FPΣ User's Manual
6.4 Input and Output Wiring
85
In the actual selection, use a value that is 3 to 5 times the value of W.
Precaution when using an LED-equipped limit switch
If the input of the PLC does not turn off because of the leakage current from the LED-
equipped limit switch, the use of a bleeder resistor is recommended, as shown below.
COM
1
2
3
4
R
r
A
LED-equipped limit switch
3
Bleeder resistor
B
FPΣ
4
Input terminal
1
Internal circuit
r
Internal resistor of limit switch (kΩ)
2
Power supply for input
R
Bleeder resistor (kΩ)
The OFF voltage of the input is 2.4V. Therefore, when the power supply is 24V, select the
bleeder resistor R so that the current will be greater than the result of this formula:
I =
24 - 2.4
r
The resistance R of the bleeder resistor is:
(kΩ)
13.44R
5.6I - 2.4
R ≤
The wattage W of the resistor is:
(V)
2
R
W =
V = Power supply voltage
In the actual selection, use a value that is 3 to 5 times the value of W.
6.4.2 Output Wiring
Do not connect a load that exceeds the maximum switching ability of the output terminal.
To prevent the output circuits from being damaged by a short-circuit or other electrical
problems on the output side, transistors with short-circuit protection are provided (except for
Y0, Y1, Y3, and Y4 of the FPΣ CPU and FP0 expansion units).
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