Output Wiring Procedures; Damage To The Product Or Electric Shock - Mitsubishi FX3U SERIES User Manual

FX Series Programmable Controllers
3U
User's Manual - Hardware Edition

12. Output Wiring Procedures

DESIGN PRECAUTIONS
• Make sure to have the following safety circuits outside of the PLC to ensure safe system operation even during
external power supply problems or PLC failure.
Otherwise, malfunctions may cause serious accidents.
1) Most importantly, have the following: an emergency stop circuit, a protection circuit, an interlock circuit for
opposite movements (such as normal vs. reverse rotation), and an interlock circuit (to prevent damage to the
equipment at the upper and lower positioning limits).
2) Note that when the PLC CPU detects an error, such as a watchdog timer error, during self-diagnosis, all
outputs are turned off. Also, when an error that cannot be detected by the PLC CPU occurs in an input/output
control block, output control may be disabled.
External circuits and mechanisms should be designed to ensure safe machinery operation in such a case.
3) Note that the output current of the 24V DC service power supply varies depending on the model and the
absence/presence of extension blocks. If an overload occurs, the voltage automatically drops, inputs in the
PLC are disabled, and all outputs are turned off.
External circuits and mechanisms should be designed to ensure safe machinery operation in such a case.
4) Note that when an error occurs in a relay, triac or transistor output device, the output could be held either on
or off.
For output signals that may lead to serious accidents, external circuits and mechanisms should be designed
to ensure safe machinery operation in such a case.
DESIGN PRECAUTIONS
• Do not bundle the control line together with or lay it close to the main circuit or power line. As a guideline, lay the
control line at least 100mm (3.94") or more away from the main circuit or power line.
Noise may cause malfunctions.
• Install module so that excessive force will not be applied to peripheral device connectors.
Failure to do so may result in wire damage/breakage or PLC failure.
WIRING PRECAUTIONS
• Connect the AC power supply to the dedicated terminals specified in this manual.
If an AC power supply is connected to a DC input/output terminal or DC power supply terminal, the PLC will burn
out.
• Cut off all phases of the power supply externally before installation or wiring work in order to avoid damage to the
product or electric shock.
• Make sure to attach the terminal cover, offered as an accessory, before turning on the power or initiating
operation after installation or wiring work.
Failure to do so may cause electric shock.
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