The characteristics of application control software for a space station sensor and effector simulator

Spaceborne devices demand high standards of reliability that in turn, must be met by rigorous testing. The multiplexers/demultiplexers (MDMs) used on the International Space Station for measurement and control represent a typical example of these devices. In order to test the MDMs, and in order to support development and testing of MDM software. It became necessary to develop an SES (sensor and effector simulator) system consisting of a primarily COTS, VXI based, SES hardware console, and SES application control software, programmed in C and running under Windows 95. The SES system simulates external equipment in real time, by generating sensor stimulus to the MDM and by receiving effector responses from the MDM. The SES application control software supports the simulation process by responding to SCSI commands from the simulation environment. The SES responds to these commands by formatting and controlling the application of sensor stimulus commanded by the simulation environment, and by formatting and transmitting effector responses to the simulation environment. This permits the SES system to operate in a real time loop consisting of the simulation environment, the SES itself and a multi channel MDM, which, in turn, enables the MDM to be thoroughly tested by interacting with a faithful simulation of its external environment.