National Instruments NI 9475 - Manual (Page 7)

© National Instruments Corp. 7 NI 9475 Operating Instructions and Specifications
Each channel of the NI 9475 has a DO pin to which you can
connect a device. Each channel also has a COM pin and a V
sup
pin.
National Instruments recommends you provide independent COM
and V
sup
wiring for each channel to minimize current flow in the
COM and V
sup
wiring. The COM pins are all connected together
internally.
Each channel has an LED that indicates the state of the channel.
When a channel LED is lit, the channel is on. When the LED is
dark, the channel is off.
You must connect an external power supply to the NI 9475. 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. 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 9475 has current sourcing outputs, meaning the DO pin is
driven to V
sup
when the channel is turned on.