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3.2 Isolated Input Ports (LTC, INCOM)
There are 4 pairs of isolated input ports on PCI-8124. Each pair
has two terminals. One is INCOMx, and the other is LTCx.
Because the input port of the photo coupler utilized on PCI-8124 is
single-directional, LTC signal must be lower than INCOM signal.
When there is a differential voltage between LTCx and corre-
sponding INCOMx, the photo coupler will turn on immediately.
There is an internal resistor in the PCI-8124 circuit as figure shows
below. So it is not necessary to attach additional resistor con-
nected outside the PCI-8124. The forward current of input signal is
7.5mA to 12.5mA. The typical forward voltage is 1.65V, and the
maximum forward voltage is 1.9V. So users should calculate the
appropriate voltage applied on LTCx and INCOMx.
Outside PCI-8124
INCOMx
LTCx
18
CN1 Pin No.
Name
1
INCOM1
3
INCOM2
30
INCOM3
32
INCOM4
2
LTC1
4
LTC2
27
LTC3
29
LTC4
inside PCI-8124
7.5mA to 12.5mA
2.2KΩ
Max 30mA
Description
In1 Com
In2 Com
In3 Com
In4 Com
Isolated Latch 1
Isolated Latch 2
Isolated Latch 3
Isolated Latch 4
Signal Connections
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