SEP2.0通信协议研究
常见的物联网通信方式
常见的物联网通信方式展开全文一、前言早期的物联网是指两个或多个设备之间在近距离内的数据传输，解决物物相连，早期多采用有线方式，比如RS323、RS485，考虑设备的位置可随意移动的方便性(有根线太丑了)，后期更多的使用无线方式;随着时代进步和发展，社会逐步进入互联网，各类传感器采集数据越来越丰富，大数据应用随之而来，人们考虑把各类设备直接纳入互联网以方便数据采集、管理以及分析计算。
简而言之，物联网智能化已经不再局限于小型设备、小网络阶段，而是进入到完整的智能工业化领域，智能物联网化在大数据、云计算、虚拟现实上步入成熟，并纳入互联网整个大生态环境。
二、物联网的发展最早的物联网只是简单把两个设备用信号线连接在一起：后来使用了无线，也出现了简单的组网：在互联网时代，越来越多的传感器、设备接入互联网，互联网也不单是通过网线传输，引入了空中网、卫星网等，应用的领域也越来越广泛：三、常见的物联网通信方式笔者对常用的物联网通信方式进行归纳总结分为四大种类，见下图：1.有线传输设备之间用物理线直接相连，不是很方便。
主要有电线载波或载频、同轴线、开关量信号线、RS232串口、RS485、USB，这里只对常用的RS232串口、RS485、USB做介绍。
RS232串口：串行通信接口，全名是“数据终端设备(DTE)和数据通讯设备(DCE)之间串行二进制数据交换接口技术标准”，是电脑与其它设备传送信息的一种标准接口;该标准规定采用一个25个脚的DB25连接器，对连接器的每个引脚的信号内容加以规定，还对各种信号的电平加以规定;RS-232属单端信号传送，存在共地噪声和不能抑制共模干扰等问题，因此一般用于20m以内的通信，常用的串口线一般只有1~2米。
见图：RS-485总线：在要求通信距离为几十米到上千米时或者有多设备联网需求时，RS232无法满足，因此诞生了RS-485 串行总线标准。
RS-485采用平衡发送和差分接收，具有抑制共模干扰的能力,加上总线收发器具有高灵敏度，能检测低至200mV的电压，使得传输信号能在千米以外得到恢复，RS-485采用半双工工作方式，可以联网构成分布式系统，用于多点互连时非常方便，可以省掉许多信号线，允许最多并联32台驱动器和32台接收器。
ZigBee技术-图文
ZigBee技术-图文(6)安全：ZigBee提供了基于循环冗余校验(CRC)的数据包完整性检查功能,支持鉴权和认证，采用了AES-128的加密算法,各个应用可以灵活确定其安全属性。
3应用实例编辑功能。
该产品采用高性能的工业级ZigBee方案，提供SMT与DIP接口，可直接连接TTL接口设备，实现数据透明传输功能；低功耗设计，最低功耗小于1mA；提供6路I/O，可实现数字量输入输出、脉冲输出；其中有3路I/O还可实现模拟量采集、脉冲计数等功能。
该产品已广泛应用于物联网产业链中的M2M行业，如智能电网、智能交通、智能家居、金融、移动POS终端、供应链自动化、工业自动化、智能建筑、消防、公共安全、环境保护、气象、数字化医疗、遥感勘测、农业、林业、水务、煤矿、石化等领域。
zigbee组网模式应用设计1.采用高性能工业级ZigBee芯片2.低功耗设计，支持多级休眠和唤醒模式，最大限度降低功耗3.电源输入（DC2.0～3.6V）稳定可靠1.WDT看门狗设计，保证系统稳定2.提供TTL串行接口，SPI接口。
3.天线接口防雷保护（可选）标准易用1.采用2.0的SMA与DIP接口，特别适合于不同用户的应用需求。
2.提供TTL接口可直接连相同电压的TTL串口设备3.智能型数据模块，上电即可进入数据传输状态4.使用方便，灵活，多种工作模式选择5.方便的系统配置和维护接口6.支持串口软件升级和远程维护功能强大1.支持ZigBee无线短距离数据传输功能2.具备中继路由和终端设备功能3.支持点对点、点对多点、对等和Meh网络4.网络容量大：65000个节点5.节点类型灵活：中心节点、路由节点、终端节点可任意设置；6.发送模式灵活：广播发送或目标地址发送模式可选7.通信距离大ZigBee技术所采用的自组织网是怎么回事？举一个简单的例子就可以说明这个问题，当一队伞兵空降后，每人持有一个ZigBee网络模块终端，降落到地面后，只要他们彼此间在网络模块的通信范围内，通过彼此自动寻找，很快就可以形成一个互联互通的ZigBee网络。
Zigbee技术及其应用技术
Zig bee技术及其应用2013-09-21 21:37:38|分类：Zigbee技术|标签：ziqbee通信组网应川|字号订阅ZigBee是一种低速短距离传输的无线网络协议。
ZigBee协议从下到上分别为物理层(PHY)、媒体访问控制层(MAC)、传输层(TL)、网络层(NWK)、应用层(APL)等。
其中物理层和媒体访问控制层遵循IEEE 802.15.4标准的规定。
乙gBee网络主要特点是低功耗、低成本、低速率、支持大量节点、支持多种网络拓扑、低复朵度、快速、可靠、安全。
ZigBee网络中设备的可分为协调器(Coordinator)＞汇聚节点(Router)、传感器节点(EndDevice)等三种角色。
⑴与此同时，中国物联网校企联盟认为:zigbee作为一种短距离无线通信技术,山于其网络可以便捷的为用户提供无线数抓传输功能,因此在迦阳领域具有非常强的可应用性。
起源ZigBee译为”紫蜂”,它与蓝牙相类似。
是一种新兴的短距离无线通信技术，用于传感控制应用(Sensor and Control)o由IEEE 802.15工作组中提出,并由其TG4工作组制定规范。
2001 年8 月，ZigBee Alliance 成立。
2004年，ZigBee V1.0诞生。
它是Zigbee规范的第一个版本。
由于推出仓促，存在一些错误。
2006年，推出ZigBee 2006,比较完善。
2007年底，ZigBee PRO推出。
2009年3月，Zigbee RF4CE推出，具备更强的灵活性和远程控制能力。
2009年开始，Zigbee釆用了IETF的IPv6 6Lowpan标准作为新一代智能电网Smart Energy(SEP 2.0)的标准，致力于形成全球统一的易于与互联网集成的网络，实现端到端的网络通信。
随着美国及全球智能电网的建设，Zigbee将逐渐被IPv6/6Lowpan标准所取代。
ZigBee的底层技术基于IEEE 802.15.4,即其眇理屋和媒体访问控制层直接使用了IEEE 802.15.4的定义。
sep路由协议点评
sep路由协议点评摘要：1.引言2.SEP 路由协议简介3.SEP 路由协议的优势3.1 高效性3.2 灵活性3.3 安全性4.SEP 路由协议的不足4.1 兼容性问题4.2 复杂性5.总结正文：【引言】SEP 路由协议，全称“Scalable and Efficient Routing Protocol”，是一种可扩展且高效的路由协议。
近年来，随着互联网的快速发展，传统的路由协议已经无法满足日益增长的网络需求。
SEP 路由协议应运而生，以其高效性、灵活性和安全性受到业界的关注。
本文将对SEP 路由协议进行详细介绍和点评。
【SEP 路由协议简介】SEP 路由协议是一种基于路径向量路由协议的新型路由协议。
它采用了分布式哈希表（DHT）技术，以实现快速路由查找和数据包转发。
SEP 路由协议旨在解决传统路由协议在可扩展性、性能和安全性方面的问题，适用于大规模、复杂网络环境。
【SEP 路由协议的优势】【高效性】SEP 路由协议具有较高的路由查找效率。
它采用了DHT 技术，实现了基于内容的路由，避免了传统路由协议中的逐级查询，从而降低了路由计算的时间复杂度。
这对于大规模网络环境中的数据包转发具有显著优势。
【灵活性】SEP 路由协议支持灵活的路由策略。
管理员可以根据网络需求，自定义路由策略，如基于距离向量、链路状态等。
此外，SEP 路由协议还可以与多种网络协议（如TCP/IP、MPLS 等）兼容，满足不同场景下的应用需求。
【安全性】SEP 路由协议注重网络安全。
它采用了加密技术，保证了路由信息的机密性。
同时，SEP 路由协议支持动态路由，可以实时检测网络中的故障节点，并自动调整路由策略，提高了网络的容错能力。
【SEP 路由协议的不足】【兼容性问题】尽管SEP 路由协议兼容多种网络协议，但在实际应用中，仍然存在与其他协议的互通性问题。
这可能会限制SEP 路由协议在某些场景下的使用。
【复杂性】SEP 路由协议采用了较为复杂的技术，如DHT、加密等，使得协议的实现和部署相对复杂。
sep路由协议点评
