Our housekeeping can be operated in a stripchart mode, in which complete housekeeping data is dumped to Science Data RAM at regular intervals. This mode is controlled by serial commands SC31 and SC32. It will be used during testing (both on the ground and in orbit), during initial orbital operations, and during door opening. During normal CCD data collection, stripchart frames are interspersed with CCD frames in the science data.
Stripchart HK Frames have a very simple format. A 64 bit header consists of a 32-bit ID word (defined in Table 28) and the 32-bit satellite time at which the data were recorded. This header is followed by 100 16-bit words containing the 12-bit housekeeping values for HK channels HK1 -- HK100. The next two bytes contain the status bytes BL1 and BL2. Finally, the three time words used to create the satellite time are appended (primarily for debugging purposes). Thus, one Stripchart HK Frame is 216 bytes long. The Stripchart HK Frame format is given in Table 37.
Table 37: Stripchart Mode HK Frame Format