4 Installation and Wiring
4 - 32
NX-series Analog I/O Units User’s Manual for Analog Input Units and Analog Output Units (W522)
If you use Analog Input Units that take differential input, when more than one input device is using the
same power supply, and voltage input is being supplied, a disconnection will occur as follows.
If a disconnection occurs in section A in the figure above, unwanted voltage paths occur as indicated by
the arrow. As a result, about 1/3 to 1/2 of the voltage between C and D, which is normally connected, is
generated between A and B. The same applies when B is disconnected.
When this kind of voltage is generated, disconnection detection may not work.
When voltage input is being supplied, either set up the input devices so that they are not using the
same power supply, or use isolators for each input.
This does not apply when current input is being supplied.
4-4-3
Precautions when Using Common Power Supply for Input
Devices of Analog Input Units
Analog Input Unit
Voltage
generated
Internal
circuits
Input
device
Input
device
Power
supply
Input n+
Input n
−
A
B
AG
C
D
Input n+
Input n
−
Summary of Contents for NX-AD series
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