Omron NX1P2 series User Manual page 21

• Do not incline or twist the flat-blade screwdriver while it is in a release hole on a screwless clamping
terminal block of CPU Unit. Doing so may damage the terminal block.
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Terminal
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• The angle at which you insert a screwdriver in the release holes on the screwless clamping terminal
blocks of the CPU Unit is different from that on the screwless clamping terminal blocks of NX Units.
Check the wiring method for the NX Unit and perform wiring correctly.
Refer to the user's manual of the specific NX Unit for how to wire an NX Unit.
Power Supply Design
• Select an external power supply with sufficient capacity by considering the power supply capacity or
inrush current when the power is turned ON that is specified in this manual.
Otherwise, the external power supply may not be turned ON or malfunction due to unstable power
supply voltage.
• Use the I/O power supply current for the CPU Rack of NX1P2 CPU Unit at 4 A or less. Using the cur-
rents that are outside of the specifications may cause failure or damage.
• Use all Units within the I/O power supply ranges that are given in the specifications.
• Do not apply voltages that exceed the rated value to any Input Unit, slave, or input built in the CPU
Unit.
• Do not apply voltages or connect loads to the Output Units, slaves, or CPU Unit's internal outputs in
excess of the ratings.
• Surge current occurs when the power supply is turned ON. When selecting fuses or breakers for
external circuits, consider the above precaution and allow sufficient margin in shut-off performance.
Refer to this manual for surge current specifications.
• If the full dielectric strength voltage is applied or turned OFF using the switch on the tester, the gener-
ated impulse voltage may damage the Power Supply Unit. Use the adjustment on the tester to grad-
ually increase and decrease the voltage.
• Install external breakers and take other safety measures against short-circuiting and overcurrents in
external wiring.
Turning ON the Power Supply
• It takes approximately 20 seconds to enter RUN mode after the power supply is turned ON. During
that time, digital outputs on the CPU Rack will be OFF. The slave outputs behave according to the
setting values. Use the system-defined variables and the NX Unit device variables in the user pro-
gram to confirm that I/O data communications are established before attempting control operations.
External communications are also not performed during startup.
• Configure the external circuits so that the power supply to the control system turns ON only after the
power supply to the Controller has turned ON. If the power supply to the Controller is turned ON after
the control power supply, temporary errors may result in incorrect control system signals because the
output terminals on Output Units may momentarily turn ON when power supply is turned ON to the
Controller.
• If you transfer data from a backup file on an SD Memory Card to the Controller when the power sup-
ply is turned ON, properly select the data groups to transfer. If the data for an unintended data group
is transferred to the Controller, it may cause the equipment to operate unpredictably.
• You cannot obtain normal input data from NX Units while the Units are restarting. Use the sys-
tem-defined variables or device variables for the NX Units on the CPU Unit in the user program to
check the validity of the I/O data before you attempt control operations.
NX-series NX1P2 CPU Unit Hardware User's Manual (W578)
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Terminal
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Precautions for Safe Use
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