Digital Output Module Operating Instructions and Specifications

I/O Protection

The NI 9476 is protected against overcurrent, inrush, and

short-circuit conditions in accordance with IEC 1131-2.

Understanding Protected Devices

Each channel on the NI 9476 has circuitry that protects it from

voltage and current surges resulting from short circuits.

Caution The NI 9476 can be damaged under overvoltage

and reverse bias voltage conditions. Check the voltage

specifications for all devices that you connect to the

NI 9476.

Excessive current through a DO pin causes the channel to go into

an overcurrent state. In an overcurrent state, the channel cycles off

and on until the short circuit is removed or the current returns to an

acceptably low level. Refer the Specifications section for typical

trip currents.

Each channel has a status line that indicates in software whether the

channel is in an overcurrent state. Refer to the software help for

information about reading output status.