SSP_41151-Appendix_D-RevH.docx

SSP 41151 Apendix D Revision H

UNITED STATES ON-ORBIT SEGMENT TO

JAPANESE EXPERIMENT MODULE INTERFACE REQUIREMENTS DOCUMENT APPENDIX D SOFTWARE INTERFACES

International Space Station Program

Revision H

August 2016

EAR 99. This document contains data within the purview of the U.S. Export Administration Regulations (EAR), 15 CFR 730-774, and is export controlled. The document may be used only in the International Space Station (ISS) program to fulfill responsibilities of the Parties or of a Cooperating Agency of an ISS Partner in furtherance of the ISS Intergovernmental Agreement. Re-transfer or disclosure to, or use by, any persons other than citizens of ISS Program International Partner countries, or use for any other purpose, requires prior U.S. Government authorization.

National Aeronautics and Space Administration International Space Station Program Johnson Space Center Houston, Texas Contract No.: NNJ12GA46C

SSP 41151-Appendix D Revision H

REVISION AND HISTORY

As of Rev. E, Appendix D was split from the main document and will be released and tracked separately due to different Approval Requirements.

This revision incorporates the following DCNs associated with the appropriate SSCNs.

DCN 072 PER SSCN 007351

DCN 086 PER SSCN 007351

DCN 087 PER SSCN 007351

DCN 088 PER SSCN 007351

DCN 094 PER SSCN 007351

DCN 099 PER SSCN 007351

This version incorporates the following DCNs and associated SSCNs

DCN 0115 PER SSCN 008781

DCN 0118 PER SSCN 008781

DCN 0119 PER SSCN 008781

DCN 0120 PER SSCN 008781

DCN 0122 PER SSCN 008781

DCN 0125 PER SSCN 008781

This version incorporates the following DCNs and associated SSCNs

DCN 0123 PER SSCN 010904

DCN 0129A PER SSCN 010904

DCN 0131 PER SSCN 010904

DCN 0134A PER SSCN 010904

This version incorporates the following DCNs and associated SSCNs

DCN 0141 PER SSCN 15485

DCN 0142 PER SSCN 15485

DCN 0147 PER SSCN 15485

DCN 0159 (approved as Rev A) PER SSCN 15485

DCN 0161 PER SSCN 15485

SSP 41151 Appendix D Revision H

PREFACE

UNITED STATES ON-ORBIT SEGMENT TO JAPANESE EXPERIMENT MODULE INTERFACE REQUIREMENTS DOCUMENT APPENDIX D SOFTWARE INTERFACES The contents of SSP 41151, United States On-orbit Segment (USOS) To Japanese Experiment Module Interface Requirements Document Appendix D, Software Interfaces, equally applies to National Aeronautics and Space Administration (NASA) and Japanese Aerospace Exploration Agency (JAXA). This document is under the control of the Space Station Control Board. Any changes or revisions will be jointly agreed to and signed by NASA and JAXA.

INTERNATIONAL SPACE STATION PROGRAM

UNITED STATES ON-ORBIT SEGMENT TO JAPANESE EXPERIMENT MODULE INTERFACE REQUIREMENTS DOCUMENT APPENDIX D SOFTWARE INTERFACES

CONCURRENCE

AUGUST 2016

i

TABLE OF CONTENTS

TABLE

FIGURE

a b c

Appendix d

D.1.0 INTRODUCTION

D.1.1 PURPOSE & SCOPE

The purpose of this appendix is to provide definition of the software interface requirements between the Space Station Manned Base (SSMB) and the Japanese Experiment Module (JEM). The scope of this appendix is limited to the software interfaces between the SSMB End Item and the JEM.

