Excitation channels, Temperature sensor connection, Connector-and-shell assembly – National Instruments SCXI-1121 User Manual
Page 38
Chapter 2
Configuration and Installation
2-22
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Warning
Exceeding the input signal range and the common-mode input range results in
distorted signals. Exceeding the maximum input voltage rating (250 V
rms
between positive
and negative terminals and between any terminal and earth ground) can damage the
SCXI-1121, the SCXIbus, and the DAQ board. National Instruments is not liable for any
damages or injuries resulting from such signal connections.
Excitation Channels
Four fully isolated excitation channels are available. Each excitation
channel corresponds to an input channel. A 250 V
rms
isolation barrier exists
between two corresponding channels (for example, between input
channel 0 and excitation channel 0). In addition, the excitation outputs are
overvoltage protected to 250 V
rms
with current foldback.
Warning
Exceeding the overvoltage protection or isolation rating on the excitation output
can damage the SCXI-1121, the SCXIbus, and the DAQ board. National Instruments is not
liable for any damages or injuries resulting from such signal connections.
Temperature Sensor Connection
Pins C2 and C4 are dedicated for connecting the temperature sensor to the
SCXI-1121. The temperature sensor is not isolated and is referenced to
chassis ground. The connection is overvoltage-protected to ±25 VDC with
power on and ±15 VDC with power off.
Warning
Exceeding the overvoltage protection on the temperature connections can
damage the SCXI-1121, the SCXIbus, and the DAQ board. National Instruments is not
liable for any damages resulting from such signal connections.
Connector-and-Shell Assembly
Two types of signal connectors are available to connect the transducers to
the SCXI-1121 inputs. The first, the SCXI-1330 32-pin DIN C female
connector-and-shell assembly, is available in a kit listed in the
section in Chapter 1,
ends for easy hook-and-solder wire connection. With this kit, you can build
your own signal cable to connect to the SCXI-1121 inputs. After you have
built the cable, the shell covers and protects the connector. Perform the
following steps to assemble and mount the connector-and-shell assembly
to your SCXI module:
1.
Refer to Figure 2-8,
Assembling and Mounting the SCXI-1330
, and the diagram included with your
SCXI-1330 kit to build the connector-and-shell assembly.
2.
Turn off the computer that contains your DAQ board or disconnect the
board from your SCXI chassis.