©
National Instruments
33
NI WSN-3214 User Guide and Specifications
•
If a supply voltage is not connected to DIO PWR, it operates as if it is set to the
mode.
•
Writing a digital value of 1 turns on the channel and writing a 0 turns the channel off.
Figure 33.
Connecting a Device to the NI WSN-3214 in Drive High and Low Mode
Connecting Digital Inputs
You can connect a variety of sensors, switches, and industrial devices to the NI WSN-3214 device. Refer
to the
section to ensure compatibility.
24 V Sinking
In 24 V Sinking mode, the DIO
x
terminal has a low impedance to ground and input thresholds
compatible with 24 V signaling. Select this mode for connection to industrial 24 V/IEC1131 sourcing
output devices.
24 V Sinking with Power Management
In 24 V Sinking with Power Management mode, the DIO
x
terminal is similar to 24 V Sinking mode,
but the low impedance path to ground is removed when the inputs are not being actively read. This can
reduce the power consumption of the output device. This mode should only be used with output devices
that have valid output states within 100
μ
s of having a low impedance path presented to the output.
TTL Logic
TTL Logic mode is suitable for most 3 V or 5 V logic signals. The DIO
x
terminal has high impedance
inputs with TTL Logic compatible thresholds.
Contact Closure
Contact Closure mode is suitable for connections to contact switches wired between the input and
ground. The DIO
x
terminal has
compatible thresholds and provides a pull-up resistor to 3 V
when the input is being read. If a contact to ground remains closed while the DIO Notification property
is enabled, the current into the contact switch increases power consumption and can reduce battery life.
Digital I/O Protection
The high side switch on each I/O channel has short circuit protection. The low side switch on each I/O
channel is oversized to be able to withstand higher currents than when in normal operating conditions.
DIO
x
DGND
Extern
a
l
Power
Su
pply
+
–
Device
DIO PWR
High
S
ide
S
witch
Low
S
ide
S
witch
DI
(Intern
a
l)
NI W
S
N-
3
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