Mitsubishi FX3U-20SSC-H User Manual page 3

Before installing, operating, maintenance or inspecting this product, thoroughly read and understand this
manual and the associated manuals. Also pay careful attention to handle the module properly and safety.
This manual classifies the safety precautions into two categories:
Depending on circumstances, procedures indicated by
In any case, it is important to follow the directions for usage.
Store this manual in a safe place so that you can take it out and read it whenever necessary. Always forward
it to the end user.
1. DESIGN PRECAUTIONS
• Provide a safety circuit on the outside of the PLC so that the whole system operates to ensure the safety even when
external power supply trouble or PLC failure occurs.
Otherwise, malfunctions or output failures may result in an accident.
1) An emergency stop circuit, a protection circuit, an interlock circuit for opposite movements, such as normal and
reverse rotations, and an interlock circuit for preventing damage to the machine at the upper and lower
positioning limits should be configured on the outside of the PLC.
2) When the PLC CPU detects an error, such as a watch dog timer error, during self-diagnosis, all outputs are
turned off. When an error that cannot be detected by the PLC CPU occurs in an input/output control block,
output control may be disabled.
Design external circuits and mechanisms to ensure safe operations of the machine in such a case.
3) When some sort of error occurs in a relay, triac or transistor of the output unit, output may be kept on or off.
For output signals that may lead to serious accidents, design external circuits and mechanisms to ensure safe
operations of the machine in such cases.
• At forward/reverse rotation limits wiring, make sure to wire in negative logic and use NC contact. Setting in positive
logic and using NC-contact can cause serious accidents.
• Observe the following items. Failure to do so may cause incorrect data-writing by noise to PLCs and result the PLC
failure, machine damage or an accident.
1) Do not lay close or bundle with the main circuit line, high-voltage line, or load line.
Noise and Surge induction interfere with the system operation.
Keep a safe distance of least 100 mm (3.94") from the above lines during wiring.
2) Ground the shield wire or shield of a shielded cable at one point on the PLC. However, do not ground at the
same point as high voltage lines.
• Install in a manner which prevents excessive force from being applied to the built-in connectors dedicated to
programming, power connectors and I/O connectors.
Failure to do so may result in wire breakage or failure of the PLC.
2. INSTALLATION PRECAUTIONS
• Make sure to cut off all phases of the power supply externally before starting the installation or wiring work.
Failure to do so may cause electric shock.
Safety Precautions
(Read these precautions before using.)
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.
(1)
and
may also be linked to serious results.
.
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