sep路由协议点评SEP（路径选择演化协议）是一种用于无线网络中的路由协议，它的主要目标是提高网络的稳定性、增加网络的容量和减少网络的延迟。
SEP可以在多跳网络中动态地选择最佳的路由路径，并通过协商等方式来处理网络中的冲突和错误。
本文将对SEP的原理、优缺点以及应用场景进行详细的分析和评价。
首先，SEP采用了基于包转发表的方式来建立和维护网络中的路由路径。
每个节点都会维护一张转发表，用于记录可以到达其他节点的最佳路径。
通过定期的路由更新，节点可以根据收到的新路由信息更新转发表，并从中选择最优路径进行数据传输。
这种方式可以高效地选择合适的路由路径，从而提高网络的稳定性和容量。
其次，SEP采用了一种自适应的冲突解决机制，可以有效地解决网络中的冲突问题。
当有多个节点同时请求传输数据时，可能会导致冲突和数据丢失。
SEP通过引入协商机制，让节点在传输数据之前先进行协商，决定谁将先传输数据，从而避免冲突和数据丢失。
这种机制可以减少网络中的冲突，提高数据的可靠性和传输效率。
此外，SEP还具有较低的延迟特点。
它通过在网络中建立多条备用路径，并动态地选择最佳路径进行数据传输，从而减少了数据传输的延迟。
同时，SEP还可以及时处理网络中的错误和异常，通过路由更新和转发表的更新等方式来纠正错误路径，并迅速找到新的最佳路径进行数据传输，从而提高了网络的可用性和稳定性。
然而，SEP也存在一些不足之处。
首先，SEP的实施和维护成本较高。
由于SEP需要在每个节点上维护转发表，并进行定期的路由更新和协商，这些操作都需要消耗节点的计算和网络资源。
其次，SEP的扩展性有限。
当网络规模较大时，由于节点数量的增加，路由的选择和转发会变得更加复杂，可能会导致网络性能的下降和延迟的增加。
最后，SEP对网络拓扑的要求较高。
由于SEP需要在网络中建立多条备用路径，并动态地选择最佳路径，因此网络的拓扑结构需要足够复杂和灵活，以适应不同的数据传输需求。
CANSpecificationV2.0版本协议规范
BOSCHCAN SpecificationVersion 2.01991, Robert Bosch GmbH, Postfach 30 02 40, D-70442 StuttgartBOSCHROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart Sep. 1991 page 1RecitalThe acceptance and introduction of serial communication to more and more applications has led to requirements that the assignment of message identifiers to communication functions be standardized for certain applications. These applications can be realized with CAN more comfortably, if the address range that originally has been defined by 11 identifier bits is enlargedTherefore a second message format (’extended format’) is introduced that provides a larger address range defined by 29 bits. This will relieve the system designer from compromises with respect to defining well-structured naming schemes. Users of CAN who do not need the identifier range offered by the extended format, can rely on the conventional 11 bit identifier range (’standard format’) further on. In this case they can make use of the CAN implementations that are already available on the market, or of new controllers that implement both formats.In order to distinguish standard and extended format the first reserved bit of the CAN message format, as it is defined in CAN Specification 1.2, is used. This is done in such a way that the message format in CAN Specification 1.2 is equivalent to the standard format and therefore is still valid. Furthermore, the extended format has been defined so that messages in standard format and extended format can coexist within the same network.This CAN Specification consists of two parts, with•Part A describing the CAN message format as it is defined in CAN Specification 1.2;•Part B describing both standard and extended message formats.In order to be compatible with this CAN Specification 2.0 it is required that a CAN implementation be compatible with either Part A or Part B.NoteCAN implementations that are designed according to part A of this or according to previous CAN Specifications, and CAN implementations that are designed according to part B of this specification can communicate with each other as long as it is not made use of the extended format.CAN Specification 2.0PART A2 BASIC CONCEPTSCAN has the following properties•prioritization of messages•guarantee of latency times•configuration flexibility•multicast reception with time synchronization•system wide data consistency•multimaster•error detection and signalling•automatic retransmission of corrupted messages as soon as the bus is idle again •distinction between temporary errors and permanent failures of nodes and autonomous switching off of defect nodesLayered Structure of a CAN NodeApplication LayerObject Layer- Message Filtering- Message and Status HandlingTransfer Layer- Fault Confinement- Error Detection and Signalling- Message Validation- Acknowledgment- Arbitration- Message Framing- Transfer Rate and TimingPhysical Layer- Signal Level and Bit Representation- Transmission MediumROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart•The Physical Layer defines how signals are actually transmitted. Within this specification the physical layer is not defined so as to allow transmission medium and signal level implementations to be optimized for their application.