Mitsubishi FX3U-20SSC-H User Manual page 3

Before installation, operation, maintenance or inspection of this product, thoroughly read through and
understand this manual and the associated manuals. Also, take care to handle the module properly and
safely.
This manual classifies the safety precautions into two categories:
Depending on the circumstances, procedures indicated by
any case, it is important to follow all usage directions. Store this manual in a safe place so that it can be taken
out and read whenever necessary. Always forward it to the end user.
1. 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 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.
• At Forward/Reverse rotation limits, make sure to wire the contacts with NC, negative-logic. Wiring contacts with NO,
positive-logic may cause serious accidents.
• Make sure to observe the following precautions in order to prevent any damage to the machinery or accidents due
to abnormal data written to the PLC under the influence of noise:
1) Do not bundle the main circuit line together with or lay it close to the main circuit, high-voltage line or load line.
Otherwise, noise disturbance and/or surge induction are likely to take place. As a guideline, lay the control line
at least 100mm (3.94") or more away from the main circuit or high-voltage lines.
2) Ground the shield wire or shield of the shielded cable at one point on the PLC. However, do not ground them at
the same point as the high-voltage lines.
• Install module so that excessive force will not be applied to the built-in programming connectors, power connectors
or I/O connectors. Failure to do so may result in wire damage/breakage or PLC failure.
2. INSTALLATION PRECAUTIONS
• Make sure to cut off all phases of the power supply externally before attempting 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 cause severe injury. In
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