The UVCS flight software resides in the REU. The software performs the following functions: (1) instrument control; (2) spacecraft interface; (3) mechanism control; and (4) image processing. The instrument control software includes software for all observing and standby modes. This includes ``housekeeping'' software to monitor instrument health and to safeguard the instrument against over-exposure of detectors by direct sunlight. The spacecraft interface software is responsible for reception of commands and telemetry of science and housekeeping data. Mechanism control software performs the functions required to safely operate instrument mechanisms. Image processing software performs the functions related to the operations of the image processors (loading of detector masks, taking an exposure).
The flight software provides the user with the capability to operate the instrument interactively (only during contact periods) or in batch mode. Most UVCS observations will be performed by executing ``observation sequences'' stored in onboard memory. The sequences contain detailed information about UVCS instrument configuration, exposure times, etc. Occasionally new or revised sequences will need to be generated and uplinked in order to address specific scientific objectives or correct for problems with the instrument. The UVCS workstations at the EOF contain the software tools needed to generate, uplink and verify new sequences and associated parameter data.