National Instruments NI 9472 - Manual (Page 10)

NI 9472/9474 10 ni.com
You must connect an external power supply to the NI 9472/9474.
This power supply provides the current for the devices you connect
to the module. Connect the positive lead of the power supply to
V
sup
and the negative lead of the power supply to COM. The V
sup
pins on the NI 9472 with DSUB are internally connected. You can
connect only one external voltage supply to the device. Refer to the
Specifications section for information about the power supply
voltage range.
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 9472/9474 has current sourcing outputs, meaning the DO
terminal or pin is driven to V
sup
when the channel is turned on.