Data Acquisition System Requirements Document (DRD)

h44328 s 03045/00000/00000 d D 1.1 00/06/19 11:26:13 russellg 1 0 c date and time created 00/06/19 11:26:13 by russellg e u U f e 0 t T I 1 Data Acquisition System Requirements Document (DRD)

Data Acquisition System Requirements Document

Release Basic

April 24, 2000

DAQ Requirements Document Committee:

R. Dubois

G. Haller

M. Lovellette

S. Ritz, Co-Chair

J. Russell

S. Williams

R. Williamson, Co-Chair

K. Wood

Subsystem Managers:

Calorimeter, N. Johnson

Tracker, R. Johnson

Anti-Coincidence Detector, J. Ormes

Data Acquisition System, R. Williamson

1 Introduction *

1.1 Purpose
*
1.2 Guidelines
*
1.3 Scope
*
1.4 Applicable Documents
*
1.5 Overview
*
2 Trigger Requirements
*
3 Event Data Flow Requirements
*
3.1 Event Flow Rate
*
3.2 DAQ Contribution to Dead Time
*
3.3 Anti-Coincidence Detector (ACD) Event Data
*
3.3.1 ACD Veto Word Readout *

3.3.2 ACD CNO Word Readout *

3.3.3 ACD PHA Readout *

3.3.4 ACD Readout Modes *

3.3.4.1 ACD Zero Suppressed Mode *

3.3.4.2 ACD Calibration Modes *

3.3.4.2.1 ACD Sampled, Calibration Mode *

3.3.4.2.2 ACD Continuous, Calibration Mode *

3.3.4.3 ACD Nominal Mode *

3.3.5 ACD Average Event Size *

3.3.6 ACD Zero Suppressed Word Size *

3.4 Calorimeter (CAL) Event Data *

3.4.1 Multiple Word Formats *

3.4.1.1 Zero Suppressed Word Format *

3.4.1.1.1 Zero Suppressed Format Word Size *

3.4.1.1.2 Zero Suppressed Format Number of Words *

3.4.1.2 Extended Word Format *

3.4.1.2.1 Extended Word Format Size *

3.4.1.2.2 Extended Word Format Number of Words *

3.4.2 CAL Single and 4 Gain Readout *

3.4.2.1 Single Gain Readout *

3.4.2.1.1 Fixed Gain, Single Gain Readout *

3.4.2.1.2 Autorange, Single Gain Readout *

3.4.2.2 Four Gain Readout *

3.4.3 CAL Readout Modes *

3.4.3.1 Nominal Mode Readout *

3.4.3.1.1 Nominal Mode, Single Gain Readout *

3.4.3.1.2 Nominal Mode, 4 Gain Readout *

3.4.3.2 Calibration Mode Readout *

3.4.3.2.1 Calibration Mode Autorange Readout *

3.4.3.2.2 Calibration Mode 4 Gain Readout *

3.4.3.2.3 Calibration Mode 4 Gain, Zero Suppressed Readout *

3.4.4 CAL Zero Suppressed Average Event Size *

3.4.5 CAL Zero Suppressed Worst Case Event Size *

3.5 Tracker (TKR) Event Data *

3.5.1 TKR Dual Readout *

3.5.2 TKR Single Cable Readout *

3.5.3 TKR Front End Buffering *

3.5.4 TKR Word Formats *

3.5.4.1 TKR Header Word *

3.5.4.2 TKR Time Over Threshold Word *

3.5.4.3 TKR Hit Address Word *

3.5.4.4 TKR CRC Word *

3.5.5 TKR Readout Formats *

3.5.5.1 Nominal Readout Mode *

3.5.5.2 CRC Readout Mode *

3.5.6 TKR Average Event Size *

3.6 Trigger (L1T) Event Data *

3.7 Event Data Bit Rates *

3.7.1 ACD Maximum Discriminator Data Rate Output *

3.7.2 ACD Average PHA Data Rate Output *

3.7.3 ACD Maximum PHA Data Rate Output *

3.7.4 CAL Average Data Rate Output *

3.7.5 CAL Maximum Data Rate Output *

3.7.6 TKR Average Data Rate Output *

3.7.7 TKR Maximum Data Rate Output *

3.7.8 L1T Data Rate Output *

4 Science Housekeeping Requirements *

4.1 ACD Rate Counters *

4.1.1 ACD Rate Counter Word *

4.1.2 ACD Discriminator Rate Counters *

4.1.3 ACD Supertile Rate Counters *

4.1.4 ACD Zone Rate Counters *

4.2 CAL Rate Counters *

4.2.1 CAL Rate Counter Word *

4.2.2 CAL Discriminator Rate Counters *

4.3 TKR Rate Counters *

4.4 Science Housekeeping Readout Rate *

4.5 Science Housekeeping Sample Rate Range *

4.6 Rate Counter Readout Synchronization *

4.7 Science Housekeeping Bit Rate *

4.7.1 ACD Rate Counter Maximum Bit Rate *

4.7.2 ACD Rate Counter Average Bit Rate *

4.7.3 ACD Zone Counter Maximum Bit Rate *

4.7.4 CAL Rate Counter Maximum Bit Rate *

4.7.5 CAL Rate Counter Average Bit Rate *

4.7.6 TKR Rate Counter Maximum Bit Rate *

4.7.7 TKR Rate Counter Average Bit Rate *

5 Command and Messaging Requirements *

5.1 CCSDS Command and Data Format *

5.2 1553B Command Services Supported *

5.3 SI Command/Response Data *

5.3.1 Housekeeping Data from the DAQ *

5.3.2 Time Distribution to DAQ *

5.3.3 Ancillary Data To DAQ *

5.3.3.1 Attitude *

5.3.3.2 Orbit Position Vector *

5.3.3.3 Observation ID *

5.3.4 Ancillary Data Downlink *

5.4 Observatory Pointing Commands *

5.4.1 Transient Event Control *

5.5 Transient Alert Message *

5.5.1 Transient Message Type *

5.5.2 Transient Message Coordinates *

5.5.3 Transient Message Timestamp *

5.5.4 Transient Message Quality Factor *

5.5.5 Transient Message Sequence Number *

5.5.6 Transient Message Revision Number *

5.5.7 Transient Message Variable Text *

5.5.8 Transient Message Latency *

5.6 Hardware Commands *

5.6.1 ACD Hardware Commands *

5.6.2 CAL Hardware Commands *

5.6.3 TKR Hardware Commands *

5.6.4 DAQ Hardware Commands *

5.7 DAQ Software Loads Command *

5.8 DAQ Memory Dump Command *

5.9 Command Verification *

5.10 Configuration State Commands *

5.10.1 Configuration State Table *

5.10.2 Configuration State Table Updates *

5.10.3 Configuration State Initialization *

5.10.4 Command Configuration Verification *

5.11 Command Acknowledgement *

5.11.1 Command Counter *

5.11.1.1 Receive Command Counter *

5.11.1.2 Execute Command Counter *

5.11.1.3 Reject Command Counter *

5.11.2 Command Copy *

5.11.3 Command Timestamp *

5.11.4 Command Verification *

5.11.5 Command Acknowledgement Packet (CAP) *

5.11.5.1 CAP Command Counter *

5.11.5.2 CAP Timestamp *

5.11.5.3 CAP Command Echo *

5.11.5.4 CAP Command Verification *

5.11.5.5 CAP Checksum *

5.11.6 CAP Transmission *

5.12 Operating Modes *

5.12.1 Initialization Mode *

5.12.2 Checkout Mode *

5.12.3 Calibration Mode *

5.12.4 Test Mode *

5.12.5 Pointed Mode *

5.12.6 Level 1 Trigger Modes *

5.12.7 Level 2 and Level 3 Trigger Modes *

5.12.8 Power Constrained Mode *

5.12.9 Time Dependent Event Mode *

5.12.9.1 Gamma-Ray Bursts (GRB) *

5.12.9.1.1 Peak GRB trigger rate *

5.12.9.1.2 GRB detection *

