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National Instruments Corporation
2-1
2
Connecting Signals
This chapter describes the input and output signals connections to the
SCXI-1125 module with the module front connector and the rear signal
connector. This chapter also includes specifications and connection
instructions for the signals on the SCXI-1125 module connectors.
Notes
Refer to the
Read Me First: Safety and Radio-Frequency Interference
document
before removing equipment covers or connecting or disconnecting any signal wires.
For EMC compliance, operate this device with shielded cabling.
The isolated channels of the SCXI-1125 allow you to make precision
high-voltage measurements or low-voltage measurement of signals riding
on high common-mode voltages while protecting sensitive computer parts
and equipment connected to the module. The isolated amplifiers fulfill
two purposes on the SCXI-1125 module. First, they can convert a small
signal riding on a high common-mode voltage into a single-ended signal
with respect to the SCXI-1125 chassis ground. With this conversion, you
can extract the analog input signal from a high common-mode voltage
before sampling by the E/M Series DAQ device. Second, the isolation
amplifier amplifies and filters an input signal resulting in increased
measurement resolution and accuracy. The following sections explain how
to make signal connections to maximize the effectiveness of the
SCXI-1125 for conditioning analog signals.
AC and DC Voltage Connections
You can make input signal connections to the SCXI-1125 through the front
signal connector or through accessory terminal blocks. Chapter 1,
, contains a list of SCXI-1125-compatible terminal blocks.
Terminal blocks have features such as screw-terminal connectivity, BNC
connectivity, cold-junction temperature measurement, and attenuation.
The pin assignment for the SCXI-1125 front signal connector is shown in
Table 2-1. The positive input terminal for each channel is in Column A and
the negative input terminal for each channel is in Column C. Input
connections to each channel are fully floating with respect to ground and