D.1.2 system description The software interface between the SSMB and the JEM is primarily an interface between the Station Management and Control (SMC) end item, on the SSMB side of the interface, and the software components within the JEM. The purpose of the SMC is to provide vehicle level input and control to achieve the operations which accomplish the mission of the Space Station as an element of the United States On-orbit Segment (USOS). The SMC controls the operation of the on-orbit vehicle portion of the Space Station by establishing vehicle level modes, executing vehicle level operations, processing and routing video signals, and management of audio channels. The SMC also controls the distribution of data from the on-orbit vehicle to the ground or external vehicles, from the ground or external vehicles to the appropriate functional area on the on-orbit vehicle, and between functional areas on the vehicle. The SMC also establishes the control and processing for commands from the on-board crew.

SSP 41151 Apendix D Revision H

C1-1

D.2.0 Documents D.2.1 applicable documents None D.2.2 reference DOCUMENTS The following documents are referenced in this Appendix for context and user convenience.

D2-2

D.3.0 INTERFACE REQUIREMENTS

This section of this appendix contains the functional interface requirements for the SMC End Item and the Computer Software Configuration Items (CSCIs) and Hardware Configuration Items which interface with SMC, and which are contained within the JEM. Parameters for each functional interface, as well as design constraints, will be specified.

D.3.1 INTERFACE identification The SMC software consists of the Command and Control (C&C) CSCI and the Portable Computer System (PCS) CSCI. The SMC software interfaces are implemented via the Control Buses (CBs). The SMC software interfaces with components within the JEM are shown in Figure D.3.1-1, Station Management and Control/JEM Software Interfaces.

FIGURE D.3.1-1 STATION MANAGEMENT AND CONTROL/JEM SOFTWARE INTERFACES

This document contains the interface requirements for the SMC software interfaces to the following components contained within the JEM: Common Berthing Mechanism (CBM) JEM, JEM Remote Manipulator System (RMS), JEM Control Processor (JCP), and the JEM Data Interface Unit-III.

Section D.3 identifies and defines all logical and functional interfaces, which have to be mapped on and be in accordance with the physical interfaces specified in 3.2.2.2 of SSP 41151.

The logical interface is the collection of standards and protocols which are used to communicate via the appropriate physical interface.

The logical interfaces are described in section D.3.3 together with the protocols implemented on the physical interfaces (e.g. for the MIL STD 1553 bus the Bus Controller (BC) and the Remote Terminal (RT)). The Software (SW) interfaces relevant to section D.3.3 are (see also Figure D.3.1-2, SSMB to JEM SW Related Data Interfaces):

Data Interface Unit-III Interface(ISS C&C Bus) SSMB/JEM System Bus Interface (ISS C&C Bus) Remote Manipulator System Interface (ISS C&C Bus) Common Berthing Mechanism Interface (ISS C&C Bus) There are basically two types of logical interfaces:

interfaces for transferring data packets between two directly connected nodes (Node-to-Node Logical Interface) interfaces for transferring data packets end to end (End-to-End Logical Interface) The MIL-STD-1553B data exchange interface falls into the first category. It describes mainly how packets are transferred from node to node using the MIL STD 1553B basic services. This first category interface is described in section D.3.3.1.

The Consultative Committee for Space Data Systems (CCSDS) protocols fall into the second category where the contents of the headers allow end to end routing and identification of the purpose and content of the packet to the end destination. This second category interface is described in section D.3.3.2.

The functional interface is the description of the commands and data which must be passed between two software applications for those applications to perform properly. These commands and data are passed via the physical interfaces using the standards and protocols of the logical interfaces. (N.B. Multiple functional interfaces may be associated with a single physical interface, and multiple logical interfaces may also be associated with a single physical interface.)

See Figure D.3.1-3, Physical, Logical and Functional Interfaces Relationship, for illustration of this concept.

FIGURE D.3.1-2 SSMB to JEM SW Related Data Interfaces

FIGURE D.3.1-3 PHYSICAL, LOGICAL AND FUNCTIONAL INTERFACES RELATIONSHIP

D.3.2 CONCEPT OF OPERATION

All buses operate independently. Bus controllers for the busses within the JEM provide the command, control, and servicing of the remote terminals on their bus. The CBs provide the information collection and redistribution functions for information to be transferred or shared between components on different Local and/or User Buses when the task cannot be accomplished by the bus controllers of the lower levels of the hierarchy.

