
3. Connecting to an External Device
CNT16-8(FIT)GY, CNT16-8L(FIT)GY
13
External I/O Circuits
Input section
Figure 3.3 or 3.4 shows the input equivalent circuit for the interface section.
The signal input section consists of an opto-isolated input (compatible with both current sink output and
current source output). An external power supply is therefore required to drive the input section of this
module. The power requirement for the < CNT16-8(FIT)GY > is about 8 mA per input channel at
24 VDC (about 4 mA at 12 VDC) and for the < CNT16-8L(FIT)GY > is about 4 mA per input channel at
5 VDC.
Vcc
3k
Ω
3k
Ω
External circuit
Module
Optocoupler
Input
pin
Input
pin
+/-
common
Input contact
point
Input contact
point
12V - 24VDC
External
power supply
Optocoupler
Figure 3.3. Input Circuit < CNT16-8(FIT)GY >
Vcc
1.2k
Ω
1.2k
Ω
External circuit
Module
Optocoupler
Input
pin
Input
pin
+/-
common
Input contact
point
Input contact
point
Optocoupler
5VDC
External
power supply
Figure 3.4. Input Circuit < CNT16-8L(FIT)GY >