5.12.9.1.3 GRB alert message *

5.12.9.1.4 GRB Dead Time *

5.12.9.2 Active Galactic Nuclei *

5.12.9.3 Solar flares *

5.12.10 South Atlantic Anomaly Environment *

5.12.10.1 SAA Detection *

5.12.10.2 SAA Calculation *

5.12.10.3 SAA Mode *

6 Instrument Health Housekeeping Requirements *

6.1 Temperature monitors *

6.1.1 ACD Temperature Monitors *

6.1.2 CAL Temperature Monitors *

6.1.3 TKR Temperature Monitors *

6.1.4 DAQ Temperature Monitors *

6.1.4.1 Power Supply Temperature Monitors *

6.1.4.2 Electronics Board Temperature Monitors *

6.1.4.3 Grid Temperature Monitors *

6.2 Input Voltage Monitors *

6.3 Output Voltage Monitors *

6.4 Input Current Monitor *

6.5 Power Supply Current Monitors *

6.6 Strain gauges *

7 Appendix A: Requirements Traceability Matrix *

8 Appendix B: Requirements Justification Matrix *

9 Appendix C: Requirements Verification Matrix *

10 Appendix D: Nomenclature and Abbreviations *

Introduction

Purpose

The purpose of this document is to establish the top-level requirements for the data acquisition system of the GLAST instrument.

Guidelines

Requirements should be established independent of implementation considerations, such as whether a function is performed in hardware or software. Similarly, ignore presently planned functional and organizational partitions. For example, even though the tracker subsystem captures and stores discriminator triggers for readout by the DAQ, this storage and readout process should be regarded as part of the DAQ functionality. The proper functional interface is at the output of the discriminator, which can be defined in terms of incident flux and analog properties of the detector/amplifier/discriminator signal processing chain. Requirements on individual pieces of the DAQ (hardware or software) will be derived later from the requirements established in this document.

Scope

The scope of this document is the event data flow, housekeeping, and commanding for the data acquisition system. The requirements for triggers, power supplies, electrical interfaces, and command interface to the spacecraft will be established in separate documents.

Applicable Documents

Science Requirements Document (July 9, 1999)

http://glast.gsfc.nasa.gov/SRD

Space Instrument to Spacecraft Interface Requirements Document (August 3, 1999)

http://glast.gsfc.nasa.gov/ao/SI-SC_IRDv.3.pdf

GLAST Large Area Telescope Flight Investigation: An Astro-Particle Physics Partnership Exploring the High-Energy Universe, Volume 1: Technical Plan, Proposal, November 1999, Stanford University.

ACD DAQ Requirements, March, 2000,

http://giants.stanford.edu/daq/docs/requirements/DAQRD/ACD_DAQ_Requirements.pdf

CAL DAQ Requirements, March, 2000

http://giants.stanford.edu/daq/docs/requirements/DAQRD/CAL_DAQ_Requirements.pdf

Science DAQ Requirements V1.3, March, 2000

http://giants.stanford.edu/daq/docs/requirements/DAQRD/ScienceDAQRequirementsV1.3.pdf

HSK DAQ Requirements March, 2000

http://giants.stanford.edu/daq/docs/requirements/DAQRD/HSK_DAQ_Requirements.pdf

TKR-EventDataFlow

http://giants.stanford.edu/daq/docs/requirements/DAQRD/TKR_EventDataFlow.pdf

Overview

The DAQ provides the trigger, read out, onboard processing, command, telemetry, and control of the GLAST instrument. In order to establish the high level requirements on the data acquisition system, this document addresses specifically only those top level requirements in support of the detector read outs and commanding of the instrument. The remaining requirements will be documented elsewhere.

Throughout this document, reference is made to the instrument or to a detector module. The Instrument refers to the sum of all detector modules where there are 16 CAL modules and 16 TKR modules. Average event sizes are computed by summing all events over an orbit and dividing by the number of events. Average rates refer to orbit averages, and orbit maximum refers to the peak L1T rate, which occurs when the observatory is at the orbit location corresponding to maximum cosmic ray flux.

Trigger Requirements

Trigger requirements on the DAQ shall be as specified in the DAQ Trigger Requirements Document.

Event Data Flow Requirements

The DAQ shall read out the ACD, CAL, and TKR detector and Level 1 Trigger event data.

Event Flow Rate

The DAQ shall read out the event data at a rate determined by the Level 1 Trigger.

DAQ Contribution to Dead Time

The DAQ readout shall not increase the dead time of the instrument more than 5% when the L1T rate is at maximum L1T rate nor more than 1% when the L1T rate is 60% of maximum.

Anti-Coincidence Detector (ACD) Event Data

The DAQ shall read out the ACD event data assuming the ACD configuration consists of 2 sets of 145 PMTs reading out 145 tiles, where each tile is readout by a redundant pair of PMTs. The PMT outputs are fed to low (Veto) threshold discriminators, and a subset of 65 (TBR) PMT outputs from the top tiles and first row of side tiles are also fed to high level discriminators to detect high ionizing cosmic rays (CNO). The veto discriminator outputs are formed into supertile groups with one supertile associated with each tower. A second grouping of 5 zones (TBR) is formed with one zone for the top tiles and one zone for each of the 4 sides. The zone groups would be rate counted in order to identify transient events.

ACD Veto Word Readout

The DAQ shall read out a redundant, 145(TBR) bit ACD Low (Veto) for a total of 290(TBR) bits for each event.

ACD CNO Word Readout

The DAQ shall read out a redundant (TBR), 65(TBR) bit ACD CNO word for a total of 130(TBR) bits for each event.

ACD PHA Readout

The DAQ shall be able to readout the 12 bit PHA, a 9 bit address and a 1 bit range indicator.

ACD Readout Modes

The DAQ shall readout the ACD in 3 modes in addition to the continuous readout of the ACD Veto Word and the ACD CNO Word.

