Appendix 11 Fail-Safe Circuit - Mitsubishi Electric MELSEC Q Series User Manual

APPENDICES
Appendix 11
Fail-Safe Circuit
At power-on/off of the C Controller module, the control output may become inoperable temporarily due to the
difference between the delay time and rising time of the C Controller module power supply and the controlled external
power supply (especially for DC).
For example, if the controlled external power supply is energized in the DC output module and then the C Controller
system power supply is energized, a momentary incorrect output may occur at power-on of the C Controller system by
the DC output module. Therefore, It is necessary to configure a circuit that can be energized by the C Controller
system power supply first.
In addition, a faulty operation may occur in the event of external power supply failure or failure of the C Controller
module main.
Configure circuits outside the C Controller module for components for which machine damage and/or accidents may
occur due to these faulty operations not leading to faulty operations of the entire system, or in view failsafe (emergency
stop circuit, protection circuit, and interlock circuit, etc.).
A circuit example for system design prepared in the above point of view is illustrated in the next page.
A
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