Attachment_3_WS-32820A_GCS-Velocimeter_IDS.pdf

DAHLGREN DIVISION

NAVAL SURFACE WARFARE CENTER

DAHLGREN, VIRGINIA 22448-5100

WS-32820A

INTERFACE DESIGN SPECIFICATION

FOR THE

VELOCIMETER MK 5 MOD 0

AND THE GUN COMPUTER SYSTEM

MK 160 MODS 4 AND FOLLOW

REVISION A

6 JANUARY 2003

Prepared By:

Naval Fires Systems Branch (Code T25) Naval Surface Warfare Center, Dahlgren Division 17320 Dahlgren Road, Dahlgren, Virginia 22448-5100 and

ACS/Synetics 16539 Commerce Drive, Suite 10 King George, Virginia 22485-5806

DISTRIBUTION STATEMENT D: Distribution authorized to DoD and DoD contractors only; operational use;

6 January 2003. Other requests for this document shall be referred to the Naval Surface Warfare Center, Dahlgren Division, Code T25, Dahlgren, VA 22448-5100.

DESTRUCTION NOTICE - For unclassified, limited distribution documents; destroy by any method that will prevent disclosure of contents or reconstruction of the document.

WS-32820A

A

LIST OF EFFECTIVE PAGES

The total number of pages in Revision A of this document is 74, consisting of the following:

Page Number Change Number

Title Page and A 0 i through iv (blank) 0

1-1 through 1-4 (blank) 0 2-1 and 2-2 (blank) 0 3-1 and 3-2 (blank) 0

4-1 and 4-2 0 5-1 and 5-2 0

6-1 through 6-6 0 7-1 and 7-2 (blank) 0 8-1 through 8-34 0

9-1 and 9-2 0 A-1 and A-2 0

B-1 through B-4 0 C-1 through C-4 0

D-1 and D-2 (blank) 0 E-1 and E-2 (blank) 0

* A zero in the change column indicates an original page.

INTERFACE DESIGN SPECIFICATION

FOR THE VELOCIMETER MK 5 MOD 0

AND THE GUN COMPUTER SYSTEM

MK 160 MODS 4 AND FOLLOW

6 JANUARY 2003

Signature Date

Raymond A. Ripollone Mk 34 GWS Project Manager

NSWCDD T206

Date

Henry T. Rowland III Mk 34 GWS System Engineer

NSWCDD T25

E. W. Culler GWS Division

NSWC PHD-LD 4K12

Prepared by:

Naval Fires Systems Branch (Code T25) Naval Surface Warfare Center, Dahlgren Division

17320 Dahlgren Road, Dahlgren, Virginia 22448-5100 and

ACS/Synetics 16539 Commerce Drive, Suite 10

King George, Virginia 22485-5806

CHANGE RECORD

Change Number Date of Change Reason For Change

A

21 November 2002

6 January 2003

Original issue

Updated to incorporate GCS Mods 8, 9, and 10

6 January 2003 i IDS for Velocimeter Mk 5 Mod 0 GCS Mk 160 Mods 4 and Follow

CONTENTS

Section Page

1 INTRODUCTION ........................................................................................................... 1-1

1.1 PURPOSE ........................................................................................................................ 1-1

1.2 RESPONSIBILITY.......................................................................................................... 1-1

1.3 SCOPE ............................................................................................................................. 1-1

1.4 GMP FUNCTIONAL SUMMARY ................................................................................. 1-1

1.5 VELOCIMETER FUNCTIONAL SUMMARY ............................................................. 1-2

1.6 CONTENT DESCRIPTION ............................................................................................ 1-2

2 APPLICABLE DOCUMENTS ....................................................................................... 2-1

3 INTERFACE SIGNAL SUMMARY CROSS-REFERENCE ........................................ 3-1

4 INTERFACE SIGNAL DEFINITION LIST ................................................................... 4-1

5 NARRATIVE SIGNAL FLOW TABLE......................................................................... 5-1

5.1 GENERAL ....................................................................................................................... 5-1

5.2 INITIALIZATION ........................................................................................................... 5-1

5.3 NORMAL OPERATION................................................................................................. 5-1

6 INTERDIGITAL PROCESSOR COMMUNICATIONS................................................ 6-1

6.1 GENERAL ....................................................................................................................... 6-1

6.2 COMMUNICATIONS CONTROL (GCS MODS 4, 6 AND 8) ..................................... 6-1

6.2.1 INTERFACE HARDWARE CHARACTERISTICS ...................................................... 6-1

6.2.2 DEFINITION OF TERMS .............................................................................................. 6-2

6.2.3 INTERFACE ENABLE/DISABLE PROCEDURES ...................................................... 6-3

6.2.4 GMP/VELOCIMETER I/O PROCESSING REQUIREMENTS .................................... 6-4

6.3 COMMUNICATIONS CONTROL (GCS MODS 9 AND 10) ....................................... 6-5

6.3.1 INTERFACE HARDWARE CHARACTERISTICS ...................................................... 6-5

6.3.2 DEFINITION OF TERMS .............................................................................................. 6-6

6.3.3 INTERFACE ENABLE SEQUENCE ............................................................................. 6-6

6.3.4 INTERFACE DISABLE SEQUENCE ............................................................................ 6-6

6.4 COMMUNICATIONS CONVENTIONS ....................................................................... 6-6

7 DATA UNIT DESCRIPTIONS ....................................................................................... 7-1

8 MESSAGE DESCRIPTIONS .......................................................................................... 8-1

8.1 GENERAL ....................................................................................................................... 8-1

8.2 GMP TO VELOCIMETER MESSAGE DESCRIPTION ............................................... 8-2

8.2.1 GMP REQUEST MEASUREMENT UNIT MESSAGE (MT001) ................................ 8-2

8.2.2 GMP CHANGE MEASUREMENT UNIT MESSAGE (MT002) .................................. 8-2

8.2.3 GMP REQUEST TRIGGER METHOD MESSAGE (MT003) ...................................... 8-2

CONTENTS (Continued)

