National Instruments SCXI-1121 Manuel D’Utilisation

Page de 162
© National Instruments Corporation
1-1
1
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, 
. 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.