D.3.2.1 FRAME STRUCTURE

The software control concept for the MIL-STD-1553B buses on the International Space Station (ISS) uses cyclic, synchronized, time-scheduled communications based on a 10 Hz (100 ms) Command and Data Handling (C&DH) Processing Frame, as shown in Figure D.3.2.1-1, Frame Concept. The 100 ms C&DH Processing Frame is made up of an 80 Hz (12.5 ms) Multiplexer/Demultiplexer (MDM) Input/Output (I/O) Subframe, which supports a higher level architecture featuring a 1 Hz (1 sec) C&DH Minor Frame consisting of 10 Processing Frames, and a 0.1 Hz (10 sec) C&DH Major Frame consisting of 10 Minor Frames.

This concept provides a fixed, task scheduling environment featuring fixed-format 1553 bus transactions, including subsystem I/O and telemetry data transfers. The fixed processes is table driven. A representation of the 100 ms frame with an example of bus allocations (NOT the actual allocations, which are design implementation) is shown in Figure D.3.2.1-2, Bus Time Division Allocations (Example).

FIGURE D.3.2.1-1 FRAME CONCEPT

FIGURE D.3.2.1-2 BUS TIME DIVISION ALLOCATIONS (EXAMPLE)

D.3.3 LOGICAL INTERFACE REQUIREMENTS

D.3.3.1 NODE TO NODE LOGICAL INTERFACE

This section describes the JEM to SSMB protocol for transferring data across the MIL-STD- 1553 busses by defining protocol options, specific features and special use of bus capabilities.

D.3.3.1.1 MESSAGE FORMAT

The MIL-STD-1553 bus implementing the command and data interface is controlled at any given time by one BC on the SSMB side, with all other units on the bus operating as Remote Terminals (RTs).

The BC will always initiate the information transfers on the bus.

The following categories are defined for the information transfer:

Point to Point Communication Controller to RT Transfer RT to Controller Transfer Mode Command without (w/o) Data Word Mode Command with Data Word Broadcast Communication Controller to RT Transfer Mode Command without (w/o) Data Word Mode Command with Data Word

D.3.3.1.2 MODE CODES

Remote terminals located within the JEM, which are connected to MIL-STD-1553B busses controlled by bus controllers located within the SSMB shall implement the mode codes (as defined by MIL-STD-1553B, Notice 2) in accordance with Table D.3.3.1.2-1, JEM Implemented Mode Codes.

TABLE D.3.3.1.2-1 JEM IMPLEMENTED MODE CODES (2 Pages)

In case of reception of reserved or not-implemented mode codes, remote terminals located within the JEM shall respond as follows:

Dynamic Bus Control Respond with Status Word. The DYNAMIC BUS CONTROL ACCEPTANCE bit in the status word will not be set.

Transmit Vector Word Respond with Status Word plus a single Data Word.

Selected Transmitter Shutdown Respond with Status Word. No transmitters are shut down as a result of this mode code.

Override Selected Transmitter Shutdown Respond with Status Word. No transmitters that have been previously shut down are reactivated as a result of this mode code.

Reserved Mode Codes (T/R Bit = 1: 01101 - 01111) Respond with Status Word.

Reserved Mode Codes (T/R Bit = 1: 10110 - 11111) Respond with Status Word plus a single Data Word.

Reserved Mode Codes (T/R Bit = 0: 10110 - 11111) Respond with Status Word.

Invalid Mode Codes (T/R Bit = 0: 00000 - 10000, 10010 - 10011) No response.

Invalid Mode Codes (T/R Bit = 1: 10001, 10100 - 10101) No response.

D.3.3.1.3 status word Remote terminals located within the JEM which are connected to MIL-STD-1553B busses controlled by bus controllers located within the SSMB shall implement the 1553 status word (as defined by MIL-STD-1553B, Notice 2) in accordance with Table D.3.3.1.3-2, JEM Implemented Status Word Bits.

