National Instruments NI 9233, Руководство по эксплуатации

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© National Instruments Corp. 7 NI 9233 Operating Instructions and Specifications
Each channel has a BNC connector to which yo u can connect an
Integrated Electronic Piezoelectric (IEPE) sensor. The center pin
of the connector, AI+, provides the DC excitation and the AC
signal connection. The shell of the connector, AI–, provides the
excitation ret
u rn path and the AC signal gro u nd reference.
Yo u can connect gro u nd-referenced or floating IEPE sensors to the
NI 9233. Yo u can avoid picking u p gro u nd noise by u sing a floating
connection. Typical IEPE sensors have a case that is electrically
isolated from the IEPE electronics, so connecting the sensor to the
NI 9233 res
u lts in a floating connection even tho u gh the case of the
sensor is gro u nded. To f u rther minimize gro u nd noise, prevent
the metal shells of the BNC connectors from to u ching each other,
the mod u les, or the chassis.
If yo u make a gro u nd-referenced connection between the IEPE
sensor and the NI 9233, make s u re the voltage on the AI– shell
is in the common-mode range to ens u re proper operation of the
NI 9233. The AI– shell is protected against accidental contact
with overvoltages within the overvoltage protection range. Refer
to the
Specifications section for more information abo u t operating
voltages and overvoltage protection. Fig u res 2 and 3 ill u strate
connecting gro u nded and floating IEPE sensors to the NI 9233.