National Instruments 1142 用户手册

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The digital control circuitry contains a Module ID (identification) register, 
a configuration register for the module, a gain register, and an EEPROM 
for storing gain-calibration constants.

The Module ID register contains 20 (hex) for the SCXI-1141 module, 
35 (hex) for the SCXI-1142 module, and 34 (hex) for the SCXI-1143 
module. You can read this module ID over the SCXIbus to determine the 
type of module that is in a particular slot.

Use the configuration register to select channels and configure the 
SCXI-1141/1142/1143 module for scanning, calibration, and control 
options.

The gain register sets the gain of each amplifier. 

The frequency dividers control the filter cutoff frequency and the output 
clock frequency. For more information see the 

The EEPROM stores the calibration constants for each gain for all eight 
channels. Information in the EEPROM is retained when the module is 
power off. The SCXI-1141/1142/1143 module has calibration constants 
already stored in the EEPROM. You can modify these constants for your 
set of operating conditions. One set of constants is reserved and cannot be 
modified except at the factory, which ensures that you do not accidentally 
erase the default calibration constants. For more information on the 
EEPROM and calibration, see Chapter 5, 

The amplifiers provide gain to the differential signal between the inputs 
while rejecting common-mode noise voltages. The available gains are 1, 2, 
5, 10, 20, 50, and 100. The output range of the amplifiers is ±5 V. Select 
the gain to prevent the output signals from reaching ±5 V, or distortion 
occurs.

The input amplifiers are fully differential amplifiers with input protection 
and calibration circuitry. The inputs are protected against input voltages up 
to ±15 V powered off and ±30 V powered on.