IDS for Velocimeter Mk 5 Mod 0 ii 6 January 2003

8.2.4 GMP CHANGE TRIGGER METHOD MESSAGE (MT004) ....................................... 8-3

8.2.5 GMP REQUEST ANTENNA OFFSET MESSAGE (MT005) ....................................... 8-3

8.2.6 GMP CHANGE ANTENNA OFFSET MESSAGE (MT006) ........................................ 8-3

8.2.7 GMP REQUEST ANTENNA BACKSET MESSAGE (MT007) ................................... 8-3

8.2.8 GMP CHANGE ANTENNA BACKSET MESSAGE (MT008) .................................... 8-4

8.2.9 GMP REQUEST FIRING RATE MESSAGE (MT009) ................................................. 8-4

8.2.10 GMP CHANGE FIRING RATE MESSAGE (MT010) .................................................. 8-4

8.2.11 GMP REQUEST DECELERATION MESSAGE (MT011) ........................................... 8-4

8.2.12 GMP CHANGE DECELERATION MESSAGE (MT012) ............................................ 8-5

8.2.13 GMP REQUEST REARM DELAY MESSAGE (MT013) ............................................. 8-5

8.2.14 GMP CHANGE REARM DELAY MESSAGE (MT014) .............................................. 8-5

8.2.15 GMP REQUEST TRIGGER LEVEL MESSAGE (MT015) ........................................... 8-5

8.2.16 GMP CHANGE TRIGGER LEVEL MESSAGE (MT016) ............................................ 8-5

8.2.17 GMP REQUEST MINIMUM ENERGY MESSAGE (MT017) ..................................... 8-6

8.2.18 GMP CHANGE MINIMUM ENERGY MESSAGE (MT018)....................................... 8-6

8.2.19 GMP REQUEST TRIGGER BIAS MESSAGE (MT019) .............................................. 8-6

8.2.20 GMP CHANGE TRIGGER BIAS MESSAGE (MT020) ............................................... 8-7

8.2.21 GMP REQUEST INITIAL DELAY MESSAGE (MT021) ............................................ 8-7

8.2.22 GMP CHANGE INITIAL DELAY MESSAGE (MT022) .............................................. 8-7

8.2.23 GMP REQUEST BRACKETING OPTION MESSAGE (MT023) ................................ 8-7

8.2.24 GMP CHANGE BRACKETING OPTION MESSAGE (MT024) ................................. 8-8

8.2.25 GMP REQUEST SOFTWARE VERSION MESSAGE (MT025) .................................. 8-8

8.2.26 GMP REQUEST FREQUENCY MESSAGE (MT026) .................................................. 8-8

8.2.27 GMP CHANGE FREQUENCY MESSAGE (MT027) ................................................... 8-9

8.2.28 GMP CHANGE VELOCITY RANGE MESSAGE (MT028) ........................................ 8-9

8.2.29 GMP REQUEST SELF-TEST MESSAGE (MT029) ................................................... 8-10

8.2.30 GMP REQUEST DIAGNOSTIC TEST MESSAGE (MT030) .................................... 8-10

8.2.31 GMP REQUEST POINT SPACING MESSAGE (MT031) .......................................... 8-10

8.2.32 GMP CHANGE POINT SPACING MESSAGE (MT032) ........................................... 8-11

8.3 VELOCIMETER TO GMP MESSAGE DESCRIPTION ............................................. 8-12

8.3.1 VEL RETURN MEASUREMENT UNIT MESSAGE (MT101) ................................. 8-13

8.3.2 VEL CHANGED MEASUREMENT UNIT MESSAGE (MT102) ...............................8.13

8.3.3 VEL RETURN TRIGGER METHOD MESSAGE (MT103) ....................................... 8-14

8.3.4 VEL CHANGED TRIGGER METHOD MESSAGE (MT104) ................................... 8-14

8.3.5 VEL RETURN ANTENNA OFFSET MESSAGE (MT105) ........................................ 8-15

8.3.6 VEL CHANGED ANTENNA OFFSET MESSAGE (MT106) .................................... 8-15

8.3.7 VEL RETURN ANTENNA BRACKET MESSAGE (MT107) ................................... 8-16

8.3.8 VEL CHANGED ANTENNA BRACKET MESSAGE (MT108) ................................ 8-16

8.3.9 VEL RETURN FIRING RATE MESSAGE (MT109) .................................................. 8-17 8.3-10 VEL CHANGED FIRING RATE MESSAGE (MT110) .............................................. 8-17

8.3.11 VEL RETURN DECELERATION MESSAGE (MT111) ............................................ 8-18

8.3.12 VEL CHANGED DECELERATION MESSAGE (MT112) ........................................ 8-18

8.3.13 VEL RETURN REARM DELAY MESSAGE (MT113) .............................................. 8-19

CONTENTS (Continued)

6 January 2003 iii IDS for Velocimeter Mk 5 Mod 0

8.3.14 VEL CHANGED REARM DELAY MESSAGE (MT114) .......................................... 8-19

8.3.15 VEL RETURN TRIGGER LEVEL MESSAGE (MT115) ........................................... 8-20

8.3.16 VEL CHANGED TRIGGER LEVEL MESSAGE (MT116) ........................................ 8-20

8.3.17 VEL RETURN MINIMUM ENERGY MESSAGE (MT117) ...................................... 8-21

8.3.18 VEL CHANGED MINIMUM ENERGY MESSAGE (MT1180 .................................. 8-21

8.3.19 VEL RETURN TRIGGER BIAS MESSAGE (MT119) ............................................... 8-22

8.3.20 VEL CHANGED TRIGGER BIAS MESSAGE (MT120) ........................................... 8-22

8.3.21 VEL RETURN INITIAL DELAY MESSAGE (MT121) ............................................. 8-23

8.3.22 VEL CHANGED INITIAL DELAY MESSAGE (MT122) .......................................... 8-23

8.3.23 VEL RETURN BRACKETING OPTION MESSAGE (MT123) ................................. 8-24

8.3.24 VEL CHANGED BRACKETING OPTION MESSAGE (MT124) ............................. 8-24

8.3.25 VEL RETURN SOFTWARE VERSION MESSAGE (MT125)................................... 8-25

8.3.26 VEL RETURN FREQUENCY MESSAGE (MT126) .................................................. 8-25

8.3.27 VEL CHANGED FREQUENCY MESSAGE (MT127) ............................................... 8-26

8.3.28 VEL CHANGED VELOCITY RANGE MESSAGE (MT128) .................................... 8-27

8.3.29 VEL RETURN SELF-TEST MESSAGE (MT129) ...................................................... 8-28

8.3.30 VEL RETURN DIAGNOSTIC TEST MESSAGE (MT130) ....................................... 8-31

8.3.31 VEL RETURN POINT SPACING MESSAGE (MT131)............................................. 8-31

8.3.32 VEL CHANGED POINT SPACING MESSAGE (MT132) ......................................... 8-32

8.3.33 VEL INITIAL VELOCITY MESSAGE (MT133) ........................................................ 8-33

8.3.34 VEL POWER LOW FAULT MESSAGE (MT134) ..................................................... 8-33

8.3.35 VEL POWER OK FAULT MESSAGE (MT135) ......................................................... 8-34

8.3.36 VEL ENTRY ERROR MESSAGE (MT136) ................................................................ 8-34 9 ACRONYMS ................................................................................................................... 9-1

