1. PACS IBDR 27/28 Feb 2002 PACS Data Flow1 PACS Data Flow, Instrument Modes and Operations Helmut Feuchtgruber MPE

2. PACS IBDR 27/28 Feb 2002 PACS Data Flow2 TM/TC Constraints Nominal TM + TC constraints from IID-A and IID-B –Raw data rate of 1.6 Mbit/s in photometry and 3.6 Mbit/s in spectroscopy require flexible compression+reduction schemes –Prime nom. ~120 kbit/s pure science TM, average over 24 h –Prime burst ~300 kbit/s pure science TM for up to 30 min. –50 bit/s TC, average over 24 hours –PACS has a total of ~170 commands and >40 OBCPs –The total amount of HK TM is of the order of 7000 bits

3. PACS IBDR 27/28 Feb 2002 PACS Data Flow3 Data Flow Blue arrows: TC/SCI/HK Green arrows: TC/HK Red lines: power Black : analog lines - 5 commandable units - 6 interfaces - ~27 Mbytes memory (PROM,EEPROM,PRAM,DRAM) - Virtuoso RTOS - 2 different detection systems - Autonomous operation - Uplink bandwidth limit - Downlink bandwidth limit - Redundant units MTL

4. PACS IBDR 27/28 Feb 2002 PACS Data Flow4 Commanding Concept (1) The commanding concept adheres to the PS-ICD for the CDMU-DPU interface All mandatory services are implemented within the DPU OBSW, as well as “Functions” and “OBCPs” The protocol, data rates and data formats between the individual sub-units are described in the respective ICDs: BOLC-DMC, DMC-DPU, DMC-SPU and SPU-DPU The sole repository for all TC and HK definitions is the MIB (SCOS2000) and is currently under completion

5. PACS IBDR 27/28 Feb 2002 PACS Data Flow5 Commanding Concept (2) “Single” commands correspond to service (8,4) requests = “Perform Activity of a Function” Separate Functions are defined for each sub-unit For bandwidth and synchronization reasons a number of OBCPs are and will be defined DMC sequences, stored in the DPU and transferred on request to DMC are used to manage the required highly accurate synchronization of the mechanisms with the acquisition of detector readouts.

6. PACS IBDR 27/28 Feb 2002 PACS Data Flow6 Operating Modes Blue boxes represent nominal modes Preferred Mode for “non-prime” Only used for “mixed” operational days

7. PACS IBDR 27/28 Feb 2002 PACS Data Flow7 Observing Modes Calibration Measurement Line Spectroscopy Single-Band Photometry Range Spectroscopy Dual-Band Photometry Dual-Band Photometry Single-Band Photometry PrimeParallel Observing Mode Curing

8. PACS IBDR 27/28 Feb 2002 PACS Data Flow8 Autonomy Concept (1) Operational days with only ~3h ground contact MTL operation 3 hierarchical levels of autonomy –DPU –Spacecraft –Ground DPU monitors all PACS HK parameters at a rate of 0.5 Hz CDMU needs to react to events and may also need to monitor certain Spacecraft and/or PACS HK parameters

9. PACS IBDR 27/28 Feb 2002 PACS Data Flow9 Autonomy Concept (2) Reporting of anomalies by events, service 5 from DPU to CDMU Events raised by DPU may or may not trigger CDMU activities All unexpected anomalies lead to SAFE or OFF mode and will require ground investigations Expected anomalies may be cured by coordinated procedures between CDMU and DPU

10. PACS IBDR 27/28 Feb 2002 PACS Data Flow10 Autonomy Concept (3) Type of anomalies: –Non-health critical HK parameter OOL   transit to SAFE mode –Health-critical HK parameter OOL  transit to OFF mode –Health-Critical HK parameter OOL monitored by CDMU  transit to OFF mode –Regular non-critical failure   execute curing procedure –Failure related to PACS which can be detected by CDMU only   transit to OFF mode –Failures in other sub-systems of the spacecraft  disable MTL for a while and continue with the next observation

11. PACS IBDR 27/28 Feb 2002 PACS Data Flow11 Non-health critical HK Parameter out of Limit Relative timeHK parameter value DPU actionCDMU action t0t0 nominal t1t1 out of limitissue eventanalyse event t 1 +  t(  few sec) out of limitexecute the OBCP triggered by the CDMU TC for transit into SAFE mode. disable TCs to PACS from MTL, issue event and send TC to trigger a PACS OBCP (running in the DPU) to enter PACS SAFE mode. t2t2 out of limit or off SAFE modecheck that PACS is in SAFE mode and report this by an event. t 2 +  t off nominal

12. PACS IBDR 27/28 Feb 2002 PACS Data Flow12 Relative timeHK parameter value DPU actionCDMU action t0t0 nominal t1t1 out of limitissue eventanalyse event t 1 +  t(  few sec) out of limitstart autonomy function inside the DPU disable TCs to PACS from MTL, issue event t2t2 nominalissue event, that PACS is ready with recovery analyse event t 2 +  t(  few sec) nominal issue event that PACS is ready to observe again t3t3 nominal enable TCs to PACS from MTL at the next start of a PACS observation (=t 3 ) t4t4 nominal Regular Non-Critical Failure

13. PACS IBDR 27/28 Feb 2002 PACS Data Flow13 Failures which can be detected by CDMU only Relative timeHK parameter value DPU actionCDMU action t0t0 nominal t1t1 issue OOL event based on S/C powered sensor related to PACS t 1 +  t(  few sec) nominal disable TCs to PACS from MTL and start with nominal switch-off OBCP (running on the CDMU) for PACS t2t2 off check that PACS is off and issue event t3t3 off nominal, but the sensor(s) in question may still be OOL.