Omron NX-ID3343 User Manual page 112

4 Installation and Wiring
 Precautions when Connecting a Two-wire DC Sensor
When a two-wire sensor is used with a DC Input Unit, check that the following conditions are met.
Failure to meet these conditions may result in operating errors.
(a) Relation between ON voltage of the DC Input Unit and sensor residual voltage
V ≤ V - V
ON CC
(b) Relation between input current to the DC Input Unit and sensor control output (load current)
I (min) ≤ I
OUT
I = (V - V
ON CC
When I is smaller than I
ON
be calculated as follows:
R ≤ (V - V
CC R
Power W of bleeder resistor ≥ (V
V : Input voltage of DC Input Unit
CC
V : Sensor's output residual voltage
R
I : Input current of DC Input Unit
ON
I : Sensor control output (load current)
OUT
R : Input resistor of DC Input Unit
IN
(c) Relation between OFF current of the DC Input Unit and sensor leakage current
I ≥ I
OFF leak
When I is greater than I
leak
Use the following equation to calculate the bleeder resistance constant.
R ≤ R × V
IN OFF
Power W of bleeder resistor ≥ (V
4 - 44
R
≤ I (max)
ON OUT
- 1.5 [internal residual voltage of DC Input Unit]) / R
R
(min), connect a bleeder resistor R. The bleeder resistor constant can
OUT
) / (I (min) - I )
OUT ON
- V
CC R
, connect a bleeder resistor R.
OFF
/ (I × R - V )
leak IN OFF
- V
CC
2
) / R × 4 [allowable margin]
2
) / R × 4 [allowable margin]
R
NX-series Digital I/O Unit User's Manual (W521)
IN