APPENDIXES

Appendix Page

A VELOCIMETER PARAMETER DESCRIPTIONS ...................................................... A-1 B INITIALIZATION AND VELOCITY RANGE SETTINGS ........................................ B-1 C VELOCIMETER ENABLING DIAGRAMS................................................................. C-1 D GMCP CONFIGURATION ........................................................................................... D-1 E ASCII CHARACTER MAPS .......................................................................................... E-1

IDS for Velocimeter Mk 5 Mod 0 iv 6 January 2003

ILLUSTRATIONS

Figure Page

6-1 GMP TO VELOCIMETER INTERFACE (GCS MK 160 MODS 4, 6 AND 8) ................ 6-2 6-2 RS-232 SIGNAL FORMAT ................................................................................................ 6-5 6-3 GCSC TO VELOCIMETER INTERFACE (GCS MK 160 MODS 9 & 10) ...................... 6-6 C-1 GWS MK 34 MOD 0 (GCS MK 160 MODS 4 AND 6) .................................................... C-1 C-2 GWS MK 34 MOD 1 (GCS MK 160 MOD 8) ................................................................... C-2 C-3 GWS MK 34 MOD 1 (GCS MK 160 MODS 9 AND 10) .................................................. C-3

TABLES

Table Page

4-1 SIGNAL DEFINITION LIST FOR GMP TO VELOCIMETER ........................................ 4-1 4-2 SIGNAL DEFINITION LIST FOR VELOCIMETER TO GMP ........................................ 4-2 5-1 INITIALIZATION SIGNAL FLOW ................................................................................... 5-1 5-2 NORMAL OPERATION EVENTS .................................................................................... 5-2

B-1 MK 45 MOD 2 GUN MOUNT - VELOCIMETER INITIALIZATION (GMP

MESSAGES) ...................................................................................................................... B-1

B-2 MK 45 MOD 2 GUN MOUNT - VELOCIMETER INITIALIZATION (VEL

MESSAGES) ................................................................................................... B-2

B-3 MK 45 MOD 2 GUN MOUNT - VELOCITY RANGE SETTINGS (GMP MESSAGES)

.......................................................................................................................... B-3

B-4 MK 45 MOD 2 GUN MOUNT - VELOCITY RANGE SETTINGS (VEL MESSAGES)

.......................................................................................................................... B-3

B-5 MK 45 MOD 4 GUN MOUNT - VELOCIMETER INITIALIZATION (GMP

MESSAGES) ................................................................................................... B-4

B-6 MK 45 MOD 4 GUN MOUNT - VELOCIMETER INITIALIZATION (GMP

MESSAGES) ...................................................................................................................... B-5 D-1 GMCP PERIPHERAL PORTS CONFIGURATION MENU ........................................ D-1 E-1 ASCII CHARACTER MAP ............................................................................................ E-1

6 January 2003 1-1 IDS for Velocimeter Mk 5 Mod 0

1 INTRODUCTION

1.1 PURPOSE

This Interface Design Specification (IDS) describes and provides configuration control for the interface between the Gun Mount Processor (GMP) and the Mk 5 Mod 0 Velocimeter (VEL), which are subsystems of the DDG 51 Gun Computer System (GCS). This IDS provides a description of initiation and transfer of control signals, interface status messages, and projectile initial velocity (IV) data between the GMP and the VEL.

1.2 RESPONSIBILITY

The technical content of this specification is the responsibility of the Gun Weapon System (GWS) Design Agent, NSWC Dahlgren Division (NSWCDD), Code T25, Dahlgren, Virginia.

1.3 SCOPE

This IDS contains the detailed information required for design and control of the GMP/VEL interface of the GCS Mk 160 Mods 4, 6, 8, 9, and 10. It specifies interface requirements for communications protocol, data message formats, timing, interface testing, and disposition of IV data transferred across the GMP/VEL interface.

1.4 GMP FUNCTIONAL SUMMARY

The GMP operational program (OP) performs ballistics computations and generates gun orders for the Gun Mount (GM) Mk 45 Mods 2 and 4 for targets assigned by the Gun Console Computer (GCC). The GMP OP computes ownship and target position data for Naval Gun Fire Support (NGFS) targets assigned by the GCC. It provides the GCC with data necessary to monitor and control gun engagements, and it supports displays and controls at the gun mount to permit casualty mode operation in the event of loss of the GCC. The Mod 2 GM is used with GCS Mods 4, 6, and 10; and the Mod 4 GM is used with GCS Mods 8 and 9. The following functions are performed by the GMP OP in support of the GMP/VEL interface:

a. Check setup parameters and, if necessary, transmit setup commands to the Velocimeter.

b. Transmit Velocity Range change commands to the Velocimeter.

c. Receive IV messages from Velocimeter.

d. Validate received IV messages.

e. Compute and maintain average of received IV messages.

f. Monitor Velocimeter responses for faults, errors, or timeouts.

g. Command Velocimeter self-test or diagnostic test as required by operator.

IDS for Velocimeter Mk 5 Mod 0 1-2 6 January 2003

In the GCS Mod 9 and 10, the GMP and GCC functions are collocated into a single software entity within the Mk 119 Gun Computer System Cabinet (GCSC). In this document, reference to the GMP and/or the GCC for these GCS modifications should be interpreted as the GCSC. The interface between the GCSC and the Velocimeter is in two stages, via the Mk 437 Mod 2 Gun Mount Control Panel (GMCP).

1.5 VELOCIMETER FUNCTIONAL SUMMARY

The Velocimeter is a single-purpose radar that senses the muzzle velocity of a projectile fired from the Mk 45 GM. A description of the Velocimeter parameters is provided in Appendix A.

