Panasonic AFP7X16DW User Manual page 40

Wiring
Connection of LED-equipped limit switch
With the LED-equipped limit switch, if the input of the PLC is not turned off or if the LED of the
limit switch is kept on because of the leakage current, the connection of a bleeder resistor is
recommended, as shown below.
Using 16-point type input unit (AFP7X16DW)
(Off voltage: 2.5 V; input impedance: 3.6kΩ)
r: Internal resistor of limit switch (kΩ)
R: Bleeder resistor (kΩ)
The input off voltage is 2.5 V. Therefore, when the power supply voltage is 2.4 V,
the input impedance is 3.6kΩ.
2.4-2.5
I ×
r
Obtain R so that the above current will flow. Obtain I in the same way as when using
the above 2-wire sensor.
9
R≤
3.6I-2.5
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3-4
or more
(Power supply voltage)
(kΩ) W=
R
2
×(3 to 5)