National Instruments NI 9401 - Manual (Page 10)

NI 9401 Operating Instructions and Specifications 10 ni.com
Overcurrent Protection
Overcurrent protection on the NI 9401 allows only a specified
amount of current for switching DIO channels or sourcing the
output load. If the NI 9401 goes into an overcurrent state, by
exceeding the specified maximum switching frequency or the
output load, the module power supply begins to drop in voltage
until it completely turns off or the overcurrent condition is
removed. When the module is in this state, it can accept new line
direction configuration and output state data but cannot pass valid
input data to the software. Refer to the
Specifications section for
more information about the maximum switching frequency and
output load for each channel.