The Velocimeter operates under the control of the GMP OP. Once initialized by GMP OP commands, the Velocimeter will automatically turn on radio frequency (RF) power when the gun is fired, sense the IV of the projectile fired, and transmit that velocity to the GMP OP via the interface. The following specific functions are performed by the Velocimeter in support of the GMP/VEL interface:

a. Accept commands from GMP.

b. Return command response messages to GMP.

c. Set bandpass in response to Velocity Range commands from GMP.

d. Sense projectile IV when gun is fired.

e. Transmit IV message to GMP.

f. Execute self-test or diagnostic test when ordered by GMP.

g. Transmit test results to GMP.

h. Transmit power fault messages.

1.6 CONTENT DESCRIPTION

The remainder of this document specifies the interface design requirements to implement the GMP/VEL interface, organized as follows:

Section 2, Applicable Documents, lists the documents used as references in the development of this specification.

Section 3, Interface Signal Summary Cross-Reference, is no longer required and has been deleted in Revision A of this document.

Section 4, Interface Signal Definition List, lists each signal with its message number and purpose. There is a signal definition list for GMP-to-VEL signals and another for VEL-to-GMP signals.

Section 5, Narrative Signal Flow Table, provides logical tabulated groupings of the GMP/VEL interface signals, arranged and numbered in the sequence of normally expected occurrence of events. The groups are named by the function or operation with which they are associated. This table includes signal number and name, origin and destination, conditions for signal initiation, control and display requirements, and amplifying remarks.

6 January 2003 1-3 IDS for Velocimeter Mk 5 Mod 0

Section 6, Interdigital Processor Communications, describes the communication control and conventions (protocol) used in the GMP/VEL interface.

Section 7, Data Unit Descriptions, is redundant with Section 8 and has been deleted in Revision A of this document.

Section 8, Message Descriptions, provides graphic representations and narrative descriptions of the message formats and contents that are exchanged over the GMP/VEL interface. Paragraph

8.2 contains message formats and descriptions for messages transferred from the GMP to the VEL. Paragraph 8.3 contains the same type of information for messages transferred from the VEL to the GMP.

IDS for Velocimeter Mk 5 Mod 0 1-4 6 January 2003

This page has been left blank intentionally.

6 January 2003 2-1 IDS for Velocimeter Mk 5 Mod 0

2 APPLICABLE DOCUMENTS

The following documents have been used as resource material in the development and preparation of this IDS:

DOD-STD-1679A (Navy) Military Standard Software Development, 22 October 1983

DI-E-2135A Interface Design Specification Data Item Description, 22 October

N/A Mk V Velocimeter (AN/UPQ6) Technical Description and

Operating Instructions, Lear Astronics Corporation, May 1991

RF-WS-33950 System Specification for Aegis Destroyer Mk 160 Mod 9 Gun

Computer System, 1 October 2001

SW224-A4-MMO- Maintenance Manual for Gun Computer System Mk 160 Mod 4, 010/MK 160 Mod 4 15 April 1987

TW221-GB-PSP- Gun Weapon System Gun Mount Processor Mk 20 Mod 0 010/EX-34/0 Operational Program Performance Specification, 31 March 1989

WS-33413 System Specification for Aegis Destroyer Mk 160 Mod 8 Gun

Computer System, 11 March 1998

WS-33724 System Specification for Aegis Destroyer Mk 160 Mod 10 Gun Computer System, 1 October 2002

IDS for Velocimeter Mk 5 Mod 0 2-2 6 January 2003

6 January 2003 3-1 IDS for Velocimeter Mk 5 Mod 0

3 INTERFACE SIGNAL SUMMARY CROSS-REFERENCE

This section has been tailored out.

IDS for Velocimeter Mk 5 Mod 0 3-2 6 January 2003

6 January 2003 4-1 IDS for Velocimeter Mk 5 Mod 0

4 INTERFACE SIGNAL DEFINITION LIST

This section provides a summary of the GMP-to-VEL and VEL-to-GMP messages.

Table 4-1. Signal Definition List for GMP to VEL

Message Number Message Name Command

MT001 GMP Request Measurement Unit UT MT002 GMP Change Measurement Unit UF MT003 GMP Request Trigger Method TM MT004 GMP Change Trigger Method PT MT005 GMP Request Antenna Offset AO MT006 GMP Change Antenna Offset AOXXX MT007 GMP Request Antenna Backset AB MT008 GMP Change Antenna Backset ABXXX MT009 GMP Request Firing Rate FR MT010 GMP Change Firing Rate FRXXXX MT011 GMP Request Deceleration DC MT012 GMP Change Deceleration DCXXXX MT013 GMP Request Rearm Delay RD MT014 GMP Change Rearm Delay RDXXXX MT015 GMP Request Trigger Level TL MT016 GMP Change Trigger Level TLX MT017 GMP Request Minimum Energy EL MT018 GMP Change Minimum Energy ELXXXX MT019 GMP Request Trigger Bias TB MT020 GMP Change Trigger Bias TBXXXX MT021 GMP Request Initial Delay ID MT022 GMP Change Initial Delay IDXXXX MT023 GMP Request Bracketing Option BR MT024 GMP Change Bracketing Option BRO MT025 GMP Request Software Version SI MT026 GMP Request Frequency SF MT027 GMP Change Frequency SFX MT028 GMP Change Velocity Range VRXXXX MT029 GMP Request Self-Test ST MT030 GMP Request Diagnostic Test DT MT031 GMP Request Point Spacing PS MT032 GMP Change Point Spacing PSX

IDS for Velocimeter Mk 5 Mod 0 4-2 6 January 2003

Table 4-2. Signal Definition List for VEL to GMP

Message Number Message Name Response To

MT101 VEL Return Measurement Unit MT001 MT102 VEL Changed Measurement Unit MT002 MT103 VEL Return Trigger Method MT003 MT104 VEL Changed Trigger Method MT004 MT105 VEL Return Antenna Offset MT005 MT106 VEL Changed Antenna Offset MT006 MT107 VEL Return Antenna Backset MT007 MT108 VEL Changed Antenna Backset MT008 MT109 VEL Return Firing Rate MT009 MT110 VEL Changed Firing Rate MT010 MT111 VEL Return Deceleration MT011 MT112 VEL Changed Deceleration MT012 MT113 VEL Return Rearm Delay MT013 MT114 VEL Changed Rearm Delay MT014 MT115 VEL Return Trigger Level MT015 MT116 VEL Changed Trigger Level MT016 MT117 VEL Return Minimum Energy MT017 MT118 VEL Changed Minimum Energy MT018 MT119 VEL Return Trigger Bias MT019 MT120 VEL Changed Trigger Bias MT020 MT121 VEL Return Initial Delay MT021 MT122 VEL Changed Initial Delay MT022 MT123 VEL Return Bracketing Option MT023 MT124 VEL Changed Bracketing Option MT024 MT125 VEL Return Software Version MT025 MT126 VEL Return Frequency MT026 MT127 VEL Changed Frequency MT027 MT128 VEL Changed Velocity Range MT028 MT129 VEL Return Self-Test Power On, MT029 MT130 VEL Return Diagnostic Test MT030 MT131 VEL Return Point Spacing MT031 MT132 VEL Changed Point Spacing MT032 MT133 VEL Initial Velocity IV Measurement MT134 VEL Power Low Fault Low Power MT135 VEL Power OK Fault Power Recovery MT136 VEL Entry Error Various

