Precautions When Connecting a Two-wire DC Sensor
When a two-wire sensor is used with the trigger inputs of the High-speed Analog Input Units, check
that the following conditions are met. Failure to meet these conditions may result in operating errors.
Relation between ON Voltage at Trigger Inputs and Sensor Residual Volt-
age
The trigger inputs of the High-speed Analog Input Units can detect sensor output ON only when the
following conditions are satisfied:
V
ON
≤ V
CC
- V
R
The voltages related to the conditions for NPN type sensors are shown in the figure below.
IN
*
IOG
IOV
IOG
*
IOV
*
V
R
V
CC
V
ON
Two-wire sensor
Unit that can supply I/O power
to the NX bus
High-speed Analog Input Unit
The voltages related to the conditions for PNP type sensors are shown in the figure below.
IOG
IOV
IOG
*
IOV
*
IN
*
Two-wire sensor
V
R
V
CC
V
ON
High-speed Analog Input Unit
Unit that can supply I/O power
to the NX bus
V
CC
: Power supply voltage
V
R
: Sensor's output residual voltage
V
ON
: ON voltage at trigger input of the High-speed Analog Input Unit
4 Installation and Wiring
4 - 27
NX-series Analog I/O Units User’s Manual for High-speed Analog Input Units (W592)
4-4 W
iring External Devices
4
4-4-3
Precautions for Wiring
