National Instruments NI 9229E - Manual (Page 5)

© National Instruments Corp. 5 NI 9229E/9239E
The NI 9229E /9239E has four 2-terminal detachable
screw-terminal connectors.
Note You must use 2-wire ferrules to create a secure
connection when connecting more than one wire to a
single terminal on the NI 9229E /9239E.
You can connect ground-referenced or floating signal sources to
the NI 9229E/9239E. Connect the positive signal of the signal
source to the AI+ terminal, and connect the negative signal of the
signal source to the AI– terminal. If you make a ground-referenced
connection between the signal source and the NI 9229E/9239E,
make sure the voltage on the AI+ and AI– connections are in the
channel-to-earth safety voltage range to ensure proper operation of
the NI 9229E/9239E. Refer to the
Specifications section for more
information about operating voltages and overvoltage protection.
Refer to Figures 3 and 4 for illustrations of how to connect
grounded and floating signal sources to the NI 9229E/9239E.