National Instruments NI 9476 - Manual (Page 7)

© National Instruments Corp. 7 NI 9476 Operating Instructions and Specifications
Each channel has a DO pin to which you can connect a digital input
device. The 32 digital output channels are internally referenced to
COM.
You must connect an external power supply to the NI 9476. The
power supply provides the current for the output channels. Connect
the positive lead of the power supply to the supply pin, V
sup
, and
the negative lead of the power supply to the common pin, COM.
Refer to the
Specifications section for information about the power
supply voltage range.
Note The V
sup
pins are internally connected. You can
connect only one external voltage supply to the device.
Caution Do not remove or insert modules if the external
power supply connected to the V
sup
and COM pins is
powered on.
The NI 9476 has current sourcing outputs, meaning the DO pin is
driven to V
sup
when the channel is turned on.