National Instruments NI 9425 - Manual (Page 9)

© National Instruments Corp. 9 NI 9425 Operating Instructions and Specifications
Figure 2. Connecting a Device to the NI 9425 (Three-Wire Device Shown)
The NI 9425 channel registers as ON when the sourcing-output
device applies a voltage or drives a current that is in the input ON
range to the DI pin. The channel registers as OFF when the device
applies a voltage or drives a current that is in the input OFF range
to the DI pin. If no device is connected to the DI pin, the channel
registers as OFF. Refer to the
Specifications section for more
information about the ON and OFF states.
NI 9425
+
_
COM
DI
Sourcing-Output
Device
External
Power
Supply