SSP_50469-RevD-Retired.docx

OPERATIONS CONTROL SOFTWARE (OCS) TO ROBOTIC WORKSTATION (RWS)

INTERFACE CONTROL DOCUMENT (ICD)

International Space Station Program

Revision D Retired

April 2017

Type 1 NASA APPROVED

National Aeronautics and Space Administration International Space Station Program Johnson Space Center Houston, Texas Contract No.NNJ09GA18B

REVISION AND HISTORY PAGE

Includes SPAR 830360 and PIRNS 1A, 2A, 3, 4B, and 5 to Spar 830360 11-01-99

Revision A incorporates the following approved PIRNs: 0001, 0002B, 0005B, 0006, 0008, 0011, 0012C, 0013C, 0014C, 0016A, and 0017.

Retired

Revision B incorporates the following approved PIRNs: 0003E, 0007E, 0018, 0019, 0020, 0021, and 0022.

PIRNs Withdrawn: 0004, 0009, 0010, and 0015

Revision C incorporates the following approved PIRNs: 0023, 0024, 0025, 0026, 0027, 0028, 0029, 0030, and 0031

Revision C incorporates the following approved SSCNs:

9664, 10039, 10045, 12359, 8225, 8649, 9004, 9744, 10726, 11586, 12505, 8490, 8652, 9005

Revision D incorporates the following approved PIRNs: 0032A, 0033, and 0034 Revision D Incorporates the following approved SSCNs: 13427 and 14129 09-19-17

Per SSCD 15639, Revision D is being released in its entirety due to incorporation of approved PIRNs and will be available in the program repository for future reference.

Retired

SSP 50469, Revision D April 2017

RETIRED

SSP 50469, Revision D RETIRED April 2017 iii x

INTERNATIONAL SPACE STATION PROGRAM

OPERATIONS CONTROL SOFTWARE (OCS) to ROBOTIC WORKSTATION (RWS) INTERFACE CONTROL DOCUMENT (ICD)

LIST OF CHANGES

All changes to paragraphs, tables, and figures in this document are shown below:

Table 3.3.4-1

Table 3.3.3-6

Retired

Table 3.2.3.1-1

Table 3.3.3-7A

Table 3.3.3-7B

Table 3.3.3-2F

Table 3.3.3-6

Table 3.3.3-7

Table 3.3.3-6

3.3.3

Table 3.3.1-1

Table 3.3.3-4

Table 3.3.3-7B

LIST OF CHANGES

009177

2.1

2.2

3.1.1

3.3.3.2

Appendix A

Figure 3.1.1-1

Figure 3.1.1-2

Table 3.2.3.1-1

Table 3.2.3.1-2

Table 3.3.3-2A, 2B, 2C, 2E

Table 3.3.3-5

Retired

Table 3.3.3-6

Table 3.3.4-1

3.3.3.2

Figure 3.3.3-1

Table 3.2.3.1-1

Table 3.3.3-2C

Table 3.3.3-2E

Table 3.3.3-2E-1

Table 3.3.3-2F

Table 3.3.3-3

Table 3.3.3-3A

Table 3.3.3-3B

Table 3.3.3-6

Table 3.3.3-7

Table 3.3.3-8

Table 3.3.3-9

Table 3.3.3-4

Table 3.3.3-5

Table 3.3.3-6

Table 3.3.3-2E-1

Table 3.3.3-3

Table 3.3.3-3B

Table 3.3.4-1

Table 3.3.3-7

Table 3.3.3-8

LIST OF CHANGES

Table 3.2.3.1-2

Table 3.3.3-2E

Table 3.3.3-2E-1

Table 3.3.3-3B

Table 3.3.3-4

Table 3.3.3-6

Table 3.3.4-1

Table 3.3.3.7A

Retired

3.3.3

5.1

Table 3.2.3.1-2

Table 3.3.3-2c

Table 3.3.3-2e-1

Table 3.3.3-3b

Table 3.3.3-7b

Table 3.3.3-7c

Table 3.3.3-8

013008

Table 3.2.3.1-1

Paragraph 3.2.5.1

Table 3.3.3-2E-2

013008

Table 3.2.3.1-1

Table 3.3.3-2E-2

Table 3.3.3-7C

Table 3.3.4-1

013008

013008

013008

013008

Paragraph 3.2.4.1

Table 3.3.3-2C

Table 3.3.3-2F

Table 3.3.3-10

Table 3.3.4-1

LIST OF CHANGES

013008

Table 3.3.3-7B

013008

013008

Retired

Table 3.3.3-2A

TABLE OF CONTENTS

appendiCes

TABLES

FIGURES

INTRODUCTION

This is a joint interface document between components of the Canadian Space Agency (CSA) sponsored Mobile Servicing System (MSS) program and the National Aeronautics and Space Administration (NASA) sponsored Robotics Work Station (RWS) program.