ACD Zero Suppressed Mode

In Zero Suppressed Mode, the DAQ shall readout the ACD PHA in zero suppressed format from all tiles above an internally set threshold.

ACD Calibration Modes

The DAQ shall readout the ACD PHA in two calibration modes.

ACD Sampled, Calibration Mode

In ACD Sampled, Calibration Mode, the DAQ shall perform PHA readout from all active PMT channels once every 16 (TBR) seconds.

ACD Continuous, Calibration Mode

In Continuous, Calibration Mode, the DAQ shall perform PHA readout from all active PMT channels every event for a total of 1000 (TBR) events at the L1T rate.

ACD Nominal Mode

In Nominal Mode, the DAQ shall readout the ACD PHA using ACD Sampled, Calibration Mode.

ACD Average Event Size

The DAQ shall assume an average of 10(TBR) tiles PHA information per event.

ACD Zero Suppressed Word Size

The DAQ shall readout the ACD assuming a 22 bit word size for each tile with 9 bits of channel address, 12 bits of ADC output per PMT, and 1 bit of scale.

Calorimeter (CAL) Event Data

The DAQ shall readout the CAL event data assuming 16 CAL modules composed of 96 logs with 2 ends for a total of 192 log ends per module and 3072 log ends for the instrument. Each log end has 4 gain channels for a total of 768 gain channels per module and 12288 for the instrument.

Multiple Word Formats

The DAQ shall read out the CAL event data in 2(TBR) word formats depending on the commanded state.

Zero Suppressed Word Format

The DAQ shall be capable of reading out the CAL with a zero suppressed word format.

Zero Suppressed Format Word Size

In Zero Suppressed format, the DAQ shall readout in a 22 (TBR) bits per log end format (or 44 bits per log.).

Zero Suppressed Format Number of Words

The DAQ shall readout a variable length list of crystal IDs, pulse height measurements, and gain ranges of up to (3072) Zero Suppressed words with the end of the list terminated by a special termination word in each CAL module (+16=3088 words.)

Extended Word Format

Extended Word Format Size

In Extended Mode, the DAQ shall readout in a 16(TBR) bit word format.

Extended Word Format Number of Words

In Extended Format, the DAQ shall readout each end of all logs in a fixed sequence, which does not require address, bits.

CAL Single and 4 Gain Readout

The DAQ shall readout the CAL in either single or 4 gain format.

Single Gain Readout

The DAQ shall provide for CAL readout of a single gain.

Fixed Gain, Single Gain Readout

In Fixed Gain, Single Gain Readout, the DAQ shall readout a single, commanded gain range from the CAL.

Autorange, Single Gain Readout

In Autorange, Single Gain Readout, the DAQ shall readout a single gain range which is auto-selected by the CAL.

Four Gain Readout

The DAQ shall provide for CAL sequential readout of all 4 gain ranges in any order.

CAL Readout Modes

The DAQ shall readout the CAL in 5(TBR) modes.

Nominal Mode Readout

In Nominal Readout Mode, the DAQ shall readout the CAL using a Zero Suppressed word format with a combination of Single and 4 Gain range readouts.

Nominal Mode, Single Gain Readout

In Nominal Mode, the DAQ shall readout the CAL using Zero Suppressed Word Format in an Autorange, Single Gain mode.

Nominal Mode, 4 Gain Readout

In Nominal Mode, the DAQ shall in addition to the Single Gain mode readout, also support a readout in Zero Suppressed, 4 Gain Readout mode which is triggered by a pre-scaled ACD (CNO) prescaled trigger signal.

Calibration Mode Readout

In Calibration Mode, the DAQ shall readout the CAL in 3(TBR) modes.

Calibration Mode Autorange Readout

In the Calibration Autorange mode, the DAQ shall readout one autoranged channel of each log end for the CAL using the Extended Word Format.

Calibration Mode 4 Gain Readout

In the Calibration 4 Gain mode, the DAQ shall readout 4 channels for each log end of the CAL using the Extended Word Format.

Calibration Mode 4 Gain, Zero Suppressed Readout

In the Calibration 4 Gain, Zero Suppressed readout mode, the DAQ shall readout each gain range of each log end of the CAL using the Zero Suppressed Word Format.

CAL Zero Suppressed Average Event Size

The DAQ shall at a minimum be able to readout continuously the Instrument Average, Zero Suppressed CAL event data of 38 logs (2ends*38logs=76 words) per event.

CAL Zero Suppressed Worst Case Event Size

The DAQ shall be able to readout all log ends simultaneously in the Nominal CAL mode at the L1T maximum rate (i.e., (38logs*2ends+16(TBR) terminator words)*10kHz*22(TBR) bits/word = 20 Mbps instrument average.)

Tracker (TKR) Event Data

The DAQ shall readout the TKR in two modes and assume a TKR layout as follows: 16 tracker modules, each with 18 x,y planes (TBR), or 36 layers, and each layer with 1792 channels (TBR). Each module is divided into 4 sides, with each side being at least one independent readout. Each layer has 28 front end ASICs (GTFE) with 64 channels per ASIC. Controllers on each end are limited to 63 (TBR) hit addresses in any given event. Therefore, each TKR module is designed to handle 36 layers*2 controllers *63 hits = 4536 hits per event per module or 72576 hits for the instrument total. The TKR readout word sizes and bit rates are referred to the 4sides*2cables/side=8cables which interface the TKR hybrid mounted electronics to the DAQ.

TKR Dual Readout

The DAQ shall readout each layer of the TKR from a dual cable interface with the split between GTFE ASICs within any layer determined by command.

TKR Single Cable Readout

Upon command, the DAQ shall be able to readout an entire layer through either one of the dual readout cables.

TKR Front End Buffering

The DAQ readout of the tracker shall have sufficient event buffering at the front end that dead time due to readout becomes significant (>1%) only when the readout bandwidth is saturated. This implies that it must be possible to keep the tracker trigger live during readout.

TKR Word Formats

The DAQ shall readout 4 different word types from the TKR.

TKR Header Word

The DAQ shall readout a header word which identifies the layer and number of hits in the layer.

TKR Time Over Threshold Word

The DAQ shall readout an 11 bit Time Over Threshold (TOT) word.

TKR Hit Address Word

The DAQ shall readout an 11 bit hit address.

TKR CRC Word

The DAQ shall readout an 11 bit CRC computed on the total of all words from the layer for a given event.

TKR Readout Formats

The DAQ shall readout the TKR in 2 commandable readout formats.

Nominal Readout Mode

In TKR Nominal Readout Mode, the DAQ shall expect a TKR Header word from each GTRC (layer controller), a TOT word, and up to 63(TBR) TKR Hit Address words.

CRC Readout Mode

In CRC Readout Mode, the DAQ shall expect the same sequence of words as in Nominal Readout mode plus an additional TKR CRC word as the last word transmitted by the controller.

