STEREO/HET/SIT Configuration Tracking Form

To be filled in by configuration manager:

Tracking Number: 00023 Date Received:   08/23/04

To be filled in by initiator:

Software Type:   Flight Software Instrument Name:   SIT

Version Name: 20040818       Type of Action:   Problem Report  (PR)

Initiator's Name: Peter Walpole                 Date Initiated: 08/03/04

To be filled in by initiator:

Description of action(s)/problems(s):

1. "Spare" event packet could not be read by GSE. 
2. HV ramp down exhibited bizarre behavior when high voltage reached zero.
3. Buffering of sample events was not working as designed
   

To be filled in by Programmer:

Software Version Name:    SIT_FSW_20040903  (Build 1.2)

Programmer(s) Name:   Tom Nolan, K.Wortman

Date Completed:     09/03/04

Modules/Routines affected:   

Comments:  

1.  The "spare" event packet is not part of the flight specification. It allows greater event throughput than flight mode when SIT is being operated in a standalone environment. The number of events was not being placed in the correct location, and a number of empty packets were being inserted.  Solution: modify formatting software.
2. The HV Ramp was not part of the original software specification. A new instrument command was added to automate the process of commanding the high voltage to a new value through a series of uniform steps.  It is expected to be used in flight.  The problem occurred when certain starting high voltage values caused the software to fail the check for when the ramp-down reached the target.  Solution: when ramping down, check to make sure the next step does not take the next HV setting below zero volts.
3. The  overwrite flag and the maximum number of events was not being checked correctly before overwriting the beginning of the buffer, however, this does not explain the 0's in the packet. Apparently,  this was  a side effect from  problem 1 (described above).