Agilent Technologies 8453 Operator's Manual page 137

Theory of Operation
Electronics Overview
SDA—Spectrophotometer Data Acquisition Board
On the SDA board, the signals from the photodiode array are adjusted to an
appropriate level and converted to digital values by a 16-bit A/D converter. In
addition, the SDA board controls the timing of the photodiode array. The
firmware automatically converts data points which are taken at a 0.9-nm
sampling interval from the diode array to deliver values at 1-nm interval to
the controller.
SSI—Spectrophotometer Sipper Interface Board
This board collects the signals from the push buttons and controls the
three-color LED located on the front panel of the spectrophotometer.
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