PACS Data Flow 1

PACS IBDR 27/28 Feb 2002

PACS Data Flow, Instrument Modes and Operations

Helmut FeuchtgruberMPE

PACS Data Flow 2

PACS IBDR 27/28 Feb 2002

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

PACS Data Flow 3

PACS IBDR 27/28 Feb 2002

Data FlowData Flow

Blue arrows : TC/SCI/HKGreen arrows : TC/HKRed lines : powerBlack : 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

PACS Data Flow 4

PACS IBDR 27/28 Feb 2002

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

PACS Data Flow 5

PACS IBDR 27/28 Feb 2002

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.

PACS Data Flow 6

PACS IBDR 27/28 Feb 2002

Operating Modes

Blue boxes represent nominal modes

Preferred Mode for “non-prime”

Only used for “mixed” operational days

PACS Data Flow 7

PACS IBDR 27/28 Feb 2002

Observing ModesObserving Modes

Calibration Measurement

LineSpectroscopy

Single-BandPhotometry

RangeSpectroscopy

Dual-BandPhotometry

Dual-BandPhotometry

Single-BandPhotometryPrime Parallel

ObservingMode

Curing

PACS Data Flow 8

PACS IBDR 27/28 Feb 2002

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

PACS Data Flow 9

PACS IBDR 27/28 Feb 2002

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

PACS Data Flow 10

PACS IBDR 27/28 Feb 2002

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

PACS Data Flow 11

PACS IBDR 27/28 Feb 2002

Non-health critical HK Parameter out of Limit

Relative time HK parameter value

DPU action CDMU action

t0 nominal nominal nominal

t1 out of limit issue event analyse event

t1 + t(few sec) 

out of limit execute the OBCP triggered by the CDMUTC for transit into SAFE mode.

disable TCs to PACS from MTL, issue eventand send TC to triggera PACS OBCP (runningin the DPU) to enter PACS SAFE mode.

t2 out of limit or off

SAFE mode check that PACS is in SAFE mode and reportthis by an event.

t2 + t off off nominal

PACS Data Flow 12

PACS IBDR 27/28 Feb 2002

Relative time HK parameter value

DPU action CDMU action

t0 nominal nominal nominal

t1 out of limit issue event analyse event

t1 + t(few sec) 

out of limit start autonomy function inside the DPU

disable TCs to PACS from MTL, issue event

t2 nominal issue event, that PACS is ready with recovery

analyse event

t2 + t(few sec) nominal nominal issue event that PACS is ready to observe again

t3 nominal nominal enable TCs to PACS fromMTL at the next start of a PACS observation (=t3)

t4 nominal nominal nominal

 

Regular Non-Critical Failure

PACS Data Flow 13

PACS IBDR 27/28 Feb 2002

 

Failures which can be detected by CDMU only

Relative time HK parameter value

DPU action CDMU action

t0 nominal nominal nominal

t1 nominal nominal issue OOL event based on S/C powered sensor related to PACS

t1 + t(few sec) 

nominal nominal disable TCs to PACS fromMTL and start with nominal switch-off OBCP(running on the CDMU) for PACS

t2 off off check that PACS is off and issue event

t3 off off nominal, but the sensor(s) in question may still be OOL.