•The Transfer Layer represents the kernel of the CAN protocol. It presents messages received to the object layer and accepts messages to be transmitted from the object layer. The transfer layer is responsible for bit timing andsynchronization, message framing, arbitration, acknowledgment, error detection and signalling, and fault confinement.•The Object Layer is concerned with message filtering as well as status and message handling.The scope of this specification is to define the transfer layer and the consequences of the CAN protocol on the surrounding layers.MessagesInformation on the bus is sent in fixed format messages of different but limited length (see section 3: Message Transfer). When the bus is free any connected unit may start to transmit a new message.Information RoutingIn CAN systems a CAN node does not make use of any information about the system configuration (e.g. station addresses). This has several important consequences.System Flexibility: Nodes can be added to the CAN network without requiring any change in the software or hardware of any node and application layer.Message Routing: The content of a message is named by an IDENTIFIER. The IDENTIFIER does not indicate the destination of the message, but describes the meaning of the data, so that all nodes in the network are able to decide by MESSAGE FILTERING whether the data is to be acted upon by them or not.Multicast: As a consequence of the concept of MESSAGE FILTERING any number of nodes can receive and simultaneously act upon the same message.Data Consistency: Within a CAN network it is guaranteed that a message is simultaneously accepted either by all nodes or by no node. Thus data consistency of a system is achieved by the concepts of multicast and by error handling.ROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartBit rateThe speed of CAN may be different in different systems. However, in a given system the bitrate is uniform and fixed.PrioritiesThe IDENTIFIER defines a static message priority during bus access.Remote Data RequestBy sending a REMOTE FRAME a node requiring data may request another node to send the corresponding DATA FRAME. The DATA FRAME and the corresponding REMOTE FRAME are named by the same IDENTIFIER.MultimasterWhen the bus is free any unit may start to transmit a message. The unit with the message of higher priority to be transmitted gains bus access.ArbitrationWhenever the bus is free, any unit may start to transmit a message. If 2 or more units start transmitting messages at the same time, the bus access conflict is resolved by bitwise arbitration using the IDENTIFIER. The mechanism of arbitration guarantees that neither information nor time is lost. If a DATA FRAME and a REMOTE FRAME with the same IDENTIFIER are initiated at the same time, the DATA FRAME prevails over the REMOTE FRAME. During arbitration every transmitter compares the level of the bit transmitted with the level that is monitored on the bus. If these levels are equal the unit may continue to send. When a ’recessive’ level is sent and a ’dominant’ level is monitored (see Bus Values), the unit has lost arbitration and must withdraw without sending one more bit.SafetyIn