6 January 2003 5-1 IDS for Velocimeter Mk 5 Mod 0

5 NARRATIVE SIGNAL FLOW TABLE

5.1 GENERAL

This section provides a narrative signal flow table containing GMP and Velocimeter interface signals arranged and numbered in the sequence of normally expected occurrence of events.

5.2 INITIALIZATION

The following table describes the sequence of events that shall occur during initialization. Each step shall consist of a command message transmitted from GMP to VEL and a response message from VEL to GMP. Appendix B provides the initial parameter settings for each gun mount configuration. In GCS Mods 4 and 6, GMP shall check parameter values prior to changing them.

Table 5-1. Initialization Signal Flow

Step Task GMP → VEL VEL → GMP

1 Confirm communications established between GMP and VEL MT025 MT125

2 Change measurement unit MT002 MT102 3 Change trigger method MT004 MT104 4 Change antenna offset MT006 MT106 5 Change antenna backset MT008 MT108 6 Change firing rate MT010 MT110 7 Change deceleration MT012 MT112 8 Change rearm delay MT014 MT114 9 Change trigger level MT016 MT116 10 Change point spacing (if Mk 45

Mod 4 GM) MT032 MT132

11 Change energy level MT018 MT118 12 Change trigger bias MT020 MT120 13 Change initial delay MT022 MT122 14 Change bracketing MT024 MT124 15 Change frequency MT027 MT127 16 Set velocity range to expected IV of the ammunition selected MT028 MT128

5.3 NORMAL OPERATION

The following table, Table 5-2, describes the events (after initialization) that can cause communication between GMP and VEL. Initialization of each message is described in Section 8 of this document.

IDS for Velocimeter Mk 5 Mod 0 5-2 6 January 2003

Table 5-2. Normal Operation Events

Event GMP → VEL VEL → GMP Remarks

Initial Velocity measurement

MT133

Fire Salvo Signal from the GCC operator causes the GMP to open a buffer to collect the IV for each projectile fired.

VEL sends message when gun is fired. Current IV for projectile type is displayed to operator.

Operator selects different ammunition type

MT028

MT032

MT128

MT132

Velocity range updated then Reset point spacing (if Mk 45 Mod 4 GM).

Operator initiates system test from test page

MT029

MT027

MT129

MT127

Test results displayed to operator then Reset frequency setting.

Operator initiates diagnostic test from test page

MT030 MT130 Test results displayed to operator.

Velocimeter link non-active for 10 seconds

MT025

MT125

This checks the GMP/VEL interface.

Disabled when gun is ready to fire.

Velocimeter low power fault condition

MT134

MT135

VEL sends 1st message when low power is detected. Fault status displayed to operator.

GMP waits for normal power to be restored.

VEL sends 2nd message when normal power is restored.

Note: An incorrect response to any of the GMP-issued commands shall cause the GMP to repeat the command a second time. If the second attempt fails, a fault status shall occur and the GMP shall attempt to re-initialize the Velocimeter. The fault status shall be cleared when a correct command response is received from the Velocimeter. Every time the second command response is incorrect, this cycle shall be repeated until a correct command response is received or the channel is disabled.

6 January 2003 6-1 IDS for Velocimeter Mk 5 Mod 0

6 INTERDIGITAL PROCESSOR COMMUNICATIONS

6.1 GENERAL

This section defines the procedures and conventions required to transfer data and exercise control of the interface between the GMP and the Velocimeter within the GCS Mk 160 Mods 4, 6, 8, 9, and 10. Paragraph 6.2 describes the communications control protocol for the GCS Mods 4, 6, and 8 interface and includes procedures for transferring data across the interface.

Paragraph 6.3 describes the differences between the GCS Mods 9 and 10 and the GCS Mods 4, 6, and 8 interfaces. Paragraph 6.4 presents the communications conventions established to facilitate proper data transfer.

6.2 COMMUNICATIONS CONTROL (GCS MODS 4, 6 AND 8)

6.2.1 Interface Hardware Characteristics

The GMP/VEL interface shall be a modified RS-232 serial interface. As implemented for this application, the interface shall operate asynchronously at 9600 baud with eight data bits, one stop bit, and no parity bits comprising each byte transferred. Three signal lines shall be used: (1) Transmitted Data, (2) Received Data, and (3) Signal Ground.

The physical duplex channel shall consist of one cable. The Data Terminal Ready and Data Set Ready lines of the RS-232 channel shall be jumpered at the output of the AN/UYK-44 to satisfy interface signal processing requirements, since the Velocimeter I/O processing does not provide Data Set Ready. Figure 6-1 illustrates the GMP/VEL interface for GCS Mods 4, 6, and 8.

Figure 6-2 illustrates the RS-232 signal format. A cable wire diagram is provided in Appendix C.

Figure 6-1. GMP to Velocimeter Interface (GCS Mods 4, 6, and 8)

GUN MOUNT

PROCESSOR VELOCIMETER

TRANSMITTED DATA

RECEIVED DATA

DATA SET READY (DSR)

DATA TERMINAL READY (DTR)

SIGNAL GROUND

IDS for Velocimeter Mk 5 Mod 0 6-2 6 January 2003

Figure 6-2. RS-232 Signal Format

6.2.2 Definition of Terms for GMP/VEL Interface

The terms defined in this paragraph are presented here to aid in understanding the detailed descriptions of the GMP/VEL interface.

Buffer A buffer is a group of 8-bit bytes sent from the GMP or received from the Velocimeter. The bytes are packed into 16-bit words within an indexed block of GMP memory. The length of the buffer is established by the type of command or data being transferred. Transfers across the interface are made as two 8-bit bytes for each 16-bit word of GMP memory, with each byte transferred serially. Buffer operations for the GMP/VEL interface are controlled entirely by the GMP OP, with the Velocimeter operating as a slave.