It describes the interface between the Operations Control Software (OCS) Computer Software Configuration Item (CSCI) developed under the MSS program and the RWS software (including firmware) developed under the RWS program. OCS and RWS interface via a Shared Memory area connected over the backplane in the Control Electronics Unit (CEU). The OCS performs all communications to external entities via the RWS. The OCS and RWS exchange commands, responses, status information, files, and telemetry data over the Shared Memory. These may be communications directly between the OCS and the RWS, or they may constitute information passed through RWS directed to, or received from external entities such as MSS equipment, or other ISS elements via the Systems Management Computer (SMC).

Identification This Interface Control Document (ICD) is identified as the OCS to RWS ICD, SSP 50469.

Scope This document describes the interface between the OCS CSCI and the RWS software. The document provides a basis for deriving requirements for the interfacing CSCI's.

This document describes:Retired

· the physical architecture description of the Shared Memory Interface (SMI) through which all OCS - RWS data transfers occur;

· the communication protocols and message formats for the different types of data exchanged between OCS and RWS;

· the major types of data exchanged between OCS and RWS, their sources, and their destinations;

· the services provided by RWS to OCS, and the commands OCS issues to invoke those services;

· the layout in shared memory for all OCS-RWS message transfers for communications between OCS and all external entities with which OCS communicates, and for communications between OCS and RWS; and

· the co-ordination, timing, and synchronization of access to the SMI by OCS and RWS.

This document does not contain the detailed definitions of the application information exchanged between the OCS and the external equipment with which it communicates. The description of the contents of these messages are described in the following documents:

· the SMC to ISS ICD, SSP 41175, Book 10 for SMC messages;

· the MSS Robotics Control Software (MRCS) to Arm Control Unit (ACU) ICD, SPAR-SS-ICD-1273 for ACU messages;

· MRCS to MBS Control Unit (MCU) ICD, SPAR-SS-ICD-1456 for MCU messages;

· MRCS to SPDM ICD, SPAR-SS-ICD-1957 for Special Purpose Dextrous Manipulator (SPDM) messages;

· MRCS to Arm Control Unit (AVU) ICD, CSA-SS-ID-0002, for AVU messages.

The MSS Local Buses ICD, SPAR-SS-ICD-1148, has also provided a source of information for this ICD.

Document Overview The format of this document is based upon the Software Interface Control Document Template, SPARSSDID1316, which was tailored from the DODSTD2167A. This document is organized as follows:

Definitions The following definitions apply to these words when used in this document:

See the glossary in Appendix A for definitions of technical terms used herein.

1-2

DOCUMENTS

Applicable Documents The following documents of the exact issue are referenced in this document and form a part of this document to the extent specified herein.

DOCUMENT NUMBER TITLE

June 2010

SPAR 830354 Control Electronics Unit Internal Interface ControlRetired

Reference Documents The following documents are for reference only.

DOCUMENT NUMBER TITLE

JSC-37534 Mission Control Centere Generic Command Subsystem Requirements

D684-10056-01 Boeing Software Standards and Procedures Specification (SSPS)

Parent Documents There are no parent documents to this ICD.

2-3

Interface Description This section describes the OCS to RWS interface, including timing and protocols used on the interface.

Interface Overview The following subsections provide a general overview of the system and interface architecture.

System Architecture The CEU of RWS supports three application software CSCI's: Workstation Host Software (WHS), OCS, and Video Graphics Software (VGS). The Master Embedded Controller Board (MECB) and Slave Embedded Controller Board (SECB) of the CEU host the WHS and OCS respectively, as well as separate copies of the CEU firmware CSCI. The MECB provides access to four MIL-STD-1553B interfaces. These are the MSS local bus, the Power and Data Grapple Fixture (PDGF) local bus, one ISS Control Bus-External (CB-EXT) bus, and an RWS local bus. The latter bus communicates with operator interface devices on the Display and Control Panel (DCP), including the Rotational Hand Controller (RHC) and Translational Hand Controller (THC). The MECB interfaces with the SECB via a SMI over the backplane. These interfaces are shown graphically in Figure 3.1.1-1.Retired

OCS can only interface physically with WHS over the SMI. The shared memory resides on the SECB. Through WHS, OCS can interface logically with various external entities in and around the RWS as shown in Figure 3.1.1-2. This figure includes references to the ICD's in which each of these logical interfaces are defined. Note the logical view treats all messages on the CB-EXT Bus as being exchanged with Command and Control Software (CCS), and messages on the RWS Local Bus as being exchanged with WHS. Details of the interface to the CEU hardware can be found in the CEU internal ICD, SPAR 830354.

