72
For standard I/O Units:
7.2
2.4 x I – 3
––––––
R =
kΩ max.
W =
2.3
R
–––
W min.
I = leakage current in mA
The previous calculations are based on the following equations.
I
R
Input voltge (24)
Input current (10)
R )
Input voltage (24)
Input current (10)
v OFF voltage (3)
W w
Input voltage (24)
R
Input voltage (24) Tolerance (4)
When using a two-wire sensor with a 12-VDC or 24-VDC input device, check
that the following conditions have been met. Failure to meet these conditions
may result in operating errors.
1, 2, 3... 1. Relation between voltage when the PC is ON and the sensor residual volt-
age:
V
ON
x V
CC
– V
R
2. Relation between voltage when the PC is ON and sensor control output
(load current):
I
OUT
(min) x I
ON
x I
OUT
(max.)
I
ON
= (V
CC
– V
R
– 1.5 [PC internal residual voltage])/R
IN
When I
ON
is smaller than I
OUT
(min), connect a bleeder resistor R. The
bleeder resistor constant can be calculated as follows:
R x (V
CC
– V
R
)/(I
OUT
(min.) – I
ON
)
Power W y (V
CC
– V
R
)
2
/R × 4 [allowable margin]
Note The residual voltage in the PC is 4.0 V for the following Units:
C200H-ID211/ID212/IM211/IM212/INT01
The residual voltage is 1.5 V for all other Units.
Precautions when
Connecting a Two-wire
DC Sensor
Wiring
Section 3-2
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