Omron SYSMAC CJ1W-SCU21-V1, Operation Manual

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Application Precautions 5
5 Application Precautions
Observe the following precautions when using the PLC System.
!WARNING
Always heed these precautions. Failure to abide by the following precautions
could lead to serious or possibly fatal injury.
• Always connect to a ground of 100
Ω
or less when installing the Units. Not
connecting to a ground of 100
Ω
or less may result in electric shock.
• Always turn OFF the power supply to the PLC before attempting any of
the following. Not turning OFF the power supply may result in malfunction
or electric shock.
• Mounting or dismounting Power Supply Units, I/O Units, CPU Units,
Serial Communications Units, or any other Units.
• Assembling the Units.
• Setting DIP switches or rotary switches.
• Connecting cables or wiring the system.
• Mounting or dismounting terminal blocks.
!Caution Failure to abide by the following precautions could lead to faulty operation of
the PLC or the system, or could damage the PLC or PLC Units. Always heed
these precautions.
• Fail-safe measures must be taken by the customer to ensure safety in the
event of incorrect, missing, or abnormal signals caused by broken signal
lines, momentary power interruptions, or other causes.
• Take appropriate measures to ensure that the specified power with the
rated voltage and frequency is supplied. Be particularly careful in places
where the power supply is unstable. An incorrect power supply may result
in malfunction.
• Tighten the mounting screws at the bottom of Serial Communications
Units to a torque of 0.4 N
⋅
m. An incorrect tightening torque may result in
malfunction.
• Leave the label attached to the Unit when wiring. Removing the label may
result in malfunction if foreign matter enters the Unit.
• Remove the label after the completion of wiring to ensure proper heat dis-
sipation. Leaving the label attached may result in malfunction.
• Always check polarity before wiring RS-422A/485 connectors. The polar-
ity for the SDA/B and RDA/B signals can be different for some external
devices.
• Check to be sure that terminating resistors have been correctly installed
for RS-422A/485 systems before starting operation.
• Disconnect the LG terminal of the Power Supply Unit from the GR termi-
nal when performing insulation and dielectric strength tests.
• Never turn OFF the power supply while writing protocol macro data.
• Wire all connections correctly according to instructions in this manual.
• Check terminal blocks completely before mounting them.
• Double-check all wiring and switch settings before turning ON the power
supply. Incorrect wiring may result in burning.