In order to support the logical interfaces, WHS provides the following services for the OCS:

3-2

FIGURE 3.1.1-1 PHYICAL INTERFACE ARCHITECTURE

FIGURE 3.1.1-2 LOGICAL INTERFACES

Interface Architecture The SECB Random Access Memory (RAM) is mapped to the MECB memory. Although the entire 2 Megabytes is shared, the term SMI applies only to the upper 64 Kbytes. The lower 128 kilobytes is reserved for use by the SECB Firmware. The intervening memory is available for use by the OCS CSCI. The mapping of SECB memory to MECB is shown in Table 3.1.2-1 below.

During normal operation, with OCS loaded and running, the SMI is limited to two 32 Kbytes regions. One region is used for RWS to OCS data transfers, and the other is used for OCS to RWS data transfers. Note that the 64 Kbyte interface is not mapped at the same address locations of the Master and Slave Embedded Controller Boards. In all allocations of messages to shared memory within this ICD, references are always made relative to the start (lowest memory address) of Shared Memory.

Each half of the SMI is partitioned into equal blocks of 32 words. The first five blocks are reserved for the status bits used to control data flow and message length indicators. Each message between OCS and RWS is exchanged on one or more of the 128 subsequent blocks. This allows the message definitions to be changed without impacting the starting location of subsequent messages in memory. Message identifications are based on the number of the first block which the message is allocated to in the SMI. Note that message id's need not be contiguous since messages can span more than one block.Retired

The final 8 Kbytes of the two SMI regions are used for file transfers.

TABLE 3.1.2-1 MECB-SECB ADDRESS MAPPING

( 128 kilobytes ) 0000 0000 to 0001 FFFF

( 64 bytes per block ) 001F 0000 to 001F 013F

( 64 bytes per block ) 001F 0140 to 001F 213F

( 8 kilobytes ) 001F 6000 to 001F 7FFF

( 64 bytes per block ) 001F 8000 to 001F 813F

409F 8140 to 409F A13FRetired

RWS-OCS Message Blocks 0 to 127 ( 64 bytes per block ) 001F 8140 to 001F A13F

( 8 kilobytes ) 001F E000 to 001F FFFF

Interface Requirements This section provides the requirements necessary to implement the RWS-OCS interface.

OCS/SMI Initialization The following requirements apply in order to start-up OCS and initialize communication on the SMI.

a) The RWS software shall load the OCS image into SECB memory starting at address 0002 0000.

b) The RWS software shall transfer the SECB processor control to OCS at execution start address 0002 0010 hex. The transfer mechanism is an internal RWS issue.

c) The RWS software and OCS shall enable hardware memory protection for the SMI. This memory protection prevents each CSCI from writing to the other CSCI's memory outside of the appropriate portion of the SMI.

d) OCS shall send an SMI Sync Response message with OCS_Ready set to “ready” (see Table 3.3.3-1 below) to RWS within 500 msec of receiving control of the SECB processor.

Message Transfer Protocol Each interfacing CSCI has read-only and write-only areas assigned in the SMI. Data in the read-only area is referred to as incoming, and data in the write-only area is referred to as outgoing.

As described in previous section, the shared memory is partitioned into 32 word blocks - five status blocks and 128 message blocks. The incoming status blocks contain Message Available Flags and Message Word Counts which correspond to the 128 incoming message blocks. There are also Message Acknowledge Flags which correspond to the 128 outgoing message blocks. The following requirements apply for each message transferred across the SMI.

Outgoing Message Transfer Requirements A) RWS/OCS shall clear a Message Available Flag in the outgoing status block if the corresponding Message Acknowledge Flag in the incoming status block has changed from the previous frame.

B) RWS/OCS shall write a message to be transmitted to one or more outgoing message blocks.

C) RWS/OCS shall write the Message Word Count in the outgoing status block in the location corresponding to the first message block of the message to be transmitted.