TABLE D.3.3.1.3-2 JEM IMPLEMENTED STATUS WORD BITS

The C&C MDM shall neglect ‘Terminal Flag Bit’ within the status word transmitted within JEM components.

D.3.3.1.4 BUS FAILURE DETECTION AND RECOVERY

The C&C MDM within the SSMB performs bus Failure Detection, Isolation, and Recovery (FDIR) functions to detect communication errors within JEM components, to isolate faulty parts, and to recover communication within JEM components.

Remote terminals located within the JEM, which are connected to MIL-STD-1553B busses controlled by the C&C MDM located within the SSMB, shall support the C&C MDM bus FDIR by transmitting the status word described in section D.3.3.1.3.

The C&C MDM bus FDIR consists of the following items:

Failure detection and isolation Failure recovery Supplementary data downlink Frame counter D.3.3.1.4.1 Failure Detection and Isolation D.3.3.1.4.1.1 Failure detection The primary C&C MDM shall monitor ‘transaction error’. Transaction error is one of the following conditions:

Response timeout Message error bit in status word Message violating MIL-STD-1553 format Frame counter fails to change D.3.3.1.4.1.2 Failure ISOLATION The primary C&C MDM shall differentiate the following fault cases:

Failure of each RT/channel Failure of each bus channel Failure of individual RT Failure of each RT/channel is determined when two or more consecutive transaction errors are detected on primary channel with an individual RT.

Failure of each bus channel is determined when two or more consecutive transaction errors are detected on primary channel with multiple RTs.

Failure of an individual RT is determined after primary RT/channel failure has been declared, when a second consecutive transaction error is detected on the back-up channel of the same individual RT.

D.3.3.1.4.2 failure recovery The Primary C&C MDM shall take the following actions to support failure recovery:

In case of 1553 Transaction Error:

The Primary C&C MDM performs retry of failed message only when the failed message is of the type ‘BC to RT Cmd Xfer’, ‘RT to BC Cmd Xfer’ and ‘Data Load’ described in section D.3.3.1.5. Other failed messages are discarded.

Retry shall be performed at the next ‘BC to RT Cmd Xfer’ boxcar which is allocated to the RT.

In case of failure of each RT/channel:

The Primary C&C MDM switches the channel to the backup channel for communication with all RTs. The channel switch shall be performed within two major I/O frames (20 sec).

If the failed RT/channel is already the backup channel, the C&C MDM shall declare a failure of the RT as described in the following paragraphs. (Note: Even though the failed RT may not have a failed Primary Channel, the rationale is to prevent a second bus switchover. If the function of the failed RT is required, the crew/ground can command a switchover to the primary channel, after disabling the FDIR response for the failed RT on the primary channel.)

In case of failure of an individual RT:

The Primary C&C MDM reconfigures the RT to redundant RT if applicable. RT reconfiguration scenario for JEM components is uniquely defined as follows:

JCP reconfiguration The following two cases are defined as the failure of the JCP:

Communication loss on both channels as defined in section D.3.3.1.4.1.2 Failure to increment the frame counter as defined in section D.3.3.1.4.5 The reconfiguration scenario for the JEM is described in section D.3.4.2.3.

Data Interface Unit (DIU)-III reconfiguration None (Reconfiguration with respect to JEM activation is described in section 3.4.)

RMS reconfiguration None If the failed RT is already the redundant RT or after reconfiguration communication is not established with the redundant RT, the C&C MDM shall initiate its retry logic for the RT. Retry logic for JEM components is defined in section 3.4.

In case of failure of both bus channels:

The C&C MDM reconfigures the C&C MDM configuration.

D.3.3.1.4.3 deleted

D.3.3.1.4.4 SUPPLEMENTARY DATA DOWNLINK

For further investigation on the ground, the following data shall be made available for downlink:

Fault status of each RT/channel pair.

Fault status of each bus channel.

Fault status of each redundant bus.

