National Instruments SCXI-1121 - Manual (Page 11)

© National Instruments Corporation 1-1 SCXI-1121 User Manual
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Introduction
This chapter describes the SCXI-1121; lists the contents of your
SCXI-1121 kit; describes the optional software, optional equipment, and
custom cables; and explains how to unpack the SCXI-1121 kit.
The SCXI-1121 consists of four isolated input channels and four isolated
excitation channels. The SCXI-1121 is a module for signal conditioning of
strain gauges, RTDs, thermistors, thermocouples, volt and millivolt
sources, 4 to 20 mA current sources, and 0 to 20 mA process-current
sources. The SCXI-1121 can operate in two output modes—the
Parallel-Output mode with all four input channels connected in parallel to
four data acquisition board channels, or the Multiplexed-Output mode with
all four channels multiplexed into a single data acquisition board channel.
The SCXI-1121 operates with full functionality with National Instruments
MIO-16 boards. The SCXI-1121 operates with full functionality with the
Lab-PC+ board in single-chassis SCXI systems. However, the Lab-PC+
cannot control multiple-chassis SCXI systems. You can use the Lab-NB,
the Lab-PC, the Lab-LC, and the PC-LPM-16 boards with the SCXI-1121,
but these boards can control only single-chassis SCXI systems and cannot
scan the module when it is configured in the Multiplexed-Output mode.
These boards can perform only single-channel reads in this mode. You can
also use the SCXI-1121 with other systems that comply with the
specifications given in Chapter 2,
Configuration and Installation . You can
multiplex several SCXI-1121s into a single channel, thus greatly increasing
the number of analog input signals that can be digitized.
The addition of a shielded terminal block provides screw terminals for easy
signal attachment to the SCXI-1121. In addition, a temperature sensor for
cold-junction compensation of thermocouples is included on the terminal
block. This cold-junction reference (CJR) is either multiplexed along with
the four input channels or connected by jumpers to a different channel of
the data acquisition board.
With the SCXI-1121, the SCXI chassis can serve as a fast-scanning signal
conditioner for laboratory testing, production testing, and industrial
process monitoring.