D) RWS/OCS shall set the Message Available Flag in the outgoing status block in the location corresponding to the first message block of the message to be transmitted.Retired

Message Transfer Requirements A) RWS/OCS shall read Message Word Count words starting from the corresponding message block when Message Available Flag is set in the incoming status block.

B) RWS/OCS shall toggle the corresponding Message Acknowledge Flag of the outgoing status block after reading the incoming message.

Timing and Synchronization Once RWS-OCS communications are initialized as per 3.2.1 above, the SMI is synchronized to a 50 ms cycle referred to as the local bus (LB) processing frame. The LB processing frame is triggered by the Camera Command Poll from SMC to RWS on the CB-EXT bus. The CB-EXT bus uses a 100 ms processing frame with two Camera Command Polls per frame. In the absence of the Camera Command Poll, RWS generates synthetic processing frames with an advisory such that they occur at 50 ms intervals.

A LB processing frame begins on the SMI when RWS issues a synchronization interrupt to OCS. The first synchronization interrupt issued by RWS marks the beginning of synchronous communication on the SMI. The synchronization interrupt is generated through the CEU Hardware Configuration Item as detailed in the CEU internal ICD, SPAR 830354. All subsequent communication is handled as per the message transfer protocol in 3.2.2 above, and the requirements of this section.

Figure 3.2.3-1 represents a typical 100 msec cycle of the SMC processing frame along with the message traffic on the SMI and local buses. The majority of SMI data will be passed through the RWS to the other interfaces.

SMI messages destined for the control and local buses are transferred by RWS into the earliest available bus slot. Likewise, messages received on these buses are transferred to the SMI as they are received. RWS provides a local bus frame count to OCS in order to provide a heartbeat and minimize latency between the SMI and the local buses. OCS returns an MSS frame count as its own heartbeat.

Whenever RWS accesses the SMI it will suspend processing in the OCS. The maximum time that OCS will be held during a local bus processing frame is limited by the requirements below. Current estimates for the transfer of a worst case set of message transfers indicate that 4 msec will be stolen from the OCS processing cycle. If a file transfer is also taking place, an extra 4 msec could be used for this transfer.

Figure 3.2.3-1 MESSAGE Synchronization Timing and Synchronization Requirements The following sub-paragraphs identify requirements on the OCS and RWS to maintain timing and synchronization.

A) RWS shall issue a synchronization interrupt to OCS every 50 +/- 0.5 ms.

B) RWS shall read data from the SMI between 37.5 ms and 43.70 ms measured from the last synchronization interrupt.

C) RWS shall write data to the SMI after 43.70 ms measured from the last synchronization interrupt and prior to issuing the next synchronization interrupt.

D) RWS shall use read and write access to the SMI for less than 8 ms per 50 ms processing frame.

E) OCS shall provide messages to RWS at the frequencies and times defined in Table 3.2.3.1-1 below.

F) RWS shall provide messages to OCS at the frequencies and times defined in Table 3.2.3.1-2 below, provided all components of the message were correctly received at the source.

G) RWS shall perform a message passing test every 50 ms processing frame at RWS-OCS message block 127. This test takes the form of a memory write/read test in the SMI and is considered a write operation for purposes of subparagraph c) above.Retired

3-9

TABLE 3.2.3.1-1 OCS TO RWS MESSAGES

( maximum 1 Hz )

NOTES:

(1) Messages may need to be passed on certain processing frames as stated in this column. This is in addition to the required transmission rate.

(2) Condition must be true before this message is used.

(3) In conformance with SPAR-SS-ICD-1148, SSRMS-related data are updated on Odd-numbered frames while SPDM-related data are updated on Even-numbered frames. Because of this, the actual rate of measured motor position data refresh is 10 Hz

(4) Message is sent by OCS to override the RMAD settings of the DCP Lights.

TABLE 3.2.3.1-2 RWS TO OCS MESSAGESRetired

SSP 41175-10, Tables 3.2.1 and 3.2.3.

(maximum 10 Hz)

Cyclic Data Enabled

Cyclic Data Enabled

NOTES: Retired

(1) Messages will not be transmitted if they are errors in their reception from another interface.

(2) No specific processing frames are required for RWS-OCS transfers. Only the transfer rate is necessary.

Every or Any => LB_Frame_Count = 0, 1, 2, ..., 19;

(3) Condition must be true before this message is used.

(4) RWS also uses this slot to provide OCS with BDU POST (BDU RT Download Status Message) during BDU initialization and Unit Download (see SPAR-SS-ICD-1957).