D.3.3.1.4.5 FRAME COUNTER

The JCP and RMS shall provide a monotonically increasing counter (0 to 99) in the first word of each 10 Hz RT to BC Telemetry Poll. The C&C MDM shall monitor the counter. If the counter fails to change for three seconds, the C&C MDM shall issue a caution event indicating JCP or RMS Failure and initiate the appropriate failure response as defined in section D.3.3.1.4.2.

D.3.3.1.5 1553 DATA EXCHANGE

This section provides the specifications for data exchange.

D.3.3.1.5.1 BROADCAST SYNC

FUNCTION:

Some remote terminals have communications with the bus controller which is dependent upon the processing frame number. This means that although the same remote terminal address and subaddress is used in different processing frames, the definition of the data contained in the transfer is defined differently (based upon the processing frame number). For frame dependent communications, the processing frame number of remote terminal must be contained in the data provided to the bus controller. (Note: The frame structure used upon the International Space Station (ISS) is described in section D.3.3.1.5.6, RT to BC Telemetry (TLM) Poll) The C&C CSCI operating as bus controller shall broadcast a Synchronize With Data Word Mode Command (Mode Code 10001) at the beginning of the first subframe of each processing frame to subaddress 31. A 5 ms minimum interval shall be maintained between the Broadcast Sync and the next scheduled transmission to the JEM. The data word associated with the Synchronize With Data Word Mode Command transmitted by the bus controller identifies the current processing frame number of the bus controller.

1553B MESSAGE FORMAT:

Broadcast Communication: Mode Command with Data Word

BUS FDIR:

Transaction Error check: NO Retry: NO

DATA WORD FORMAT:

Broadcast Synchronization shall comply with the requirements contained in Table D.3.3.1.5.1-1, Broadcast Synchronize with Data Word Format.

TABLE D.3.3.1.5.1-1 Broadcast synchronize with data word Format

Range

D.3.3.1.5.2 BROADCAST TIME

FUNCTION:

Some remote terminals within the JEM require the synchronization of their Local Reference Clock (LRC) with the local station clock (C&C MDM LRC) to provide a consistent time base across the station resources for correlation of data and events.

The C&C MDM shall broadcast time at a 1 Hz rate to RT subaddress 29.

The C&C MDM shall broadcast time as the first bus transaction of the third subframe following a 1 sec crossover. The C&C MDM appends the non-CCSDS seconds/subseconds data to the time value in its LRC to build the Time Broadcast message. The first four words of the time data are in the CCSDS Calendar Segmented Code format. These words consist of Binary Code Decimal (BCD) formatted time fields. The fifth and sixth words contain binary subseconds. The seventh word contains Universal Time Coordinated (UTC) conversion parameters but, in the implementation, it is unused. The eighth word is a non-CCSDS field which contains seconds and subseconds information. The Time Broadcast should represent the actual C&C MDM time at the time of the broadcast.

The RT should compensate for a transport Lag of 180 microseconds. (Transport Lag is the time delay incurred during the transmission and receipt of the broadcast. This is a constant value for each RT.)

1553B MESSAGE FORMAT:

Broadcast Communication: Controller to RT Transfer

BUS FDIR:

Transaction Error check: NO Retry: NO

DATA WORD FORMAT:

Broadcast Time shall comply with the requirements contained in Table D.3.3.1.5.2-1, Broadcast Time Format.

TABLE D.3.3.1.5.2-1 Broadcast TIME Format (2 Pages)

Range

D.3.3.1.5.3 BROADCAST ancillary data

Ancillary data is information which is disseminated between large numbers of components within the ISS. Ancillary data is distributed by the bus controller broadcasting the information over the bus. The definition of the information contained within the ancillary data is dependent upon the processing frame in which the information is transmitted.

The C&C CSCI operating as bus controller shall broadcast ancillary data at a 10 Hz rate to RT subaddresses 13 and 14. Ancillary data is defined in section D.3.4. Remote terminals in the JEM which need to receive ancillary data shall synchronize communications with the bus controller as defined in section D.3.3.1.5.1.

characteristics:

The broadcast ancillary data shall be separated from the synchronize with data mode command by a minimum of 5 ms.

