Mitsubishi Electric NZ2GN2S1-32D - Page 204

202
11 TROUBLESHOOTING
11.5 Examples of Troubles with the I/O Module
■Calculation example
If the switch with LED indicator with maximum leakage current of 3mA when 24VDC external power supply is provided to the
NZ2GN2B1-32D is connected
1. The OFF current of NZ2GN2B1-32D is not 1.5mA or lower. Therefore, connect a resistor as shown below.
2. To satisfy the condition that the OFF current of NZ2GN2B1-32D is 1.5mA or lower, the current through the connected
resistor should be 1.5mA or higher. From the formula below, the connected resistor (R) is lower than 3.0k.
3. When the resistor (R) is 2.5k, for example, the power capacity (W) of the resistor (R) becomes 0.332W.
4. Because the resistor requires a power capacity that is 3 to 5 times larger than the actual current consumption, the
resistor connected to the terminal should be 2.5k; and 1 to 2W.
5. OFF voltage when the resistor (R) is connected becomes 4.09V. This satisfies that the OFF voltage of NZ2GN2B1-32D
is 5V or lower.
Input module
Leakage current 3mA
24VDC
I
R
=1.5mA R
I
Z
=1.5mA
3mA
24VDC
3.0kΩ
Input impedance
I
R
: I
Z
= Z (Input impedance): R
R ≤ × Z (Input impedance) = × 3.0 = 3.0[kΩ]
I
R
I
Z
1.5
1.5
W = (Input voltage)
2
÷ R = 28.8
2
÷ 2500 = 0.332[W]
× 3[mA] = 4.09[V]
2.5[kΩ]
1
3.0[kΩ]
1
+
1