Figure 2. Connecting Digital Devices to the NI-9403
TTL Signal
+5 V
+5 V
LED
DIO0 as Input
DIO1 as Input
COM
DIO2 as Output
NI 9403
Device 3
Device 2
Device 1
Overcurrent/Short-Circuit Protection
The overcurrent protection allows only a specified amount of current through the
output channels to protect the NI-9403 from short circuits. If the NI-9403 goes into
an overcurrent state, the module sets all the DIO channels to high impedance for
approximately 280 ms.
When the channels are in an overcurrent state, the NI-9403 can accept new line
direction configuration and output state data but cannot pass valid input data to the
software.
After the overcurrent protection period, the NI-9403 automatically recovers to the
latest direction configuration and output state. If the overcurrent condition still
exists, the module again sets the channels to high impedance. This cycle continues
until the overcurrent condition is removed.
Where to Go Next
ni.com
8
NI-9403 Getting Started
