National Instruments SCXI-1121 Manuel D’Utilisation

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.

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.

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.

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.

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.

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, 

. The connector has eyelet 

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, 

, 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.