Omron SYSMAC Operation Manual page 15

Application 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.
• Construct a control circuit so that power supply for the I/O circuits does
not come ON before power supply for the PLC. If power supply for the I/O
circuits comes ON before power supply for the PLC, normal operation
may be temporarily interrupted.
• If the operating mode is changed from RUN or MONITOR mode to PRO-
GRAM mode, with the IOM Hold Bit ON, the output will hold the most
recent status. In such a case, ensure that the external load does not
exceed specifications. (If operation is stopped because of an operation
error (including FALS instructions), the values in the internal memory of
the CPU board will be saved, but the outputs will all turn OFF.)
• Always use the power supply voltage specified in the operation manuals.
An incorrect voltage may result in malfunction or burning.
• Take appropriate measures to ensure that the specified power with the
rated voltage is supplied. Be particularly careful in places where the
power supply is unstable. An incorrect power supply may result in mal-
function.
• Install external breakers and take other safety measures against short-cir-
cuiting in external wiring. Insufficient safety measures against short-cir-
cuiting may result in burning.
• Do not apply voltages to the input terminals in excess of the rated input
voltage. Excess voltages may result in burning.
• Do not apply voltages or connect loads to the output terminals in excess
of the maximum switching capacity. Excess voltage or loads may result in
burning.
• Be sure that all the mounting screws, terminal screws, and cable connec-
tor screws are tightened to the torque specified in the relevant manuals.
Incorrect tightening torque may result in malfunction.
• When wiring the CPM2B, take countermeasures to prevent wiring cuttings
from coming into contact with the product, such as covering the whole
product with a dustproof cover. If wiring cuttings adhere to the PCB or cir-
cuit elements they may cause short-circuiting.
• Be sure to perform wiring in accordance with the relevant operation man-
ual. Incorrect wiring may result in burning.
• Double-check all the wiring before turning ON the power supply. Incorrect
wiring may result in burning.
• Be sure that the terminal blocks, expansion cables, and other items with
locking devices are properly locked into place. Improper locking may
result in malfunction.
• Be sure that terminal blocks and connectors are connected in the speci-
fied direction with the correct polarity. Not doing so may result in malfunc-
tion.
• Check the user program for proper execution before actually running it on
the PLC. Not checking the program may result in an unexpected opera-
tion.
• Confirm that no adverse effect will occur in the system before attempting
any of the following. Not doing so may result in an unexpected operation.
• Changing the operating mode of the PLC.
• Force-setting/force-resetting any bit in memory.
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