TKR Average Event Size

The DAQ shall readout the TKR assuming an average event size of 196 hits orbit average and 226 hits orbit maximum with an average of 65 (TBR) bits per hit. The bits are calculated assuming 1 start bit followed by four 11 bit words: address (5) + number of hits (6), one hit address (11), TOT (10) + error flag (1), and CRC (11)(TBR).

Trigger (L1T) Event Data

The DAQ shall readout the Level 1 Trigger event data of 300 (TBR) bytes instrument total per event.

Event Data Bit Rates

The DAQ shall readout events at a rate determined by the average and maximum L1T rates and the readout mode of each element.

ACD Maximum Discriminator Data Rate Output

The DAQ shall readout the ACD event data at a rate of at least 1.9 (TBR) Mbps assuming 190(TBR) bits per event total for Veto (145 bits) and CNO (65 TBR) discriminator output at the maximum L1T rate of 10 kHz.

ACD Average PHA Data Rate Output

The DAQ shall readout the ACD PHA at an orbit averaged bit rate of at least 5.5kHz*(9address+12ADC)*12tiles/event=1.4 Mbps.

ACD Maximum PHA Data Rate Output

The DAQ shall readout the ACD PHA at an orbit maximum bit rate of at least 10kHz*(9address+12ADC)*12tiles/event=2.5 Mbps.

CAL Average Data Rate Output

The DAQ shall readout the CAL at an orbit averaged bit rate of at least 6(TBR) Mbps.

CAL Maximum Data Rate Output

The DAQ shall readout the CAL at a minimum, sustained bit rate of 20 15 (TBR) Mbps.

TKR Average Data Rate Output

The DAQ shall readout the total instrument TKR at an orbit average rate of 49 Mbps (49Mbps/16modules=3 Mbps/module) assuming a noise occupancy of 1e(-4), an average of 196 hits, 45 bits per hit, and an average L1T rate of 5.5 kHz

TKR Maximum Data Rate Output

The DAQ shall provide a minimum sustained readout of each TKR module at a rate of 6.4 Mbps or 102 Mbps instrument total assuming an average number of hits per event of 226 and 45 bits per hit at maximum L1T rate of 10 kHz.

L1T Data Rate Output

The DAQ shall readout the Level 1 Trigger event data at a rate of at least 300bytes*10kHz*8bits=24(TBR) Mbps.

Science Housekeeping Requirements

The DAQ shall readout and reset to zero rate counters for monitoring the singles rates of each of the detector modules.

ACD Rate Counters

The DAQ shall readout 3 rate counter types from the ACD.

ACD Rate Counter Word

The DAQ shall readout the ACD rate counters as a 16(TBR) bit word.

ACD Discriminator Rate Counters

The DAQ shall read out a rate counter for each of the 2redundant*145=290 (TBR) Veto discriminator outputs and 2redundant*65=130(TBR) CNO discriminator outputs of the ACD.

ACD Supertile Rate Counters

The DAQ shall read out an ACD rate counter for each of the 16 Supertiles.

ACD Zone Rate Counters

The DAQ shall readout an ACD rate counter for each of the 5 zones of the ACD.

CAL Rate Counters

The DAQ shall readout rate counters from each of the 16 CAL modules.

CAL Rate Counter Word

The DAQ shall readout the CAL rate counters as 16 bit words.

CAL Discriminator Rate Counters

The DAQ shall readout 3disc*2ends*96logs=576 diagnostic rate counters for each CAL module or 16towers*576=9216 rate counters for the instrument.

TKR Rate Counters

For each Tracker module, the DAQ shall readout one 16 bit diagnostic rate counter for each TKR layer or 36 rate counters for each TKR module and 16towers*36=576 rate counters for the instrument.

Science Housekeeping Readout Rate

The readout rate for sampling the science housekeeping rate counters shall be programmable.

Science Housekeeping Sample Rate Range

The sampling rate for the science housekeeping readout shall be in the range of 64 (TBR) per second to 64 (TBR) seconds per sample.

Rate Counter Readout Synchronization

The DAQ shall synchronize the readout of all rate counters in the instrument with an average jitter less than 1(TBR) microsecond although different sample rates may be used for each rate counter type.

Science Housekeeping Bit Rate

The DAQ shall have the capability to readout the science rate counters at the maximum sample rate.

ACD Rate Counter Maximum Bit Rate

The DAQ shall have the capability to read out the ACD discriminator and supertile rate counters at a bit rate of 2redundant*(145 veto+65 CNO +16 supertile)*16 bits*16/second=105 kbps.

ACD Rate Counter Average Bit Rate

The DAQ shall have the capability to read out the ACD discriminator and supertile rate counters at a bit rate of 2redundant*(145 veto+65 CNO +16 supertile)*16 bits*1/second= 7 kbps.

ACD Zone Counter Maximum Bit Rate

The DAQ shall be able to readout the 5 ACD zone rate counters at a bit rate of 5counters*16bits*64/sec = 5120 bps.

CAL Rate Counter Maximum Bit Rate

The DAQ shall have the capability to read out the CAL diagnostic rate counters at a bit rate of 16modules*16bits*576counters*1/sec=150kbps(TBR) instrument maximum.

CAL Rate Counter Average Bit Rate

The DAQ shall readout the CAL rate counters at an average bit rate of 16 modules*16 bits*576 counters*1/64seconds=2.3 kbps assuming one sample every 64 seconds.

TKR Rate Counter Maximum Bit Rate

The DAQ shall have the capability to read out the TKR rate counters at a maximum bit rate of 16towers*16bits*36layers*16/sec=144k (TBR) bits per second instrument average.

TKR Rate Counter Average Bit Rate

The DAQ shall readout the TKR rate counters at an instrument average bit rate of 16towers*16bits*36layers= 9216 bits per second assuming one sample per second.

Command and Messaging Requirements

CCSDS Command and Data Format

Commands and telemetry data that are transferred over the command/data bus shall be formatted as CCSDS source packets.

1553B Command Services Supported

The DAQ shall not require segmentation or grouping services.

SI Command/Response Data

This section addresses the specific transactions that coordinate DAQ-SC operations.

Housekeeping Data from the DAQ

The DAQ shall respond to an SC request for an SC defined housekeeping data packet (which will be downlinked in the S-band telemetry stream by the SC) containing parameters and monitor values necessary for SC monitoring of operation and safety.

Time Distribution to DAQ

The DAQ shall receive a time message that gives Universal Coordinated Time (UTC) at the 1 PPS signal. This message will be issued 50 to 100 ms (TBR) prior to the transition of the1 PPS signal.

Ancillary Data To DAQ

The DAQ shall receive ancillary data from the SC.

Attitude

The DAQ shall receive from the SC a time tagged attitude vector from the SC Attitude Control Subsystem (ACS) at the attitude control loop rate of 5 Hz (TBR).

Orbit Position Vector

The DAQ shall receive the SC determined orbit position data.

Observation ID

Other ancillary data, such as observation ids that are generated on the ground, shall be received by the DAQ in the data field of commands sent by the SC.

