National Instruments BNC -2140 - Manual (Page 7)

© National Instruments Corporation 1-1 BNC-2140 User Manual
1
Introduction
This manual describes the electrical and mechanical aspects of the
BNC-2140 accessory and contains information concerning its operation.
This chapter describes the BNC-2140 accessory, lists what you need to get
started, explains how to unpack your BNC-2140, and describes optional
equipment.
The BNC-2140 is a signal conditioning accessory specifically designed for
use with a dynamic signal acquisition (DSA) device. It interfaces four BNC
signal inputs and two BNC signal outputs directly to National Instruments
DSA products including the PCI-4451, PCI-4452, NI 4551, and NI 4552.
The BNC-2140 connects to Integrated Circuit Piezoelectric (ICP
® )
accelerometers and microphone preamplifiers as well as any other
voltage source whose output is less than ±42.4 V.
Each input channel has an independent 4 mA current source suitable for
use with ICP-type accelerometers and microphone preamplifiers. You can
manually enable or disable the ICP signal conditioning on a per-channel
basis. With ICP disabled, a BNC-2140 input channel acts as a direct voltage
input. You can manually switch each input channel and each output channel
from differential (DIFF) to single-ended (SE) mode. In SE mode, the BNC
shell is tethered to a clean analog ground through a 50
Ω resistor.
The BNC-2140 receives power for ICP signal conditioning from the DSA
plug-in device through the 68-pin high-density connector. A green LED
indicates when the ICP circuitry is powered on. When you do not require
ICP signal conditioning, you can manually turn off the power to the
circuits.