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RWS Services and Command/Response Protocol RWS manages all Input/Output operations and provides higher level services to OCS. OCS requests these services by sending appropriate commands through the SMI. The OCS command consists of a Command Identification (ID), and a sequence of Command Parameters whose format is dependent on the Command ID. RWS echoes back the Command ID, a Command Status, and a Command Response Parameter in the synchronization message. The Command ID is the identifier of the last command processed by the RWS. Upon start-up, this takes on a null value “0”. The Command Status can be Rejected, In Progress, Aborted, or Completed. The Command Response Parameter provides a reason or warning associated with the Command Status.

Only one command can be transmitted at a time. New commands will be rejected until the previous command has been completed, aborted or, rejected. The only command OCS can issue, before a command is completed, is an "Abort" command. When an ‘Abort’ command is issued for a currently executing command, the RWS will provide a command response for the command which is being aborted and a command response for the ‘Abort’ command.

Certain commands require the transfer of a large block of additional data which is performed through the SMI File Buffer. Not all data transferred by this protocol is stored on a disk as a file, but it is referred to as such for convenience. In the case of OCS-RWS transfers, the data is assumed to be present in the buffer when the command is issued. For RWS-OCS transfers, the data is made available in the buffer when a command Completed response is issued.

The basic requirements for fulfilling the command response protocol are listed below. The use of the word specified indicates an item which must be provided by OCS as part of the Command Parameters. Details are provided in Table 3.3.3-2 for the OCS-RWS commands, and in Table 3.3.4-1 for the command response.Retired

Services RWS shall provide the following services on command from OCS:

A) Configure the MSS and PDGF local buses for Remote Terminal (RT) or Bus Controller (BC) operation.

B) Initialize communication with specified subunits on a specified local bus. Any required power-up delays must have been observed by OCS before issuing this command. RWS will perform a data wrap test and, with the exception of the other RWS, retrieves a Fault Summary or BIT Summary Table for transmission to OCS.

C) Enable and disable cyclic data transfer with specified local bus subunits. The cyclic data is as defined by the MSS Local Bus ICD, SPAR-SS-ICD-1148, with the exception of Logged Data Upload.

D) Download specified files from SMC to specified local bus subunits.

E) Download specified files from SMC to the RWS-OCS file buffer.

F) Upload a specified amount of unit logged data from a specified subunit to a specified buffer within RWS.

G) Upload a specified amount of Event Driven Checkpoint Data from the OCS-RWS File Buffer to SMC.

H) Download specified amounts of Event Driven and Cyclic Checkpoint Data from the SMC to the RWS-OCS File Buffer.

I) Route Hand Controller Data to a specified subunit. The RWS will deroute hand controller data such that it is routed to no more than one unit at a time. This data includes the rate hold and vernier enable switches J) Route Hand Controller Trigger to a specified subunit. The RWS will deroute hand controller trigger such that it is routed to no more than one unit at a time.

K) Assign the default camera address a specified value. This instruction is issued via the SMC Camera Command Poll.

L) Bundle 11 specified subaddresses of local bus data for routing to the SMC Extended Data Dump. Note that OCS only provides routing information and the Extended Data Dump must be initiated via the SMC.

M) Abort a currently executing file, checkpoint data, or logged data transfer command.

N) Send joint angle softstop limits to both workstations.

O) Override the DCP Light settings specified in the RMAD.PIRN 0028 & 0031

P) Enable or disable the ability for the operator to remove power from MSS elements using the DCP Emergency stop switch.

Q) Switch between channels A and B of the specified local bus.Retired

General Response Requirements A) RWS shall issue a command response of Rejected with a reason if it cannot execute the most recently received command.

B) RWS shall issue a command response of In-Progress while executing a command.

C) RWS shall issue a command response of Aborted with a reason for in-progress commands which can no longer be successfully completed.

D) RWS shall issue a command response of Completed with any applicable warnings when it successfully completes an OCS command.

Failure Management This section describes the minimum failure management requirements on the SMI. The requirements listed below do not preclude additional detection and handling from being defined for each CSCI. Additional failure management should provoke a response which is detectable by the other CSCI by one of the methods listed below.

Failure Management Requirements

A) RWS shall cease synchronous communications with OCS if the MSS Frame Counter does not increment for two consecutive 50 ms frames. Note that this is a circular counter.

B) RWS shall cease synchronous communications with OCS if the Message Acknowledge Flag has not changed for two consecutive scheduled transmissions of that message.