Ancillary Data Downlink

The DAQ shall include the SC ancillary data received via the command/data bus in the telemetry data stream.

Observatory Pointing Commands

Transient Event Control

When enabled, the DAQ shall transmit a pointing command to the SC.

Transient Alert Message

The DAQ shall be able to generate a Transient Alert Message to the SC for realtime transmission to the ground.

Transient Message Type

The Transient message shall contain a character indicating the type of event detected.

Transient Message Coordinates

The Transient message shall use the J2000 coordinate system to indicate the direction of the Transient.

Transient Message Timestamp

The Transient message shall contain the UTC time of the start of the Transient in units of 1 microseconds.

Transient Message Quality Factor

The Transient message shall contain a Transient Quality Factor which is a measure of the confidence that a Transient has been detected.

Transient Message Sequence Number

The Transient message shall contain an incrementing sequence number which uniquely identifies each event in time.

Transient Message Revision Number

The Transient message shall contain an incrementing revision number which permits changes to be issued in the pointing direction and Quality Factor for the same Sequence Number.

Transient Message Variable Text

The Transient message shall provide for a variable length text of 800(TBR) bytes.

Transient Message Latency

The DAQ shall compute and transmit the Transient message in less than 5 seconds after the detection of the start of an event.

Hardware Commands

The DAQ shall provide hardware commands for the instrument.

ACD Hardware Commands

The DAQ shall provide for hardware commanding of the ACD.

CAL Hardware Commands

The DAQ shall provide for hardware commanding of the CAL.

TKR Hardware Commands

The DAQ shall provide for hardware commanding of the TKR.

DAQ Hardware Commands

The DAQ shall provide for hardware commanding of the DAQ.

DAQ Software Loads Command

The DAQ software shall be re-programmable via software load commands.

DAQ Memory Dump Command

The DAQ shall be able to dump program memory as well as data memory on command.

Command Verification

The DAQ shall provide for non-destructive, hardware command verification for all hardware commands.

Configuration State Commands

The DAQ shall command the configuration state of each detector module.

Configuration State Table

The DAQ shall maintain one or more command configuration tables for each detector module.

Configuration State Table Updates

The DAQ shall maintain a current command configuration table for each detector module.

Configuration State Initialization

The DAQ shall be capable of commanding the state of each detector module using a command configuration table.

Command Configuration Verification

The DAQ shall be capable of non-destructive readout of the current command state of each detector module for comparison with the current command configuration table.

Command Acknowledgement

The DAQ shall acknowledge the receipt of each command.

Command Counter

The DAQ shall increment separate, non-resettable command counters for each processor.

Receive Command Counter

The DAQ shall increment a non-resettable command counter for each command received with one counter for each processor.

Execute Command Counter

The DAQ shall increment a non-resettable command counter for each command executed with one counter for each processor.

Reject Command Counter

The DAQ shall increment a non-resettable command counter for each command rejected with one counter for each processor.

Command Copy

The DAQ shall save a copy of the received command.

Command Timestamp

The DAQ shall generate a timestamp upon the receipt of a command.

Command Verification

The DAQ shall verify the execution of each command.

Command Acknowledgement Packet (CAP)

The DAQ shall generate a command acknowledgement packet for each command received.

CAP Command Counter

The command acknowledgement packet shall include the command counter.

CAP Timestamp

The CAP shall include the command timestamp.

CAP Command Echo

The command acknowledgement packet shall include a copy of the command as received.

CAP Command Verification

The CAP shall include the verification status of each command.

CAP Checksum

The CAP shall include a packet checksum.

CAP Transmission

The CAP shall be transmitted after generation.

Operating Modes

The DAQ shall provide operating modes of the instrument.

Initialization Mode

The DAQ shall provide a mode to support the initialization of the instrument after power on or anytime by command.

Checkout Mode

The DAQ shall provide a checkout mode used to determine the functional status of the instrument.

Calibration Mode

The DAQ shall provide a calibration mode used to calibrate the detector performance, gain, and position.

Test Mode

The DAQ shall provide for multiple test modes dedicated to specific tests.

Pointed Mode

The DAQ shall provide for a pointed mode in which the instrument is pointed at a fixed direction in inertial space.

Level 1 Trigger Modes

The DAQ shall provide commands to configure the Level 1 Trigger.

Level 2 and Level 3 Trigger Modes

The DAQ shall provide commands to configure the higher level software triggers (Level 2 Trigger and Level 3 Trigger.)

Power Constrained Mode

The DAQ shall provide a power constrained mode in which the instrument power is managed by reducing resource usage or scheduling.

Time Dependent Event Mode

The DAQ shall provide modes which support the detection and acquisition of time dependent events.

Gamma-Ray Bursts (GRB)

The DAQ shall provide for the detection and response to a GRB.

Peak GRB trigger rate

The DAQ shall accept a 20 kHz (TBR) additional trigger rate for up to 100(TBR) milliseconds at any time during nominal operation.

GRB detection

The DAQ shall accept a GRB in progress message from the SC or the instrument and initiate a special (TBR) GRB operating mode.

GRB alert message

Open Upon detection by the instrument of a GRB, the DAQ shall generate a Transient Alert Message.

GRB Dead Time

At the peak L1T Trigger Rate, the DAQ shall accept up to 2000 additional photon induced L1T triggers during a transient event within 100(TBR) milliseconds without increasing the dead time by more than 10%(TBR) of the Level 1 Trigger contribution.

Active Galactic Nuclei

The DAQ shall provide a mode to detect, acquire data from, and send a Transient Alert Message for Active Galactic Nuclei events.

Solar flares

The DAQ shall provide a mode to detect, acquire data from, and send a Transient Alert Message for Solar Flares which produce gamma-rays within the GLAST energy range.

South Atlantic Anomaly Environment

The DAQ shall provide a mode to support instrument operation in the SAA environment.

SAA Detection

The DAQ shall provide a means of detecting the entry and exit of the SAA.

SAA Calculation

The DAQ shall be capable of calculating the entry and exit of the SAA on the basis of time.

SAA Mode

When commanded, the DAQ shall place the instrument in a safe and stable configuration during the SAA passage and return the instrument to its previous operating configuration upon exit from the SAA.

Instrument Health Housekeeping Requirements

The DAQ shall provide housekeeping monitors for the instrument.

Temperature monitors

The DAQ shall provide temperature monitors for the instrument.

ACD Temperature Monitors

The DAQ shall monitor the temperature of the ACD at 24(TBR) places.

CAL Temperature Monitors

The DAQ shall monitor the temperature of each CAL at 8 (TBR) places.

TKR Temperature Monitors

The DAQ shall monitor the temperature of each TKR at 8 (TBR) places.

DAQ Temperature Monitors

The DAQ shall monitor the temperature at 16 (TBR) locations within the DAQ and Grid.

Power Supply Temperature Monitors

The DAQ shall monitor the temperature of each power supply.

Electronics Board Temperature Monitors

The DAQ shall monitor the temperature of each electronics board within the DAQ.

