Mitsubishi Electric MELSEC iQ-F Series User Manual page 96

■ In the case of 2-wire proximity switch
Use a two-wire proximity switch whose leakage current, I is 1.5 mA or less when the switch is off.
If the resistance is larger than leakage current, I of 1.5 mA, connect a bleeder resistance Rb (kΩ), obtained by the following
formula as shown in the following figure.
Item
Bleeder resistance Rb (kΩ)
24V
S/S
PLC
X
(sink input)
0V
■When the input signal cannot be received because the current is insufficient
The current rating for the CPU module in X10 or more and the I/O module is 4 mA.
In some cases, depending on extension devices used, it may not be possible to receive the input signal, due to the insufficient
current. Take the following action in such case.
PLC
5.6 k
X
S/S
External resistor
(for input current adjustment)
In the case of capturing high-speed pulses
When capturing pulses of a response frequency of 50 to 100 kHz on input X0, X1, X3 and X4, wire the terminals as stated
below.
• The wiring length should be 5 m or less.
• Use shielded twisted-pair cables for connecting cables. Ground the shield of each shielded cable only on the CPU module
side.
• Connect a 1.5 kΩ (1 W or more) bleeder resistance to the input terminal, so that the sum of the load current of the open
collector transistor output on the mating device and the input current of the CPU module is 20 mA or more.
The above-mentioned restrictions are due to specifications of connecting device (encoder etc.).
Please adjust the cable length and load, for connecting device.
6 WIRING
94
6.5 Input Wiring
CPU module
Input module, Input/output modules, Powered input/output module
Bleeder
resistance
2-wire
proximity
Rb
I
sensor
Input current
Adjusted in accordance
with the connected device
Proximity sensor
X0 to X7
X10 and subsequent
0V
S/S
I
PLC
X
(source input)
24V
Specifications
7 / (I-1.5) or less
9 / (I-1.5) or less
Bleeder
resistance
2-wire
proximity
Rb
sensor