NI WSN-3212 User Guide and Specifications
24
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Connecting Sinking Digital Outputs
Drive Low Only Mode
In Drive Low Only mode, the DIO.
x
terminal is pulled to D GND when you turn on the channel. Writing
a digital value of 0 turns on the channel, and 1 turns off the channel. The channel is high impedance when
the channel is turned off (1). Use this mode for devices that require low side drive or a sinking output.
Figure 25.
Connecting a Device to the NI WSN-3212 in Drive Low Only Mode
Connecting Digital Inputs
Tristate Mode
Use this mode to configure the channel as digital input, or for contact to ground sensing, as shown in
Figure 26. In Tristate mode, when DIO.
x
terminal is read, a weak pull-up resistor to internal 3.3 V is
enabled for about 1 ms.
Figure 26.
Example of Using the NI WSN-3212 in Tristate Mode
DIO.
x
D GND
Low
S
ide
S
witch
1
0
DI
(Intern
a
l)
Extern
a
l
Power
Su
pply
+
–
NI W
S
N-
3
212
Device
Cont
a
ct
S
witch
TTL
S
ign
a
l
NI W
S
N-
3
212
DI.
x
(Intern
a
l)
DI.
x
(Intern
a
l)
DI.
x
(Intern
a
l)
Extern
a
l
Power
Su
pply
Device
D GND
DIO.
x
DIO.
x
DIO.
x
D GND
D GND
+
–