Command Velocimeter commands are transmitted by the GMP as two-, three-, or four-word buffers, depending upon the command.

These commands control the operation and modes of the

Command Response

A command response is a message returned to the GMP by the Velocimeter—one for each command received from the GMP. Each command response is packed into a buffer by the GMP OP and checked for the correct response to the command issued.

Message As applied to the GMP/VEL interface, message types are defined as commands, command responses, initial velocity messages, test results, and Velocimeter fault. These message types vary in number of words and are issued from or received into buffers by the GMP. Each buffer contains only one message. The command messages transmitted by the GMP are contained in pre-canned buffers and are accessed through the use of flags and buffer index pointers.

6 January 2003 6-3 IDS for Velocimeter Mk 5 Mod 0

6.2.3 Interface Enable/Disable Procedures

The GMP/VEL interface shall operate under the control of the GMP; and the Velocimeter shall function as a slave to the GMP. Only the GMP shall be able to enable or disable the interface;

when the interface is disabled by the GMP, no data transfers may be initiated on the interface.

The GWS operator controls the state of the interface and may initiate action to enable or disable the interface at any time. When the interface is enabled after having been disabled, the GMP shall clear the channel and reinitialize the Velocimeter’s parameters.

All Velocimeter commands shall be transmitted from the GMP via the transmit data line of the interface, and all command responses and self-test results are transmitted to the GMP via the receive data line of the interface.

6.2.3.1 Interface Enable Sequence

The interface shall be enabled upon system initialization and may subsequently be disabled only through operator action. Once disabled, the interface may be enabled again by operator action.

The command sequence for the enabling process shall be as follows:

a. GMP OP sends a GMP Request Software Version message (MT025) to the

b. GMP OP receives the VEL Return Software Version message (MT125) from the Velocimeter.

c. GMP OP evaluates the response message. If the response is incorrect or if there is no response, the GMP OP sends an error message to the operator and repeats MT025 until a correct response is received or until the operator intervenes to disable the interface.

d. After the interface is enabled, MT025 is sent approximately every 10 seconds except when the gun is in ready-to-fire mode, at which time MT025 is inhibited.

Following this sequence, the interface will be enabled and ready for initialization. Following initialization, the Velocimeter will be ready to passively record the velocity of a projectile when fired.

6.2.3.2 Interface Disable Sequence

The interface shall be disabled only through operator action. When the operator selects to disable the interface, the GMP OP shall set internal flags that disable the interface for processing purposes. In the disabled state, the Velocimeter shall be logically inaccessible to the normal cyclic Velocimeter processing module, and no commands shall be issued by the GMP OP until the operator selects to enable the interface.

6.2.3.3 Interface Initialization Sequence

A sequence of commands shall be sent to the Velocimeter during Velocimeter initialization. A list of these commands and the optimal values are included in Section 5 and Appendix B.

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6.2.4 GMP/Velocimeter I/O Processing Requirements

With two exceptions (MT133 Initial Velocity Message and MT134 Velocimeter Power Low Fault Message), the Velocimeter shall operate passively under the control of the GMP OP.

Paragraph 6.2.4.1 describes command message processing requirements, and Paragraph 6.2.4.2 describes IV message and fault message processing.

6.2.4.1 Command Message Processing

The input/output (I/O) processing performed by the GMP OP to send command messages to the Velocimeter shall be as follows:

a. Check flags for command message to transmit.

b. Open a buffer to receive command response from Velocimeter.

c. Transmit flagged command message buffer to Velocimeter.

d. Receive command message response buffer.

e. Evaluate command message response for error indications.

6.2.4.2 IV and Fault Message Processing

The Velocimeter shall be capable of sending unsolicited messages to the GMP for only two reasons: (1) detected IV when a projectile is fired, and (2) Velocimeter fault should one occur.

6.2.4.2.1 IV Message I/O Processing

When initialized, the Velocimeter shall be placed in the passive trigger mode of operation. The accelerometer shall sense gun motion during firing and shall turn the RF on for 1 second, and then off, automatically. Then, the Velocimeter shall calculate the IV and send the IV message to the GMP. The steps for this process shall be as follows:

a. Fire/Salvo is pressed by the operator.

b. GMP OP opens a buffer to receive the IV message data from the Velocimeter.

c. Projectile is fired.

d. Velocimeter turns on RF and calculates the IV.

e. Velocimeter turns off RF.

f. Velocimeter transmits IV message to the GMP OP.

6.2.4.2.2 Velocimeter Fault Message Processing

During periods of interface inactivity, while the interface is enabled, the GMP OP shall open a fault buffer to detect a Velocimeter low-power condition if one should occur. The Velocimeter shall transmit the VEL Power Low Fault message (MT134) to the GMP upon occurrence. The GMP OP shall wait until the Velocimeter transmits a VEL Power OK Fault message (MT135) before clearing the fault status.

6 January 2003 6-5 IDS for Velocimeter Mk 5 Mod 0

6.3 COMMUNICATIONS CONTROL (GCS MODS 9 AND 10)

This paragraph describes the differences in communication between GCS Mods 9 and 10 and GCS Mods 4, 6, and 8. In the GCS Mods 9 and 10, the GMP and GCC functions are collocated into a single software entity within the Mk 119 GCSC. The Velocimeter is attached to the Mk 45 Gun Mount and interfaces with the GCSC via the Mk 437 Mod 2 GMCP.

6.3.1 Interface Hardware Characteristics

Communication between the GCSC and VEL shall be in two stages via the GMCP. The GCSC/GMCP interface shall be fiber-optic Ethernet (100BaseFx), and the GMCP/VEL interface shall be RS-232 serial.

The GCSC/GMCP interface shall use the Transmission Control Protocol/Internet Protocol (TCP/IP). TCP Port 88 of the GMCP shall be used. Specific IP addresses will be defined during the design stage.

The GMCP/VEL interface shall be an RS-232 serial interface operating asynchronously at 9600 baud with eight data bits, one stop bit, and no parity bits. The interface shall use three signal lines: Transmitted Data, Received Data, and Signal Ground. The remaining signal lines (Data Set Ready, Data Terminal Ready, Data Carrier Detect, Request to Send, and Clear to Send) shall not be used and this shall not require jumpers at the output of the GMCP.

The transfer between TCP/IP and RS-232 protocols shall be performed by the GMCP firmware.

Appendix D provides the GMCP configuration.

