User manual
MEX ASPERA-3
Ref.:
ME-ASP-MA-0002
Issue:
Issue 1 Rev. 4
Date:
15/2/2002
Page:
Page 17 of 58
ASPERA-3 EGSE User Manual
IFSI
CNR
2.4.2.1 SCOE
The SCOE program is the main EGSE interface. The program consists of an editor-like window used
to type, edit and send commands to MEXILT. Commands (one line per command) can be sent one by
one, or as a sequence at a defined time interval.
Instructions can’t be used inside a command file transmitted directly as with TXFILE command.
ASPERA 3 telemetry packets received by MEXILT can be displayed in tabular mode, and the
housekeeping packets are displayed in appropriate windows.
All ASPERA 3 telemetry packets can be stored in the archive directory for the SDM elaboration.
2.4.2.2 MEXILT
MEXILT program simulate the MEX spacecraft and is responsible to deliver to ASPERA the
telecommands received by SCOE and to deliver to SCOE the telemetry received by ASPERA
.
MEXILT program consists of 3 concurrent threads:
• A thread responsible of TCP/IP communications with SCOE
• A thread responsible of continuous telemetry monitoring
• An execution thread interpreting and executing the SCOE commands
Commands received from SCOE are coded as a "packet" with:
• Word 1 = ID identify the command
• Word 2 = N number of words to follow
• Word 3 = Data parameters (if any)
• . . . . . . . . . . . . . . . . . .
• Word N+2= Last parameter
The commands received from SCOE are divided in 3 types, defining the execution priority from high to
low.
The commands are stored in 3 different circular buffers
• Immediate commands
• Program commands
• Normal commands
Generally each command can belong to each of the 3 types.
Immediate commands are executed at the end of the current command execution phase.
Program commands are commands executed as a sequence. The sequence (i.e. the program) is formed
by standard commands plus a few "pseudo instructions" special commands, defining elementary
programming language statements (i.e. for loop, if statements, setting of program variables etc).
Normal commands are executed when no other command type is present.