The data contained in each 64-word message set (2 boxcars) shall be grouped into 10 Hz, 1 Hz, and 0.1 Hz segments. The boundaries of each rate group shall be fixed within the 2 boxcar set at the same location in each processing frame.

1553B MESSAGE FORMAT:

Broadcast Communication: Controller to RT Transfer

BUS FDIR:

Transaction Error check: NO Retry: NO

DATA WORD FORMAT:

Broadcast Ancillary Data shall comply with the requirements contained in Table D.3.3.1.5.3-1, Broadcast Ancillary Data Word Format.

TABLE D.3.3.1.5.3-1 Broadcast ANCILLARY Data WORD Format

Message 1

Message 2

D.3.3.1.5.4 BC to RT Command Transfer

Standard Commands conveyed by BC to RT transfer boxcars are the primary means of control of the station. Standard commands can originate in the Ground Segment and appear on the C&C MDM CSCI interface from the Assembly/Contingency Baseband Signal Processor. Alternatively, standard commands can originate in the PCS as a crew input, or from the Space Shuttle via the Orbiter Interface Unit on a direct ISS bus connection, or the Space to Space Station Radio interface. Standard commands can also originate in the C&C MDM, for transmission to a local bus remote terminal for processing or route to a user bus remote terminal. The C&C MDM shall validate command in accordance with section D.3.3.2.2.2.

For the JEM interfaces, two types of standard commands are defined. One is the command with CCSDS Header described in section 3.3.2.1, destined for the JCP and RMS. The other is the command without CCSDS Header, destined for the DIU-III and CBM.

characteristics:

Commands to JEM components can be composed of one or two MIL-STD-1553 messages.

Commands to the DIU-III and CBM shall be one message of 32 words or less in a non-CCSDS format.

Commands to JCP and RMS shall be two messages, even if the length of command is less than one message in CCSDS format The two 1553 messages of two-message commands shall come to JCP within one processing frame, and shall come to consecutive subaddresses.

Command transmission from the C&C MDM to JEM JCP, RMS and DIU-III shall be a maximum one message per one second. (i.e. max. 1 Hz) (Note: Command transmission from C&C MDM to DIU-III shall be in 6th Boxcar in 2nd subframe (subframe #1) in 2nd processing frame (processing frame #X1: X=0,1,2...9) of minor frame.)

Commands transmission from the C&C MDM to the JEM CBM shall be a maximum of ten commands per one second (i.e., 10 Hz).

BC to RT Command Transfer shall occur only when there is a Command to be transmitted.

If one message of a two-message command fails, both of the messages shall be retried at the next boxcars.

***Due to the design of the United States (US) uplink capability, commands with a length of 48 of less octets will be zero padded between the last command word and the checksum prior to uplink.

1553B MESSAGE FORMAT:

Point to Point Communication: Controller to RT Transfer

BUS FDIR:

Transaction Error check: YES Retry: YES

DATA WORD FORMAT:

The CCSDS Format Command shall comply with the requirements in Table D.3.3.1.5.41, CCSDS Command Data Word Format. The Non-CCSDS Format Commands for the DIU-III shall comply with the requirements in Table D.3.3.1.5.4-2, Non-CCSDS Format Commands Data Word Format: DIU-III.

TABLE D.3.3.1.5.4-1 CCsDS Command data word format

Message 1

(defined in section D.3.3.2.1) 0-15

(defined in section D.3.3.2.1) 0-15

(defined in section D.3.3.2.3 or section D.3.4) 0-15

Message 2

(##+2)-

* Checksum is in last word of the command packet as defined by the packet length parameter in the CCSDS primary header.

TABLE D.3.3.1.5.4-2 Non-ccsds format Commands data word format:DIU-III

(defined in section D.3.4.3.1.1) 0-15

0-15

* The number of Data Words (N) is not fixed to 32 but variable depending on the length of Command Parameter field. For a command with no parameter, the Command Parameter field doesn’t reside, and the number of Data Word is one.