Grid Temperature Monitors

The DAQ shall monitor the temperature at 16(TBR) places on the Grid and other structural elements of the instrument external to the DAQ housing.

Input Voltage Monitors

The DAQ shall monitor the input voltage for all power supplies.

Output Voltage Monitors

The DAQ shall monitor the output voltage of all power supplies.

Input Current Monitor

The DAQ shall monitor the input current to the instrument at the SC power bus interface.

Power Supply Current Monitors

The DAQ shall separately monitor the input current to each power supply.

Strain gauges

The DAQ shall provide signal conditioning and sources for monitoring strain gauges at 16 (TBR) places mounted to the SI structure.

Appendix A: Requirements Traceability Matrix

Source Document	Source Requirement ID Identifier
ACD-DAQ Requirements	A
CAL-DAQ Requirements	C
TKR-DAQ Requirements	T
Science DAQ Requirements	S
Space Instrument to Spacecraft Interface Requirements Document	IRD
Science Requirements Document	SRD

DAQRD Section	DAQRD Requirement	Source Requirement ID
3	EVENT DATA FLOW REQUIREMENTS
3.1	Event Flow Rate
3.2	DAQ Contribution to Dead Time
3.3	Anti-Coincidence Detector (ACD) Event Data	A9
3.3.1	ACD Veto Word Readout	A13,A37,A42
3.3.2	ACD CNO Word Readout	A15,A52,A58
3.3.3	ACD PHA Readout	A63
3.3.4	ACD Readout Modes
3.3.4.1	ACD Zero Suppressed Mode
3.3.4.2	ACD Calibration Modes
3.3.4.2.1	ACD Sampled, Calibration Mode
3.3.4.2.2	ACD Continuous, Calibration Mode
3.3.4.3	ACD Nominal Mode
3.3.5	ACD Average Event Size
3.3.6	ACD Zero Suppressed Word Size
3.4	Calorimeter (CAL) Event Data	3.3.1--3.3.10
3.4.1	Multiple Word Formats	C263
3.4.1.1	Zero Suppressed Word Format	C267
3.4.1.1.1	Zero Suppressed Format Word Size	C267
3.4.1.1.2	Zero Suppressed Format Number of Words	C267
3.4.1.2	Extended Word Format	C278
3.4.1.2.1	Extended Word Format Size	C278
3.4.1.2.2	Extended Word Format Number of Words	C278
3.4.2	CAL Single and 4 Gain Readout
3.4.2.1	Single Gain Readout
3.4.2.1.1	Fixed Gain, Single Gain Readout
3.4.2.1.2	Autorange, Single Gain Readout
3.4.2.2	Four Gain Readout
3.4.3	CAL Readout Modes
3.4.3.1	Nominal Mode Readout
3.4.3.1.1	Nominal Mode, Single Gain Readout
3.4.3.1.2	Nominal Mode, 4 Gain Readout
3.4.3.2	Calibration Mode Readout
3.4.3.2.1	Calibration Mode Autorange Readout
3.4.3.2.2	Calibration Mode 4 Gain Readout
3.4.3.2.3	Calibration Mode 4 Gain, Zero Suppressed Readout
3.4.4	CAL Zero Suppressed Average Event Size
3.4.5	CAL Zero Suppressed Worst Case Event Size
3.5	Tracker (TKR) Event Data	3.4.1ù3.4.4
3.5.1	TKR Dual Readout
3.5.2	TKR Single Cable Readout
3.5.3	TKR Front End Buffering
3.5.4	TKR Word Formats
3.5.4.1	TKR Header Word
3.5.4.2	TKR Time Over Threshold Word
3.5.4.3	TKR Hit Address Word
3.5.4.4	TKR CRC Word
3.5.5	TKR Readout Formats
3.5.5.1	Nominal Readout Mode
3.5.5.2	CRC Readout Mode
3.5.6	TKR Average Event Size
3.6	Trigger (L1T) Event Data
3.7	Event Data Bit Rates
3.7.1	ACD Maximum Discriminator Data Rate Output	S366
3.7.2	ACD Average PHA Data Rate Output	S371
3.7.3	ACD Maximum PHA Data Rate Output
3.7.4	CAL Average Data Rate Output	S298
3.7.5	CAL Maximum Data Rate Output	S298
3.7.6	TKR Average Data Rate Output	S352
3.7.7	TKR Maximum Data Rate Output	S352
3.7.8	L1T Data Rate Output	S183
4	SCIENCE HOUSEKEEPING REQUIREMENTS
4.1	ACD Rate Counters
4.1.1	ACD Rate Counter Word
4.1.2	ACD Discriminator Rate Counters
4.1.3	ACD Supertile Rate Counters
4.1.4	ACD Zone Rate Counters
4.2	CAL Rate Counters
4.2.1	CAL Rate Counter Word
4.2.2	CAL Discriminator Rate Counters
4.3	TKR Rate Counters
4.4	Science Housekeeping Readout Rate
4.5	Science Housekeeping Sample Rate Range
4.6	Rate Counter Readout Synchronization
4.7	Science Housekeeping Bit Rate
4.7.1	ACD Rate Counter Maximum Bit Rate
4.7.2	ACD Rate Counter Average Bit Rate
4.7.3	ACD Zone Counter Maximum Bit Rate
4.7.4	CAL Rate Counter Maximum Bit Rate
4.7.5	CAL Rate Counter Average Bit Rate
4.7.6	TKR Rate Counter Maximum Bit Rate
4.7.7	TKR Rate Counter Average Bit Rate
5	COMMAND AND MESSAGING REQUIREMENTS
5.1	CCSDS Command and Data Format	IRD 3.2.5.2.1
5.2	1553B Command Services Supported	IRD 3.2.5.1
5.3	SI Command/Response Data	IRD 3.2.5.2.2
5.3.1	Housekeeping Data from the DAQ	IRD 3.2.5.2.2.1
5.3.2	Time Distribution to DAQ	IRD 3.2.5.2.2
5.3.3	Ancillary Data To DAQ	IRD 3.2.5.2.3
5.3.3.1	Attitude	IRD 3.2.5.2.3.1
5.3.3.2	Orbit Position Vector	IRD 3.2.5.2.3.2
5.3.3.3	Observation ID	IRD 3.2.5.2.3.3
5.3.4	Ancillary Data Downlink	IRD 3.2.5.2.3
5.4	Observatory Pointing Commands	IRD 3.2.5.2.5, IRD 3.2.5.2.6
5.4.1	Transient Event Control	IRD 3.2.5.2.5.3
5.5	Transient Alert Message	IRD 3.2.5.2.6
5.5.1	Transient Message Type
5.5.2	Transient Message Coordinates	IRD 3.2.5.2.6
5.5.3	Transient Message Timestamp
5.5.4	Transient Message Quality Factor
5.5.5	Transient Message Sequence Number
5.5.6	Transient Message Revision Number
5.5.7	Transient Message Variable Text
5.5.8	Transient Message Latency
5.6	Hardware Commands
5.6.1	ACD Hardware Commands
5.6.2	CAL Hardware Commands
5.6.3	TKR Hardware Commands
5.6.4	DAQ Hardware Commands
5.7	DAQ Software Loads Command
5.8	DAQ Memory Dump Command
5.9	Command Verification
5.10	Configuration State Commands
5.10.1	Configuration State Table
5.10.2	Configuration State Table Updates
5.10.3	Configuration State Initialization
5.10.4	Command Configuration Verification
5.11	Command Acknowledgement
5.11.1	Command Counter
5.11.1.1	Receive Command Counter
5.11.1.2	Execute Command Counter
5.11.1.3	Reject Command Counter
5.11.2	Command Copy
5.11.3	Command Timestamp
5.11.4	Command Verification
5.11.5	Command Acknowledgement Packet (CAP)
5.11.5.1	CAP Command Counter
5.11.5.2	CAP Timestamp
5.11.5.3	CAP Command Echo
5.11.5.4	CAP Command Verification
5.11.5.5	CAP Checksum
5.11.6	CAP Transmission
5.12	Operating Modes
5.12.1	Initialization Mode
5.12.2	Checkout Mode
5.12.3	Calibration Mode
5.12.4	Test Mode
5.12.5	Pointed Mode
5.12.6	Level 1 Trigger Modes
5.12.7	Level 2 and Level 3 Trigger Modes
5.12.8	Power Constrained Mode
5.12.9	Time Dependent Event Mode
5.12.9.1	Gamma-Ray Bursts (GRB)
5.12.9.1.1	Peak GRB trigger rate
5.12.9.1.2	GRB detection
5.12.9.1.3	GRB alert message
5.12.9.1.4	GRB Dead Time
5.12.9.2	Active Galactic Nuclei
5.12.9.3	Solar flares
5.12.10	South Atlantic Anomaly Environment
5.12.10.1	SAA Detection
5.12.10.2	SAA Calculation
5.12.10.3	SAA Mode
6	INSTRUMENT HEALTH HOUSEKEEPING REQUIREMENTS
6.1	Temperature monitors
6.1.1	ACD Temperature Monitors
6.1.2	CAL Temperature Monitors
6.1.3	TKR Temperature Monitors
6.1.4	DAQ Temperature Monitors
6.1.4.1	Power Supply Temperature Monitors
6.1.4.2	Electronics Board Temperature Monitors
6.1.4.3	Grid Temperature Monitors
6.2	Input Voltage Monitors
6.3	Output Voltage Monitors
6.4	Input Current Monitor
6.5	Power Supply Current Monitors
6.6	Strain gauges