order to achieve the utmost safety of data transfer, powerful measures for error detection, signalling and self-checking are implemented in every CAN node.Error DetectionFor detecting errors the following measures have been taken:- Monitoring (transmitters compare the bit levels to be transmitted with the bit levels detected on the bus)- Cyclic Redundancy Check- Bit Stuffing- Message Frame CheckROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartPerformance of Error DetectionThe error detection mechanisms have the following properties:- all global errors are detected.- all local errors at transmitters are detected.- up to 5 randomly distributed errors in a message are detected.- burst errors of length less than 15 in a message are detected.- errors of any odd number in a message are detected.Total residual error probability for undetected corrupted messages: less thanmessage error rate * 4.7 * 10-11.Error Signalling and Recovery TimeCorrupted messages are flagged by any node detecting an error. Such messages are aborted and will be retransmitted automatically. The recovery time from detecting an error until the start of the next message is at most 29 bit times, if there is no further error.Fault ConfinementCAN nodes are able to distinguish short disturbances from permanent failures. Defective nodes are switched off.ConnectionsThe CAN serial communication link is a bus to which a number of units may be connected. This number has no theoretical limit. Practically the total number of units will be limited by delay times and/or electrical loads on the bus line.Single ChannelThe bus consists of a single channel that carries bits. From this data resynchronization information can be derived. The way in which this channel is implemented is not fixed in this specification. E.g. single wire (plus ground), two differential wires, optical fibres, etc.Bus valuesThe bus can have one of two complementary logical values: ’dominant’ or ’recessive’. During simultaneous transmission of ’dominant’ and ’recessive’ bits, the resulting bus value will be ’dominant’. For example, in case of a wired-AND implementation of the bus, the ’dominant’ level would be represented by a logical ’0’ and the ’recessive’ level by a logical ’1’. Physical states (e.g. electrical voltage, light) that represent the logical levels are not given in this specification.ROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartAcknowledgmentAll receivers check the consistency of the message being received and will acknowledge a consistent message and flag an inconsistent message.Sleep Mode / Wake-upTo reduce the system’s power consumption, a CAN-device may be set into sleep mode without any internal activity and with disconnected bus drivers. The sleep mode is finished with a wake-up by any bus activity or by internal conditions of the system. On wake-up, the internal activity is restarted, although the transfer layer will be waiting for the system’s oscillator to stabilize and it will then wait until it has synchronized itself to the bus activity (by checking for eleven consecutive ’recessive’ bits), before the bus drivers are set to "on-bus" again.In order to wake up other nodes of the system, which are in sleep-mode, a special wake-up message with the dedicated, lowest possible IDENTIFIER (rrr rrrd rrrr; r =’recessive’ d = ’dominant’) may be used.ROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart3 MESSAGE TRANSFER3.1 Frame TypesMessage transfer is manifested and controlled by four different frame types:A DATA FRAME carries data from a transmitter to the receivers.A REMOTE FRAME is transmitted by a bus unit to request