D.3.3.1.5.5 RT TO BC COMMAND TRANSFER

Standard Commands conveyed by RT to BC command transfer boxcars that support the File Transfer Upload and Download protocols defined in section D.3.3.2.3. The C&C MDM shall validate all commands.

CHARACTERISTICS:

The two 1553 messages of two-message commands shall come from the JCP, Management Data Processor (MDP) or Back-up Controller (BUC) within one processing frame, and shall come from consecutive subaddresses.

Commands from the JEM JCP, MDP or BUC shall be a maximum one command per one second. (i.e., maximum command rate of 1 Hz) Command polls from the C&C MDM to JEM JCP, MDP or BUC shall be retried during the next processing frame to account for transmission errors. (i.e., C&C polls for commands at a maximum rate of 2 Hz) If one message of a two-message command fails, both messages of the command shall be retried.

Duplicate command will not be processed (a duplicate command is defined as a command which has the same Application Process Identification (APID) and sequence count as the command received previously).

1553B MESSAGE FORMAT:

Point to Point Communication: RT to BC Transfer

BUS FDIR:

Transaction Error check: YES Retry: YES

DATA WORD FORMAT:

The Command shall comply with the requirements in Table D.3.3.1.5.5-1, Command Data Word Format.

TABLE D.3.3.1.5.5-1 COMMAND DATA WORD FORMAT

(defined in section D.3.3.2.1) 0-15

(defined in section D.3.3.2.1) 0-15

(defined in section D.3.3.2.3) 0-15

Note: JEM shall set the Legal Station Modes word to a constant value which indicates that the command is legal in all modes.

D.3.3.1.5.6 RT TO BC TLM POLL

The RT to BC TLM Poll is the method used to transfer data from the JEM to the C&C MDM for its use as well as for transmission to other users. In each Processing Frame, the JCP shall be allocated 3 boxcars for RT to BC communication. Either DIU-III(A) or (B) shall be allocated 9 boxcars in each Minor Frame when the JCP is not activated. The JEM RMS shall be allocated 2 boxcars in each Processing Frame. The JEM CBM shall be allocated 2 boxcars in each Processing Frame.

CHARACTERISTICS:

The contents of the JCP poll shall include normal health and status, Caution and Warning (C&W), JEM message, command response, command response counter, file and memory transfer status, and frame counter.

The contents of the JEM RMS poll shall include normal health and status, command response, command response counter, file and memory transfer status, frame counter, Guidance, Navigation and Control (GNC) Data and split screen configuration commands.

The C&C Processor shall use frame counter data from the JCP and JEM RMS to determine that each main processor is functioning. The frame counters indicate the current processing frame number. When the JCP or the JEM RMS is synchronized with the C&C MDM, the processing frame number shall be the same as the C&C processing frame number transmitted in the synchronize with data mode code.

The C&C Processor shall use the file and memory transfer status data in conjunction with the file and memory transfer function. The characteristics of the file and memory transfer status data are contained in paragraph D.3.3.2.3.1.2.4.

The frame counter, and file and memory transfer status data, shall be transmitted in the first data word of the first RT to BC TLM Poll boxcar in each Processing Frame.

The data from the JCP contained in each 96-word message set (3 boxcars) and the data from the JEM RMS contained in each 64-word message set (2 boxcars) shall be grouped according to the update rate of the data. The data shall be grouped in 10 Hz, 1 Hz, and 0.1 Hz segments. The boundaries of each rate group shall remain fixed within the boxcars at the same location in each processing frame. Data items with update rates other than the 10 Hz, 1 Hz, and 0.1 Hz groups should be included in the next lower rate group and repeated a required to achieve the desired update rate; for example, 0.5 Hz data shall be placed in the 0.1 Hz rate group, and 5 samples shall be allocated within the rate group for each 0.5 Hz data item over the 10 second major frame.

The C&C MDM shall use the frame counter to identify the unique content of the RT to BC TLM Poll data.

