B-64044EN/01 CONNECTION 1.CONNECTING THE DeviceNet
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1.7.6 Sharing the Power Supply with the NC
Basically, the power supply for communication cannot also be used
for the NC. Prepare a separate power supply for each unit.
However, when it is inevitable to share one power supply for cost or
space reasons, keep the following in mind.
The minimum voltage in the input voltage specification of an NC
power supply (24 VDC input type) is 21.6 V, which is higher than that
of the power supply for communication. The input voltage
specification must be satisfied while considering loss due to a voltage
drop by cables. In addition, if a communication cable is broken or a
ground fault occurs when one power supply is shared, the control unit
of the NC will be powered off.
When a power supply is prepared for each unit, turn on or off the
power of the units in the order specified below.
・ Turn of the power supply for communication before or
concurrently with the NC power supply.
・ Turn off the power supply for communication after or
concurrently with the NC power supply of the master station.
If only the power supply for communication is turned off during
operation of a network, an error may occur on another node being