Chapter 4
Connecting and Using Accessories and Transducers
4-22
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Excitation Channel Signal Connections on the
SCXI-1122
The SCXI-1122 has a voltage (VEX) and a current excitation (IEX)
channel, which are available at the front connector. In addition, VEX/2 is
available for half-bridge and quarter-bridge transducers. Both channels are
isolated from earth ground up to 450 V
rms
working common-mode voltage.
Notice that the voltage and current excitation channels are electrically
isolated from each other but do not provide a safety isolation between them.
Warning
Exceeding the overvoltage protection or isolation rating on the excitation output
can damage the SCXI-1122, the SCXIbus, and the DAQ device. National Instruments is
not liable for any damages or injuries resulting from such signal connections.
Excitation Level
Each excitation channel of the SCXI-1122 has one level:
•
Current excitation—1 mA
•
Voltage excitation—3.333 V
It is important that you do not exceed the maximum permissible load of
each channel as listed in Table 4-4.
Table 4-4.
SCXI-1122 Maximum Load per Excitation Channel
Excitation Level
Maximum Load
3.333 V
1 mA
225 mA
5 k
Ω
