User`s manual

20 PCI-1753 User's Manual
If the jumper JP1 is enabled and the initial configuration is caused by
a reset, all ports will return to the states they had just prior to the reset.
The reset must be a "hot" reset (power not disconnected) for enabled
JP1 to return ports to their prior values. Otherwise, the card behaves
as though JP1 were not enabled. Please refer to "Jumper settings" in
Chapter 2 for more information.
3.2.5 Dry Contact Support for Digital Input
Each digital input channel accepts either dry contact or 0 ~ 5 V
DC
wet
contact inputs. Dry contact capability allows the channel to respond
to changes in external circuitry (e.g., the closing of a switch in the
external circuitry) when no voltage is present in the external circuit.
Figure 3-1 shows external circuitry with both wet and dry contact
components, connected as an input source to one of the card's digital
input channels.
Figure 3-1: Wet and dry contact inputs
Note!: For wet contact configurations, a malfunction may occur
if the internal resistance of the voltage source is signifi-
cant (> 1.5 k Ω ). It is advisable to connect a 1.5 k Ω
resistor in parallel with such a voltage source to avoid a
voltage rise inside the voltage source.
1.5 K
Ω
0.5 W
PC 5V
10 K
Ω
Buffer
Dry Contact: Open High
Close Low
Wet Contact: 2.0~5.25 V
DC
High
0~0.8 V
DC
Low
External Internal
Resistor
in
Parallel