PCIe-DIO6400 Users Manual (Rev 1.0)
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http://www.daqsystem.com
3. Digital Input Circuit
IN_COM0
DIN0
in0
2.4K
VCC
DIN1
in1
VCC
DIN7
In7
VCC
2.4K
2.4K
[Figure 3-1. Digital Input Circuit]
Figure 3-1 shows that digital input is isolated by photo-coupler. When applying plus(+) voltage to
“IN_COM0”, and applying minus(-) voltage to digital input(DIN0 ~ DIN7), the current is flowing through
diode in the inside to photo-coupler and an output direction transistor is applied an electric current
according to flow electric current.
There are 4 circuits as above picture to a board. In other words, there is a IN_COM signal each 8
photo-couplers, total IN_COM signals are 4 (IN_COM0 ~ IN_COM3).
If you want completely isolated circuit, it is good to use the external power better than to use the
board power.
