Chapter 3
Configuring Your SCXI Hardware and Software
©
National Instruments Corporation
3-29
SCXI-1126 Module
The SCXI-1126 is a signal conditioning module with eight isolated
frequency input channels. Each channel of the SCXI-1126 includes a
frequency to voltage conversion circuit with programmable input range,
threshold, hysteresis, and filtering. Each channel is individually isolated
with a working common-mode voltage of 250 V
rms
between channels or
channel to earth ground. The SCXI-1126 is software configurable and
contains no jumpers.
SCXI-1140 Module
This module is an 8-channel simultaneously sampling differential
amplifier. The SCXI-1140 has an instrumentation amplifier that can track
and hold on all eight channels, an analog input range of ±10 V, and
individual DIP-switch-selectable channel gains of 1, 10, 100, 200, and 500.
DAQ Device Connections in Multiple-Module
Systems
Note
If you use an SCXI-1140 in a system that contains multiple SCXI modules and one
DAQ device, you must connect the SCXI-1140 to the DAQ device because the SCXI-1140
requires a counter/timer signal from the DAQ device to control the module track-and-hold
circuitry. Other modules do not use this signal and thus do not route the signal to the
SCXIbus.
If your system contains more than one SCXI-1140, the system operates
correctly only when you have connected one of the SCXI-1140 modules to
the DAQ device. Additional SCXI-1140 modules in the chassis can access
the counter/timer signal using that module and the SCXIbus backplane.
Other SCXI modules in the same chassis operate normally.
User-Configurable Jumpers and DIP Switches
This module has 10 user-configurable jumpers and eight DIP switches.
You can use the jumpers and switches to configure input signal referencing,
instrumentation amplifier output referencing, grounding, shielding, and
gain. Leave all other jumpers in their factory-default positions.
The SCXI-1140 is factory-configured for use with an AI or MIO device in
DIFF mode measuring ground-referenced signal sources—each module
channel is configured for a gain of 1. If this configuration is suitable for
your application, do not adjust any of the jumpers or DIP switches.