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•
The DIOx terminal is driven to the voltage supplied to DIO PWR when you turn on the channel,
and is driven to DGND when you turn off the channel.
•
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 21. Connecting a Device to the NI WSN-3226 in Drive High and Low Mode
Connecting Digital Inputs
You can connect a variety of sensors, switches, and industrial devices to the NI WSN-3226 device. Refer
to the
Specifications
24V Sinking
In 24V Sinking mode, the DIOx terminal has a low impedance to ground and input thresholds
compatible with 24 V signaling. Select this mode for connection to industrial 24V/IEC1131 sourcing
output devices.
24V Sinking with Power Management
In 24V Sinking with Power Management mode, the DIOx terminal is similar to 24V 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 μs 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 DIOx 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 DIOx terminal has TTL Logic 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.
© National Instruments Corporation
High Side Switch
DI
(Internal)
Low Side Switch
NI WSN-3226
section to ensure compatibility.
DIO PWR
DIOx
Device
DGND
23
NI WSN-3226 User Guide and Specifications
Drive Low (Sinking)
+
External
Power
–
Supply
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