Figure 6-3 illustrates the GCSC/VEL interface. A cable wire diagram is provided in Appendix C.

Figure 6-3. GCSC to Velocimeter Interface (GCS Mods 9 and 10)

GUN MOUNT

COMPUTER

PANEL

(GCMP)

VELOCIMETER

TRANSMITTED DATA

RECEIVED DATA

SIGNAL GROUND

GUN CONTROL

SYSTEM

CABINET

(GCSC)

FIBER OPTIC

CABLE

IDS for Velocimeter Mk 5 Mod 0 6-6 6 January 2003

6.3.2 Definition of Terms for GCSC/VEL Interface

The terms defined in this paragraph are presented here to aid in understanding the detailed descriptions of the GCSC/VEL interface.

Buffer Contains computer memory for storage of message information.

Command Commands control the operation and modes of the Velocimeter. They are transmitted from the GCSC to the Velocimeter in two stages:

(1) The GCSC writes the message information (American Standard Code for Information Interchange (ACS)II characters) to the GMCP TCP port.

(2) The GMCP then forwards the data to the Velocimeter across the serial interface.

Command Response

A command response is returned to the GCSC by the Velocimeter for each command received. The GMCP forwards the data received on its serial interface to the GCSC across the TCP port.

Message As applied to the GCSC/VEL interface, message types are defined as commands, command responses, initial velocity messages, test results, and Velocimeter fault.

They consist of a string of 8-bit ASCII characters.

6.3.3 Interface Enable Sequence

The first step in the interface enabling process shall be for GCSC to open the GMCP TCP port.

The remaining steps shall be as described in paragraph 6.2.3.1.

6.3.4 Interface Disable Sequence

The interface shall be disabled only through operator action. When the operator selects to disable the interface, the GCSC shall close the GMCP TCP port. Although no messages can be transmitted between GCSC and VEL, the GMCP/VEL side of the interface shall still be enabled (the break is between the GCSC/GMCP). It should be noted that the Velocimeter shall remain active until powered off at the GMCP isolation panel.

6.4 COMMUNICATION CONVENTIONS

The communications on the GMP/VEL interface shall essentially be forced transfers of signals and data. Any time the GMP OP places a command on the interface, the Velocimeter accepts the command and provides a response. Any time the GMP OP anticipates a response or other data from the Velocimeter, it shall open a buffer, monitor time elapsed, and then evaluate the buffer received. Timing on this interface shall be asynchronous.

6 January 2003 7-1 IDS for Velocimeter Mk 5 Mod 0

7 DATA UNIT DESCRIPTIONS

This section has been tailored out because Data Unit Description tables, normally provided in Section 7, are redundant with the Message Format pages of the individual message format sheets contained in Section 8.

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6 January 2003 8-1 IDS for Velocimeter Mk 5 Mod 0

8 MESSAGE DESCRIPTIONS

8.1 GENERAL

This section of the GMP/VEL IDS provides graphic representations and detailed narrative descriptions of the message formats and message contents that are exchanged over the GMP/VEL interface. Section 8.2 contains messages from the GMP to the Velocimeter, and Section 8.3 contains messages from the Velocimeter to the GMP. The two sets of messages are separated by extra spacing to make it easier to identify and distinguish them. Appendix A has a fuller description of the Velocimeter parameters (highlighted in italics in the message descriptions).

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8.2 GMP TO VELOCIMETER MESSAGE DESCRIPTION

Each GMP to Velocimeter message shall consist of a string of ASCII characters ranging from 3 to 7 characters in length. Each character shall reside in one byte (8-bits) of memory.

Appendix E provides a table representing the ASCII character map.

An example of the message representation is as follows:

Message 1 2 3 4 5 6 A B x1 x2 x3 [CR]

The first two characters shall indicate the message type. The middle characters (if applicable) shall represent a number (integer or decimal). The final character shall be a carriage return (CCR), which shall always be used to denote the end of message.

8.2.1 GMP REQUEST MEASUREMENT UNIT MESSAGE (MT001)

The GMP Request Measurement Unit (UT) message (MT001) shall request the Velocimeter to provide its current measurement unit. The Velocimeter shall reply with the VEL Return Measurement Unit message (MT101).

1 2 3

U T [CR]

8.2.2 GMP CHANGE MEASUREMENT UNIT MESSAGE (MT002)

The GMP Change Measurement Unit (UF) message (MT002) shall request the Velocimeter to change its current measurement unit to feet (ft). The Velocimeter shall acknowledge with the VEL Changed Measurement Unit message (MT102).

U F [CR]

8.2.3 GMP REQUEST TRIGGER METHOD MESSAGE (MT003)

The GMP Request Trigger Method (TM) message (MT003) shall request the Velocimeter to provide its current trigger method. The Velocimeter shall reply with the VEL Return Trigger Method message (MT103).

T M [CR]

6 January 2003 8-3 IDS for Velocimeter Mk 5 Mod 0

8.2.4 GMP CHANGE TRIGGER METHOD MESSAGE (MT004)

The GMP Change Trigger Method (PT) message (MT004) shall request the Velocimeter to change its trigger method to Passive. The Velocimeter shall acknowledge with the VEL Changed Trigger Method message (MT104).

P T [CR]

8.2.5 GMP REQUEST ANTENNA OFFSET MESSAGE (MT005)

The GMP Request Antenna Offset (AO) message (MT005) shall request the Velocimeter to provide its current setting for the antenna offset. The Velocimeter shall reply with the VEL Return Antenna Offset message (MT105).

A O [CR]

8.2.6 GMP CHANGE ANTENNA OFFSET MESSAGE (MT006)

The GMP Change Antenna Offset (AOXXX) message (MT006) shall request the Velocimeter to change its setting for the antenna offset to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Antenna Offset message (MT106).

A O x1 x2 x3 [CR]

In this message, x1x2x3 shall be the ASCII representation for the antenna offset in feet (see Appendix B for correct value). A decimal shall be assumed after x2. For example, x1=1, x2=2, and x3=3 shall mean 12.3 ft.

8.2.7 GMP REQUEST ANTENNA BACKSET MESSAGE (MT007)

The GMP Request Antenna Backset (AB) message (MT007) shall request the Velocimeter to provide its current setting for the antenna backset. The Velocimeter shall reply with the VEL Return Antenna Backset message (MT107).

A B [CR]

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8.2.8 GMP CHANGE ANTENNA BACKSET MESSAGE (MT008)

The GMP Change Antenna Backset (ABXXX) message (MT008) shall request the Velocimeter to change its setting for the antenna backset to the number specified in the message.