Appendix B: Requirements Justification Matrix

DAQRD Section	DAQRD Requirement	Justification
3	EVENT DATA FLOW REQUIREMENTS
3.1	Event Flow Rate
3.2	DAQ Contribution to Dead Time
3.3	Anti-Coincidence Detector (ACD) Event Data
3.3.1	ACD Veto Word Readout
3.3.2	ACD CNO Word Readout
3.3.3	ACD PHA Readout
3.3.4	ACD Readout Modes
3.3.4.1	ACD Zero Suppressed Mode
3.3.4.2	ACD Calibration Modes
3.3.4.2.1	ACD Sampled, Calibration Mode
3.3.4.2.2	ACD Continuous, Calibration Mode
3.3.4.3	ACD Nominal Mode
3.3.5	ACD Average Event Size
3.3.6	ACD Zero Suppressed Word Size
3.4	Calorimeter (CAL) Event Data
3.4.1	Multiple Word Formats
3.4.1.1	Zero Suppressed Word Format
3.4.1.1.1	Zero Suppressed Format Word Size
3.4.1.1.2	Zero Suppressed Format Number of Words
3.4.1.2	Extended Word Format
3.4.1.2.1	Extended Word Format Size
3.4.1.2.2	Extended Word Format Number of Words
3.4.2	CAL Single and 4 Gain Readout
3.4.2.1	Single Gain Readout
3.4.2.1.1	Fixed Gain, Single Gain Readout
3.4.2.1.2	Autorange, Single Gain Readout
3.4.2.2	Four Gain Readout
3.4.3	CAL Readout Modes
3.4.3.1	Nominal Mode Readout
3.4.3.1.1	Nominal Mode, Single Gain Readout
3.4.3.1.2	Nominal Mode, 4 Gain Readout
3.4.3.2	Calibration Mode Readout
3.4.3.2.1	Calibration Mode Autorange Readout
3.4.3.2.2	Calibration Mode 4 Gain Readout
3.4.3.2.3	Calibration Mode 4 Gain, Zero Suppressed Readout
3.4.4	CAL Zero Suppressed Average Event Size
3.4.5	CAL Zero Suppressed Worst Case Event Size
3.5	Tracker (TKR) Event Data
3.5.1	TKR Dual Readout
3.5.2	TKR Single Cable Readout
3.5.3	TKR Front End Buffering
3.5.4	TKR Word Formats
3.5.4.1	TKR Header Word
3.5.4.2	TKR Time Over Threshold Word
3.5.4.3	TKR Hit Address Word
3.5.4.4	TKR CRC Word
3.5.5	TKR Readout Formats
3.5.5.1	Nominal Readout Mode
3.5.5.2	CRC Readout Mode
3.5.6	TKR Average Event Size
3.6	Trigger (L1T) Event Data
3.7	Event Data Bit Rates
3.7.1	ACD Maximum Discriminator Data Rate Output
3.7.2	ACD Average PHA Data Rate Output
3.7.3	ACD Maximum PHA Data Rate Output
3.7.4	CAL Average Data Rate Output
3.7.5	CAL Maximum Data Rate Output
3.7.6	TKR Average Data Rate Output
3.7.7	TKR Maximum Data Rate Output
3.7.8	L1T Data Rate Output
4	SCIENCE HOUSEKEEPING REQUIREMENTS
4.1	ACD Rate Counters
4.1.1	ACD Rate Counter Word	A wide range of readout rates is needed for testing and operations. In order to accommodate the wide range of counts expected, a logarithmic type readout permits both rapid ground testing and low rate on orbit operations to minimize bit rates while satisfying the diagnostic monitoring of the ACD.
4.1.2	ACD Discriminator Rate Counters
4.1.3	ACD Supertile Rate Counters
4.1.4	ACD Zone Rate Counters	The zone rate counters must be capable of very fast sample rates in order to support the GRB monitor function in which bursts may last for only 10 milliseconds or less with potentially thousands of photons.
4.2	CAL Rate Counters
4.2.1	CAL Rate Counter Word
4.2.2	CAL Discriminator Rate Counters	These rate counters are for diagnostic purposes only.
4.3	TKR Rate Counters
4.4	Science Housekeeping Readout Rate	The readout sample rate must be programmable to accommodate ground testing and on orbit operations.
4.5	Science Housekeeping Sample Rate Range	The high speed samples will be used with the science counters to support GRB modes and special diagnostics. The slower sample rates will be used on orbit to reduce the average bit rates while providing the assurance of proper operation.
4.6	Rate Counter Readout Synchronization	The primary requirement in synchronization is for time epoch knowledge. It is acceptable to have skew between counters.
4.7	Science Housekeeping Bit Rate
4.7.1	ACD Rate Counter Maximum Bit Rate
4.7.2	ACD Rate Counter Average Bit Rate
4.7.3	ACD Zone Counter Maximum Bit Rate
4.7.4	CAL Rate Counter Maximum Bit Rate
4.7.5	CAL Rate Counter Average Bit Rate
4.7.6	TKR Rate Counter Maximum Bit Rate
4.7.7	TKR Rate Counter Average Bit Rate
5	COMMAND AND MESSAGING REQUIREMENTS
5.1	CCSDS Command and Data Format
5.2	1553B Command Services Supported
5.3	SI Command/Response Data
5.3.1	Housekeeping Data from the DAQ
5.3.2	Time Distribution to DAQ
5.3.3	Ancillary Data To DAQ
5.3.3.1	Attitude
5.3.3.2	Orbit Position Vector
5.3.3.3	Observation ID
5.3.4	Ancillary Data Downlink
5.4	Observatory Pointing Commands
5.4.1	Transient Event Control
5.5	Transient Alert Message
5.5.1	Transient Message Type
5.5.2	Transient Message Coordinates
5.5.3	Transient Message Timestamp
5.5.4	Transient Message Quality Factor
5.5.5	Transient Message Sequence Number
5.5.6	Transient Message Revision Number
5.5.7	Transient Message Variable Text
