of hazard by turning off the outputs.
Incorrect configuration may result in an accident.
Create short current protection for a safety relay, and a protection circuit such as a fuse, and breaker,
outside a safety programmable controller.
If load current more than the rating or overcurrent due to a short circuit in the load has flowed in the
CC-Link Safety remote I/O module, the module defines it as a fault and turns off all the outputs.
However, if overcurrent flows in the CC-Link Safety remote I/O module for a long time, it may cause
smoke or a fire. To prevent it, create a safety circuit such as a fuse outside the module.
When data/program change, or status control is performed from a PC to a running safety
programmable controller, create an interlock circuit outside the sequence program and safety
programmable controller to ensure that the whole system always operates safely.
For the operations to a safety programmable controller, pay full attention to safety by reading the
relevant manuals carefully, and establishing the operating procedure.
Furthermore, for the online operations performed from a PC to a safety CPU module, the corrective
actions against a communication error due to a cable connection fault, etc. should be predetermined
as a system.
All output signals from a safety CPU module to the CC-Link Safety master modules are prohibited to
use.
These signals can be found in the CC-Link Safety System Master Module User's Manual.
Do not turn ON or OFF these signals by sequence program, since turning ON/OFF these output
signals of the programmable controller system may cause malfunctions and safety operation cannot
be guaranteed.
All output signals from a safety CPU module to the CC-Link IE Field Network master/local modules
(with safety functions) are prohibited to use.
These signals can be found in the MELSEC-QS CC-Link IE Field Network Master/Local Module
User's Manual.
Do not turn ON or OFF these signals by sequence program, since turning ON/OFF these output
signals of the programmable controller system may cause malfunctions and safety operation cannot
be guaranteed.
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