DEFSTAN 00-19/2(1987) : 1987

CLAUSE
INTRODUCTION
SECTION A: THE DESIGN OBJECTIVES
1 The Naval Environment
2 General Design Principles
3 Basic Parameters
4 Definition of Terms
Figure 1.1 Physical Configuration of the Highway
Figure 1.2 Provision of Redundancy for the Highway
SECTION B: THE TERMINAL UNIT INTERCONNECTION SPECIFICATION
1 Highway Configuration and Physical Construction
  1.1 Configuration
  1.2 Cables and Connectors
  1.3 Highway Coupler Unit
2 Data Encoding and Signalling
  2.1 Data Encoding
  2.2 End of Message Encoding
  2.3 Signalling
  2.4 Suppression of Reception
  2.5 Terminal Unit Fail-safe
  2.6 Highway Controller Data Encoding and Signalling
3 Message Formats
  3.1 Field and Bit Numbering
  3.2 Start of Message Field
  3.3 Error Check Field
  3.4 Classes of Message
      3.4.1 Control Messages
      3.4.2 Information Messages
  3.5 Control Message Formats
  3.6 Information Message Formats
      3.6.1 Common Fields
      3.6.2 Differing Fields
4 Highway Protocols
  4.1 General Rules
      4.1.1 Freedom to Transmit
      4.1.2 Message Timing
      4.1.3 Modulo 256 Calculations
      4.1.4 Polling Sequence
      4.1.5 Message Numbering Initialisation
      4.1.6 Data Starvation and Surfeit
  4.2 Terminal Unit Response to Polls
      4.2.1 Output Messages
      4.2.2 Verification of Output
  4.3 Terminal Unit Response to Other Control
      Messages
  4.4 Terminal Unit Response to Information
      Messages
      4.4.1 Data Messages
      4.4.2 Block Messages
  4.5 Terminal Unit Recording and Use of Transmit
      Message Numbers
      4.5.1 Recording of Transmit Message
            Numbers
      4.5.2 Calculation and Use of Not
            Acknowledge
      4.5.3 Initialisation of the value of Not
            Acknowledge
 4.6 Highway Controller Actions
     4.6.1 Examination of the Response to a Poll
     4.6.2 Highway Controller Use of the Not Acknowledge
           Field
     4.6.3 Message Recovery Sequence
     4.6.4 Erroneous or NO Response to a Poll
     4.6.5 Completion of Action
Figure 2.1 Bit and Signal Encoding
Figure 2.2 Signalling Waveforms
Figure 2.3 Control Message Formats
Figure 2.4 (a) Information Message Formats: Broadcast
               Data Message
Figure 2.4 (b) Information Message Formats: Point to
               Point Data Message
Figure 2.4 (c) Information Message Formats: Sub Block
               Message
Figure 2.4 (d) Information Message Formats: Block
               Residue Message
SECTION C: THE TERMINAL UNIT/SUBSYSTEM
           INTERFACE SPECIFICATION
1 The Shared Data Areas
  1.1 The Primary Table
      1.1.1 Fields Relating to Received Data
            Messages
      1.1.2 Fields Relating to Transmitted Data
            Messages
      1.1.3 Highway Number
      1.1.4 Error Indications
      1.1.5 Fields Relating to Reception of Block Transfers
  1.2 The In Table and the Out Table
      1.2.1 The In Table
      1.2.2 The Out Table
      1.2.3 Fields in Input and Output Buffers
2 Protocols for the Use of Shared Data Areas
  2.1 Transmission of Data Messages
      2.1.1 Location of a Free Output Buffer
      2.1.2 Loading the Output Buffer
      2.1.3 Output Action by the Terminal Unit
  2.2 Reception of Data Messages
      2.2.1 Input Action by the Terminal Unit
      2.2.2 Reading the Input Buffer
  2.3 Use of the Interrupt Masks
  2.4 Outgoing Block Transfers
      2.4.1 Setting up to Receive a Block
      2.4.2 Input Action by the Terminal Unit
  2.5 Incoming Block Transfers
      2.5.1 Setting Up to Receive a Block
      2.5.2 Input Action by the Terminal Unit
  2.6 Control of the Terminal Unit
Figure 3.1.1 Specification of Shared Data Areas
Figure 3.1.2 Specification of Shared Data Areas
Figure 3.2.1 Primary Table Store Map
Figure 3.2.2 Input Table Store Map
Figure 3.2.3 Output Table Store Map
APPENDICES
APPENDIX A
Redundancy of Highway Control Function
1 General
2 Polling of Passive Highway Controller
3 Active/Passive Status the Highway Controller
4 Activation of Highway Controller
5 Highway Controller Obligations on Becoming
  Active
6 Pre-transmission test by the Active Highway
  Controller
7 Activation of Passive Highway Controller
APPENDIX B
Redundancy of Highway Cabling
1 General
2 Rules for Line Selection
3 Timing of Line re-selection
4 Line Testing
5 Multiple Line Connection
6 Repolling limit
  Resetting limit
APPENDIX C
Optional Control Messages
1 Resetting of Terminal Units
  1.1 The Reset Message
  1.2 Reset Message Format
  1.3 Terminal Unit Response to a Reset Message
  1.4 Passive Highway Controller Response to Reset Messages
  1.5 Highway Controller Use of Reset Messages
      1.5.1 Resetting limit
      1.5.2 Completion of Action
      1.5.3 Procedure of Reactivating a Locked Out Terminal Unit
2 Unnumbered Control Message
  2.1 Format of the Unnumbered Control Message
  2.2 Timing of the Unnumbered Control Message
  2.3 Reception of the Unnumbered Control Message
  2.4 Use of Categories
  2.5 Time Synchronisation Message Format
  2.6 Format of System time
  2.7 Format of Time of Day
  2.8 Format of Ordinal Day
  2.9 Reserved Bits
Figure C.1 Format of Reset Message
Figure C.2 Format of Unnumbered Control Message
Figure C.3 Format of Time Synchronisation Message
APPENDIX D
The Terminal Unit Interface for Time Synchronisation Messages
1 General
2 The In Time Field
3 In Time Available Field
4 Interrupt on Time Reception
Figure D.1 Specification of the Primary Table Extension
Figure D.2 Store Map of Primary Table Extension
APPENDIX E
Broadcast Block Messages
1 General
2 Broadcast Block Format
3 The Subsystem Interface to Broadcast Block Messages
  3.1 Output of Broadcast Block Messages
  3.2 Reception of Broadcast Block Messages
4 Selection of Broadcast Blocks
APPENDIX F
Terminal Unit Output Inhibit
1 General
APPENDIX G
Examples of suitable Cables and Connectors
1 General
2 Cables
3 Connectors

Specifies design of ASWE Serial Highway, information for design and construction of highway terminal unit and interface between terminal unit and computer in subsystem it serves, mainly at software level.