ADLINK PCI-7432 - Manual (Page 33)

Operation Theory
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4
Operation Theory
4.1 Isolated Digital Input Channels
The isolated digital input has an open collector transistor structure. The input
voltage range is 0V to 24V (0V to 50V for PCI-7433) and the input resistance
is 2.4K
Ω
(4.7K
Ω
for PCI-7433). The connection between external signals
and the 7432/33 is shown in Fig 12. Please note that the input common
junction could be common ground or common power, they are dependent on
the user’s environment. Therefore, the digital input could be either a current
source or a current sink.
2.4K Ohm
Isolated Input
Signal (source)
COM m
(GND)
Current Flow
2.4K Ohm
Isolated Input
Signal (sink)
COM m
(+VDD)
Current Flow
Figure 12: Isolated input connection