Omron NJ501-1400 User Manual page 160

4 Installation and Wiring
 AC Input Units
Contact output
AC Switching
Proximity
switch
main
circuit
Precautions for Correct Use Precautions for Correct Use
When using a reed switch as the input contact for an AC Input Unit, use a switch with an allow-
able current of 1 A or greater. If reed switches with smaller allowable currents are used, the con-
tacts may fuse due to surge currents.
 Precautions when Connecting a Two-wire DC Sensor
When using a two-wire sensor with a 24-VDC input device, check that the following conditions have
been met. Failure to meet these conditions may result in operating errors.
(1) Relation between voltage when the Controller is ON and the sensor residual voltage:
V
ON
(2) Relation between voltage when the Controller is ON and sensor control output (load
current):
I
OUT
I = (V
ON
When I
stant can be calculated as follows:
R  (V
Power W  (V
V : ON voltage to Input Unit
CC
V : Sensor output residual current
R
I : Input Unit ON current
ON
I : Sensor control current (load current)
OUT
R : Input Unit input impedance
IN
4-40
IN
AC Input Unit
COM
IN
AC Input Unit
COM
 V  V
CC R
(min)  I  I
(max.)
ON OUT
 V  1.5 [Controller internal residual voltage])/R
CC R
is smaller than I
ON OUT
 V (min.)  I
)/(I
CC R OUT
2
 V /R  4 [allowable margin]
)
CC R
(min), connect a bleeder resistor R. The bleeder resistor con-
)
ON
NJ-series CPU Unit Hardware User's Manual (W500)
IN