Time bases, discretes, and interrupts

Abstract

The effort performed to assure proper flight program handling of time bases, discretes, and interrupts was discussed. The following time bases are used as key mission events: guidance reference release, liftoff, S-1B low level sensors dry, S-1B outboard engines cutoff, S-IVB cutoff, and S-IVB de-orbit DCS command. The five discrete outputs in the discrete output register were verified for proper setting. Each discrete input is honored in the proper time frame by forcing each discrete in the following intervals: before the discrete is enabled, after the discrete has been detected, and after the discrete has been disabled. As an assurance that an interrupt is honored only in the proper time frames, each interrupt was forced during the following intervals: prior to the specified enable time, after the interrupt has been honored, after the interrupt has been disabled.