5.5.8	Transient Message Latency	Coordination with ground based and other spacecraft must be performed in a timely manner because of the time frame that transient phenomena such as GRBs last (a few seconds to minutes.) The propagation delays and response time for instruments is in the range of seconds, so rapid response within a few seconds or less is desirable.
5.6	Hardware Commands
5.6.1	ACD Hardware Commands
5.6.2	CAL Hardware Commands
5.6.3	TKR Hardware Commands
5.6.4	DAQ Hardware Commands
5.7	DAQ Software Loads Command
5.8	DAQ Memory Dump Command
5.9	Command Verification
5.10	Configuration State Commands
5.10.1	Configuration State Table	Multiple CSTs provide a means of rapidly and repeatably configuring the instrument in different modes to support test, checkout, and operating modes.
5.10.2	Configuration State Table Updates	This table provides a means of tracking the current configuration as well as reinitializing the instrument.
5.10.3	Configuration State Initialization
5.10.4	Command Configuration Verification
5.11	Command Acknowledgement
5.11.1	Command Counter
5.11.1.1	Receive Command Counter
5.11.1.2	Execute Command Counter
5.11.1.3	Reject Command Counter
5.11.2	Command Copy
5.11.3	Command Timestamp
5.11.4	Command Verification
5.11.5	Command Acknowledgement Packet (CAP)
5.11.5.1	CAP Command Counter
5.11.5.2	CAP Timestamp
5.11.5.3	CAP Command Echo
5.11.5.4	CAP Command Verification
5.11.5.5	CAP Checksum
5.11.6	CAP Transmission
5.12	Operating Modes
5.12.1	Initialization Mode
5.12.2	Checkout Mode
5.12.3	Calibration Mode
5.12.4	Test Mode
5.12.5	Pointed Mode
5.12.6	Level 1 Trigger Modes
5.12.7	Level 2 and Level 3 Trigger Modes
5.12.8	Power Constrained Mode
5.12.9	Time Dependent Event Mode
5.12.9.1	Gamma-Ray Bursts (GRB)
5.12.9.1.1	Peak GRB trigger rate
5.12.9.1.2	GRB detection
5.12.9.1.3	GRB alert message
5.12.9.1.4	GRB Dead Time
5.12.9.2	Active Galactic Nuclei
5.12.9.3	Solar flares
5.12.10	South Atlantic Anomaly Environment
5.12.10.1	SAA Detection
5.12.10.2	SAA Calculation
5.12.10.3	SAA Mode
6	INSTRUMENT HEALTH HOUSEKEEPING REQUIREMENTS
6.1	Temperature monitors
6.1.1	ACD Temperature Monitors
6.1.2	CAL Temperature Monitors
6.1.3	TKR Temperature Monitors
6.1.4	DAQ Temperature Monitors
6.1.4.1	Power Supply Temperature Monitors
6.1.4.2	Electronics Board Temperature Monitors
6.1.4.3	Grid Temperature Monitors
6.2	Input Voltage Monitors
6.3	Output Voltage Monitors
6.4	Input Current Monitor
6.5	Power Supply Current Monitors
6.6	Strain gauges

Appendix C: Requirements Verification Matrix

The verification of items will be established in a separate document.

Appendix D: Nomenclature and Abbreviations

ACD	Anti-Coincidence Detector including detector electronics
ACD CNO	The signal developed within the ACD from the high level discriminator
ACD Veto	The signal developed within the ACD from the low level discriminator.
CAL	CsI Calorimeter detector including detector electronics
CAL HI TREQ	The signal developed within the CAL detector module from a high level discriminator which indicates a high level of energy deposition within the CAL.
CAL LO TREQ	The signal developed within the CAL detector module from a low level discriminator which detects the start of an event.
DAQ	Data Acquisition System
GRB	Gamma-Ray Burst
GRBM	Gamma-Ray Burst Monitor: the secondary instrument on the GLAST mission
GTFE	Glast Tracker Front End: ASIC interface to the SSD
GTRC	Glast Tracker Readout Controller: ASIC interface chip between the GTFE and the TEM Tracker Readout Interface
Instrument	The complete Large Area Telescope instrument including 16 TKR modules, 16 CAL modules, and redundant ACD and SIU modules together with the grid and all portions of the observatory other than the SC and the GRBM.
L1T	The global signal which causes the entire instrument to latch and begin readout of an event
L1TQ	The signals from each tower which are logically combined to form the L1T signal
LAT	Large Area Telescope
Module	One of 16 CAL or 16 TKR modules, 2 ACD modules, or 2 SIU modules.
SAA	South Atlantic Anomaly: A region of high flux of energetic protons and electrons in the range of a few tens of MeV.
SC	Spacecraft
SIU	Spacecraft Interface Unit: Interface between the LAT and the Spacecraft
SSD	Silicon Strip Detector
TACK	The signal delivered back to the detector modules as a result of an L1T
TEM	Tower Electronics Module: unit which houses the DAQ in each tower
TKR	Tracker
TKR Trigger Requests (TKR TREQ)	Signals developed within the TKR detector modules from discriminators which detect the start of an event. Also called Fast-OR.
Tower	One TKR, one CAL, and one TEM constitute each tower. There are 16 towers in the LAT.
Tracker	Silicon Strip Detector tracker including GTFE, hybrid, and GTRC

E 1