The Velocimeter shall acknowledge with the VEL Changed Antenna Backset message

(MT108).

A B x1 x2 x3 [CR]

In this message, x1x2x3 shall be the ASCII representation for the antenna offset in feet (see Appendix B for correct value). A decimal point shall be assumed after x2. For example, x1=1, x2=2, and x3=3 shall mean 12.3 ft.

8.2.9 GMP REQUEST FIRING RATE MESSAGE (MT009)

The GMP Request Firing Rate (FR) message (MT009) shall request the Velocimeter to provide its setting for the firing rate. The Velocimeter shall reply with the VEL Return Firing Rate message (MT109).

Message 1 2 3

F R [CR]

8.2.10 GMP CHANGE FIRING RATE MESSAGE (MT010)

The GMP Change Firing Rate (FRXXXX) message (MT010) shall request the Velocimeter to change its setting for the firing rate to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Firing Rate message (MT110).

1 2 3 4 5 6 7 F R x1 x2 x3 x4 [CR]

In this message, x1x2x3x4, shall be the ASCII representation for the firing rate in rounds per minute (see Appendix B for correct value). An integer shall be assumed. For example, x1=1, x2=2, x3=3, x4=4 shall mean 1,234 rounds per minute.

8.2.11 GMP REQUEST DECELERATION MESSAGE (MT011)

The GMP Request Deceleration (DC) message (MT011) shall request the Velocimeter to provide its setting for expected deceleration. The Velocimeter shall reply with the VEL Return Deceleration message (MT111).

D C [CR]

6 January 2003 8-5 IDS for Velocimeter Mk 5 Mod 0

8.2.12 GMP CHANGE DECELERATION MESSAGE (MT012)

The GMP Change Deceleration (DCXXXX) message (MT012) shall request the Velocimeter to change its setting for expected deceleration to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Deceleration message (MT112).

D C x1 x2 x3 x4 [CR]

In this message, x1x2x3x4 shall be the ASCII representation for the expected deceleration in feet/second/second (second2)(see Appendix B for correct value). An integer shall be assumed.

For example, x1=1, x2=2, x3=3, x4=4 shall mean 1,234 feet/second2.

8.2.13 GMP REQUEST REARM DELAY MESSAGE (MT013)

The GMP Request Rearm Delay (RD) message (MT013) shall request the Velocimeter to provide its setting for the rearm delay. The Velocimeter shall reply with the VEL Return Rearm Delay message (MT113).

R D [CR]

8.2.14 GMP CHANGE REARM DELAY MESSAGE (MT014)

The GMP Change Rearm Delay (RDXXXX) message (MT014) shall request the Velocimeter to change its setting for the rearm delay to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Rearm Delay message (MT114).

R D x1 x2 x3 x4 [CR]

In this message, x1x2x3x4 shall be the ASCII representation for the rearm delay in milliseconds (ms) (see Appendix B for correct value). An integer shall be assumed. For example: x1=1, x2=2, x3=3, x4=4 shall mean 1,234 ms.

8.2.15 GMP REQUEST TRIGGER LEVEL MESSAGE (MT015)

The GMP Request Trigger Level (TL) message (MT015) shall request the Velocimeter to provide its setting for the trigger level. The Velocimeter shall reply with the VEL Return Trigger Level message (MT115).

T L [CR]

8.2.16 GMP CHANGE TRIGGER LEVEL MESSAGE (MT016)

IDS for Velocimeter Mk 5 Mod 0 8-6 6 January 2003

The GMP Change Trigger Level (TLX) message (MT016) shall request the Velocimeter to change its setting for the trigger level to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Trigger Level message (MT116).

1 2 3 4 T L x1 [CR]

In this message, x1x2x3x4 shall be the ASCII representation for the final digit (0. x1) trigger level voltage (see Appendix B for correct value). For example, x1=1, x2=2, x3=3, x4=4 shall mean 0.1 volts (V).

8.2.17 GMP REQUEST MINIMUM ENERGY MESSAGE (MT017)

The GMP Request Minimum Energy (EL) message (MT017) shall request the Velocimeter to provide its setting for the energy level. The Velocimeter shall reply with the VEL Return Minimum Energy message (MT117).

E L [CR]

8.2.18 GMP CHANGE MINIMUM ENERGY MESSAGE (MT018)

The GMP Change Minimum Energy (ELXXXX) message (MT018) shall request the Velocimeter to change its setting for the energy level to the number specified in the message.

The Velocimeter shall acknowledge with the VEL Changed Minimum Energy message

(MT118).

E L x1 x2 x3 x4 [CR]

In this message, x1x2x3x4 shall be the ASCII representation for the energy level in decibels (dB) (see Appendix B for correct value). An integer shall be assumed. For example, x1=1, x2=2, x3=3, x4=4 shall mean 1,234 dB.

8.2.19 GMP REQUEST TRIGGER BIAS MESSAGE (MT019)

The GMP Request Trigger Bias (TB) message (MT019) shall request the Velocimeter to provide its setting for the trigger bias. The Velocimeter shall reply with the VEL Return Trigger Bias message (MT119).

T B [CR]

6 January 2003 8-7 IDS for Velocimeter Mk 5 Mod 0

8.2.20 GMP CHANGE TRIGGER BIAS MESSAGE (MT020)

The GMP Change Trigger Bias (TBXXXX) message (MT020) shall request the Velocimeter to change its setting for the trigger bias to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Trigger Bias message (MT120).

T B x1 x2 x3 x4 [CR]

In this message, x1x2x3x4 shall be the ASCII representation for the trigger bias in milliseconds x3=3, x4=4 shall mean 1,234 ms.

8.2.21 GMP REQUEST INITIAL DELAY MESSAGE (MT021)

The GMP Request Initial Delay (ID) message (MT021) shall request the Velocimeter to provide its setting for the initial delay. The Velocimeter shall reply with the VEL Return Initial Delay message (MT121).

I D [CR]

8.2.22 GMP CHANGE INITIAL DELAY) MESSAGE (MT022)

The GMP Change Initial Delay (IDXXXX) message (MT022) shall request the Velocimeter to change its setting for the initial delay to the number specified in the message. The Velocimeter shall acknowledge with the VEL Changed Initial Delay message (MT122).

I D x1 x2 x3 x4 [CR]

In this message, x1x2x3x4 shall be the ASCII representation for the initial…