C) RWS shall cease synchronous communication with OCS if the data read from the message passing test location is not equal to the data that was written for two consecutive 50 ms processing frames.

D) OCS shall cease synchronous communications with RWS if the Local Bus Frame Counter does not increment for two consecutive 50 ms frames. Note that this is a circular counter.

E) OCS shall cease synchronous communications with RWS if the Message Acknowledge Flag has not changed for two consecutive scheduled transmissions of that message.

Interface DesignRetired

This section describes the messages passed between OCS and RWS in detail.

Data Representation and Data Types This section addresses the format and representation of the data storage used by the OCS and RWS CSCI's.

Data Storage Implementation Bit Ordering The bit ordering used by the data elements represented in this ICD conforms to that of the intended target processors, the Intel 80x86 family parts (specifically 80386 Central Processing Unit (CPU) and 80387 Numerical Data Processor). Bit0 is always the least significant bit, with bits 7, 15, and 31 the most significant bits for bytes, words, and longwords, respectively.

32Bit Double Word A double word is four bytes occupying any four consecutive addresses. Data bytes are organized with byte 0 as the least significant byte, and byte 3 as the most significant byte. The address of a 32bit double word is the address of its least significant byte (byte 0).

16Bit Word A word is two bytes occupying any two consecutive addresses. Data bytes are organized with byte 0 as the least significant byte, and byte 1 as the most significant byte. The address of a 16bit word is the address of its least significant byte (byte 0).

Byte A byte is defined with bit 0 as the least significant bit, and bit 7 the most significant bit. Data bytes may be addressed at any address within available memory.

Numeric and Logical Data Representation The representation of numeric and logical data within the OCS and RWS CSCI's will conform to the definitions in Table 3.3.11.

TABLE 3.3.11 STANDARD NUMERIC DATA TYPESRetired

NOTE: Unsigned integers include enumerated types. An enumerated type is an unsigned integer whose numeric values have specific logical meanings.

Status Block Definition Table 3.3.2-1 describes the contents of the SMI Transfer Status Block for each side of the SMI.

TABLE 3.3.2-1 SMI TRANSFER STATUS BLOCK

Assignment Bit Assignment

1 => Message_Available.

1 => Message_Available.

1 => Message_Available.

1 => Message_Available.

1 => Message_Available.

1 => Message_Available.

1 => Message_Available.

1 => High.

1 => High.

1 => High.

1 => High.

1 => High.

1 => High.

1 => High.

Integer

Integer

Integer

Integer

OCS to RWS Message Interface The messages from OCS to RWS consist mostly of commands to RWS to provide message routing and file transfer services across the various buses and the SMI. Tables 3.3.3-1 to 3.3.3-9 contain the description of OCS to RWS messages.

Table 3.3.3-1 describes the OCS Sync Response Message which is updated every 50 msec. OCS will issue, at most, one of the commands listed in Tables 3.3.3-2 and 3.3.3-2A to 3.3.3-2E per 50 msec. cycle. Thus the messages contained in those tables will share the same SMI message slot.

The overlay data defined in Tables 3.3.3-3 to 3.3.3-9 is based upon data identified in SSP 50350, Robotics Workstation CCTV Screen Overlay Requirements, as being supplied by the OCS.

video graphics overlay messages

The following messages from OCS to RWS are used for the generation of the overlay data on both RWS workstations. Most of the data contained in these tables is for the “active manipulator”, the exception being the Point of Resolution (POR) data is available for all MSS arm manipulators, and “active end effector”. The determination of the active elements is via the parameters “Active_Manipulator” and “Active_Effector” contained in message 4, Table 3.3.3-6.

For the active effector data contained in the Graphics_Overlay_1 message the interpretation is different for Latching End Effector (LEE) type mechanism and ORU/Tool Changeout Mechanism (OTCM) mechanisms. The Active_Effector shall be used to determine the interpretation required. Note also that only one mechanism in the effector can be moving at any point in time and, therefore, only one mechanism position is reported in the message. For a LEE type mechanism the mechanism is reported as “In_Motion”. For an OTCM type mechanism, the VGS must use the Active_OTCM_Mechanism_Module. In order for the VGS to display all mechanism positions on the graphics overlay, the VGS must remember the last known position of each mechanism not currently moving.Retired

TABLE 3.3.3-1 SMI SYNC RESPONSE MESSAGE

Assignment Bit Assignment

Integer

1 => Ready

TABLE 3.3.3-2 OCS TO RWS COMMAND MESSAGE

Assignment Bit Assignment