The JCP and JEM RMS shall increment the command response counter to identify that the command response(s) in the command response fields have been updated. The command response counter shall be incremented by the number of new command responses. When the command response counter is incremented by one (1), the new command response shall be stored in the ’Latest Command Response’ field. When the command response counter is incremented by more than one, both the ’Latest Command Response’ and ’Second Latest Command Response’ shall contain updated command responses.

The content of the DIU-III poll shall include normal health and status only, and does not include any of the command response, command response counter, File and Memory Transfer (FMT) status, or frame counter.

1553B MESSAGE FORMAT:

Point to Point Communication: Controller to RT Transfer

BUS FDIR:

Transaction Error check: YES Retry: NO

DATA WORD FORMAT:

Each message in each message set of the JCP poll and JEM RMS poll shall comply with the requirements in Table D.3.3.1.5.6-1, RT to BC TLM Poll Data Word Format: JCP and JEM RMS. The first words of the 1Hz Normal Health and Status (H&S) of the first message in each minor frame shall contain the information shown in Table D.3.3.1.5.6-2, Definition of First 9 Words of 1Hz Data: JCP and JEM RMS.

Each message of the DIU-III poll shall comply with the requirements in Table D.3.3.1.5.6-3, RT to BC TLM Poll Data Word Format: DIU-III.

TABLE D.3.3.1.5.6-1 RT TO BC TLM POLL DATA WORD FORMAT: jcp and jem rms

Message 1

(defined in section 3.4) if required 0-15

(defined in section 3.4) 0-15

TABLE D.3.3.1.5.6-2 DEFINITION OF FIRST 9 WORDS OF 1Hz DATA: jcp and jem rms

*** Command Response Counter is a cyclic counter and its initial value is (0).

TABLE D.3.3.1.5.6-3 rt to bc tlm poll data word format: diu-iii

(defined in section D.3.4) 0-15

D.3.3.1.5.7 Data Load

Data load provides the mechanism for transferring disk file data from the C&C MDM to the JEM (File Load). On each ISS Control Bus (CB), nine boxcars are allocated in each processing frame to perform this function. Only one BC to RT transfer is supported at a time.

1553B MESSAGE FORMAT:

Point to Point Communication: Controller to RT Transfer bus fdir:

Transaction Error check: YES Retry: YES

CHARACTERISTICS:

All information required for processing a Data Load packet is contained within the packet.

Each Data Load transaction shall be treated as a complete transaction.

File Load packets shall be transferred at a maximum rate of 10 Hz.

A message shall be transmitted to all data load subaddresses even when the actual data load packet is smaller.

File Load packets shall be formatted as described in paragraph D.3.3.2.3.1.2.6.

If a message out of nine messages fails, all nine messages shall be retried in the next processing frame. The retry shall be performed two times at the most (the same command shall be sent three times).

D.3.3.1.5.8 memory DumP

FUNCTION:

Memory dump provides the mechanism for directly dumping all or part of the addressed applications memory area. On each ISS CB, three boxcars are allocated in each processing frame to perform this function. Only one RT to BC transfer is supported at a time.

Note: Memory dump function is not applicable for BUC

1553B MESSAGE FORMAT:

Point to Point Communication: RT to Controller Transfer

BUS FDIR:

Transaction Error check: YES Retry: No

CHARACTERISTICS:

Memory Dump is a continuous function. Once initiated, the selected memory area shall be cyclically dumped for the MDP until commanded to dump a different memory area, and for the JCP until commanded to terminate.

Memory Dump packets shall be transferred at a rate of 10 Hz.

Memory Dump packets shall be formatted as described in paragraph D.3.3.2.3.4.3.

Memory Dump packets shall be polled from all of the ’96 Word Memory Dump’ subaddresses during each transfer.

D.3.3.1.5.9 DATA DUMP

FUNCTION:

Data dump provides the mechanism for transferring a file from the JEM to the C&C MDM Mass Storage Device (MSD) for subsequent transfer to the ground (File Dump). Nine boxcars are allocated on the ISS CB in each processing frame to perform this function. Only one RT to BC transfer is supported at a time.

1553B MESSAGE FORMAT:

Point to Point Communication: RT to…