NI WSN-3226 User Guide and Specifications
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Understanding Short Circuit Protection
The current that flows through the high side switch is continuously sensed. If a current above the trip
limit is detected, the current protection trips and turns off the high side switch. The protection latches in
the tripped state and only resets when the high side switch is given the command to turn off. High inrush
currents that exist for a short time do not trip the short-circuit protection. Refer to the
section for more information about the maximum continuous output current, short circuit behavior, and
short circuit trip time.
Preventing an Overcurrent Condition
Follow these recommendations to prevent an overcurrent condition:
•
Do
not
connect DIO PWR to ground.
•
Do
not
ground unused terminals.
•
Do
not
exceed the output current rating of the channel.
•
Do
not
exceed the voltage ratings of the channel.
Detecting a Overcurrent Condition
To check whether or not the short circuit protection is tripped, the logic state of the DIO pin can be read
when driving high using the digital input function. If DO is set to
and Low (Sinking and Sourcing)
modes and a digital value of 1 is written to the channel, a logical 1
should be read from the channel. If a logical 0 is read instead, then the current protection is tripped or a
fault is preventing the high side switch from driving the output high.
Resetting Channels After an Overcurrent Condition
To reset the short circuit protection turn off the high side switch by writing a digital value of 0 to the
channel. Then, check the wiring and remove any possible faults. The correct functionality of the circuit
should be confirmed by writing a digital value 1 to the channel and then reading a logical 1 from it.
Powering an External Sensor
The NI WSN-3226 can provide up to 50 mA at 12 V to external sensors through its sensor power
(SEN PWR 12V) terminal. You can configure this sensor power output using NI-WSN software to turn
on a sensor up to 250 ms prior to the start of an acquisition. Figure 22 shows the sensor power circuit
connected to a device.
Figure 22.
External Sensor Connected to the NI WSN-3226
Make sure the device you are connecting is compatible with the NI WSN-3226 sensor power circuit
voltage and current ranges. Refer to the
section for more information.
NI W
S
N-
3
226
AI
COM
S
EN PWR 12V
Powered
S
en
s
or
