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Allocation of Service Types and Subtypes

Specification • The PUS provides a standard set of services that are targeted for communication between spacecraft and ground systems. Many of them may not be applicable to on-board communication between applications. However, nothing precludes their use in a JAS-based system. The PUS can be extended to add additional functionality to existing...

Communication Specification > JAS Packets > Packet Service Definitions > Allocation of Service Types and Subtypes

Buffer Fragmentation and Reassembly

Specification • In cases where a higher-level transmit application (or higher layer in a communications stack) must transmit a buffer of data that exceeds the JRDDP MTU size, the buffer must be fragmented into a series of JRDDP packets and then reassembled at the receive TEP before returning the buffer to the...

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Overall Functional Description > Buffer Fragmentation and Reassembly

CCSDS Telecommand and Telemetry Format Packet Standard

Specification • CCSDS Space Packet The CCSDS packet format consists of a packet primary header and packet data field. The header provides routing information for the packet and metadata that describes the packet. The data field is intended to be a user-defined field that can be customized for applications. Details of how...

Communication Specification > JAS Packets > CCSDS Telecommand and Telemetry Format Packet Standard

Channel Closing Process

Specification • The following sections present the interactions (in the form of UML Sequence Diagrams) between transmit and receive endpoints while closing a channel. Various error conditions are presented in order to show nominal, delayed, and worst case scenarios. The hexagonal icons represent the TEP states while the dashed green lines represent...

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Channel Operations > Channel Closing Process

Communication Specification

Specification • The Communication Specification provides details about network interfaces, communication services, and packet structures that were described in the Communication Profile. The figure below provides context of where the Communication Specification resides in the JAS standard. JAS Standard Hierarchy

Communication Specification

Data Types

Specification • The JAS standard does not require a specific length or encoding format for data types. Systems can define these based on what best suits their needs. Sizes, endianness, byte ordering, and bit ordering are typically driven based on the processing and memory architectures that are used. However, in order to...

Communication Specification > JAS Packets > JAS Packet Definition > Data Types

Device Access Service

Specification • The device access service, service type address 128, is used to request parameters from or command parameters to a specific device. The currently defined device access service parameters are shown in the following table. Service Type Service Subtype Subtype Description Cmd Tlm Service Parameters Data Types and Description 128 1...

Communication Specification > JAS Packets > Packet Service Definitions > JAS Specific Services Definitions > Device Access Service

ECSS Packet Utilization Standard

Specification • The figures below show a PUS telecommand and telemetry packet and their utilization within the CCSDS space packet specification. The PUS specification uses the user-definable fields of the CCSDS space packet in order to create a PUS packet. The specification defines a secondary header that provides additional metadata such as...

Communication Specification > JAS Packets > ECSS Packet Utilization Standard

JAS Command Packet

Specification • JAS Command Packet All fields are shown in bits. The variable length application data field must be an integral number of bytes for the packet error control calculation. Spare bits may be used for padding purposes at the end to ensure the packets are an even number of bytes in...

Communication Specification > JAS Packets > JAS Packet Definition > JAS Command Packet

JAS Efficient Exchange Protocol

Specification • The JAS Efficient Exchange Protocol (JEEP) uses the lower level SpaceWire data link layer to provide data delivery services to one or more higher level application processes. This document specifies the functional requirements for JEEP but does not specify the interfaces to the lower or higher level processes, which may...

Communication Specification > SpaceWire > Protocols > JAS Efficient Exchange Protocol

JAS Packet Definition

Specification • The JAS Packet is built upon CCSDS and PUS packet standards. Some modifications were made to enforce a layered architecture in order to promote reuse of applications. The following sections will highlight these differences in more detail.

Communication Specification > JAS Packets > JAS Packet Definition

JAS Packet Service

Specification • Error: unable to migrate element with tag="" The CCSDS/SOIS subnetwork packet service standard can be referenced if a generic packet service is needed. The JAS Packet Service is an implementation of the CCSDS/SOIS packet service, specifically tailored for the JAS packet. The following diagram shows how the JAS Packet Service...

Communication Specification > Subnetwork Services > JAS Packet Service

JAS Packets

Specification • Applications require a messaging format to allow them to communicate with each other. Legacy programs may already have a messaging format that they prefer to use. There is nothing that precludes any of the JAS communication protocols or data links from supporting these formats. The JAS Packet was developed for...

Communication Specification > JAS Packets

JAS Reliable Data Delivery Protocol

Specification • The JAS Reliable Data Delivery Protocol (JRDDP) uses the lower level SpaceWire data link layer to provide reliable packet delivery services to one or more higher level host application processes. This document specifies the functional requirements for JRDDP but does not specify the interfaces to the lower or higher level...

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol

JAS Specific Services Definitions

Specification • The JAS specific services will be based on the PUS service concept. Most PUS services were created for communication between onboard applications and ground systems. JAS adds additional services to support more onboard payload functions. [Placeholder: Additional development is needed to define the JAS specific services to support onboard payload...

Communication Specification > JAS Packets > Packet Service Definitions > JAS Specific Services Definitions

Results 1–25 of 61