1	LHC Beam Loss Monitor Threshold Comparator Design Considerations: Logging Post Mortem
2	Logging: General Each BLMTC card handles 16 detectors (Ionisation Chambers). From each of these cards two basic sets of information have to be transmitted for the logging purposes: The Threshold & Warning table. (~ 10 KBytes) The measured/calculated data. (< 2 KBytes) The used Th & W values. (< 2 KBytes)
3	Logging: The Threshold & Warning table This table holds the threshold and warning data needed for the comparison with the measured values. They are detector specific (i.e. each card will hold different data) ~ 10 KBytes their values are not foreseen to change often, thus it is not read on regular intervals, only when flagged.
4	Logging: Calculated data & used Th & W values These data have to be read with a rate of a second in order to be stored in a database as well as give a graphical representation for the control room. The information needed to be stored and displayed include the: CID (card ID) Status bits CRC errors Calculated data (integrals) Threshold values choices of each integral Maximum values of the last second.
5	Logging: Calculated data & used Th & W values (cont.)
6	Post Mortem Two circular buffers 2000 turns of both signals received Integrals of 10 ms Double the above system and toggle between them using the stop PM recording trigger Never stop recording (i.e. avoid start input) Test of PM will be possible anytime Accidental/error-triggering proof Calculations: 2000 turns * ~200 bits frame => ~ 50 KB/signal * 2 signals/card = 100 KB /card => 100KB/card * 18 cards/crate = 1.75 MB /crate