the transmission of the DATA FRAME with the same IDENTIFIER.An ERROR FRAME is transmitted by any unit on detecting a bus error.An OVERLOAD FRAME is used to provide for an extra delay between the preceding and the succeeding DATA or REMOTE FRAMEs.DATA FRAMEs and REMOTE FRAMEs are separated from preceding frames by an INTERFRAME SPACE.3.1.1 DATA FRAMEA DATA FRAME is composed of seven different bit fields:START OF FRAME, ARBITRATION FIELD, CONTROL FIELD, DATA FIELD, CRC FIELD, ACK FIELD, END OF FRAME. The DATA FIELD can be of length zero.Interframe Space InterframeSpaceStart of FrameArbitration FieldControl FieldData FieldCRC FieldACK FieldEnd of Frameor Overload FrameDATA FRAMEROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartSTART OF FRAMEmarks the beginning of DATA FRAMES and REMOTE FRAMEs. It consists of a single ’dominant’ bit.A station is only allowed to start transmission when the bus is idle (see BUS IDLE). All stations have to synchronize to the leading edge caused by START OF FRAME (see ’HARD SYNCHRONIZATION’) of the station starting transmission first.ARBITRATION FIELDThe ARBITRATION FIELD consists of the IDENTIFIER and the RTR-BIT.IDENTIFIERThe IDENTIFIER’s length is 11 bits. These bits are transmitted in the order from ID-10to ID-0. The least significant bit is ID-0. The 7 most significant bits (ID-10 - ID-4) must not be all ’recessive’.RTR BITRemote Transmission Request BITIn DATA FRAMEs the RTR BIT has to be ’dominant’. Within a REMOTE FRAME the RTR BIT has to be ’recessive’.CONTROL FIELDThe CONTROL FIELD consists of six bits. It includes the DATA LENGTH CODE and two bits reserved for future expansion. The reserved bits have to be sent ’dominant’.Receivers accept ’dominant’ and ’recessive’ bits in all combinations.DATA LENGTH CODEThe number of bytes in the DATA FIELD is indicated by the DATA LENGTH CODE.This DATA LENGTH CODE is 4 bits wide and is transmitted within the CONTROL FIELD.Interframe Space Start of FrameIdentifierRTR BitControl FieldARBITRATION FIELDROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartCoding of the number of data bytes by the DATA LENGTH CODE abbreviations:d ’dominant’r ’recessive’DATA FRAME: admissible numbers of data bytes: {0,1,....,7,8}.Other values may not be used.r1r0DLC3DLC2DLC1DLC0or CRC FieldArbitration FieldData Field CONTROL FIELDData Length Codereserved bits012345678d d d d d d d d rd d d d r r r r dd d r r d d r r dd r d r d r d r dDLC3DLC2DLC1DLC0Number of DataBytesData Length CodeROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartDATA FIELDThe DATA FIELD consists of the data to be transferred within a DATA FRAME. It can contain from 0 to 8 bytes, which each contain 8 bits which are transferred MSB first.CRC FIELDcontains the CRC SEQUENCE followed by a CRC DELIMITER.CRC SEQUENCEThe frame check sequence is derived from a cyclic redundancy code best suited for frames with bit counts less than 127 bits (BCH Code).In order to carry out the CRC calculation the polynomial to be divided is defined as the polynomial, the coefficients of which are given by the destuffed bit stream consisting of START OF FRAME, ARBITRATION FIELD, CONTROL FIELD, DATA FIELD (if present) and, for the 15 lowest coefficients, by 0. This polynomial is divided (the coefficients are calculated modulo-2) by the generator-polynomial:X 15 + X 14 + X 10 + X 8 + X 7 + X 4 + X 3 + 1.The remainder of this polynomial division is the CRC SEQUENCE transmitted over the bus. In order to implement this function, a 15 bit shift register CRC_RG(14:0) can be used. If NXTBIT denotes the next bit of the bit stream, given by the destuffed bit sequence from START OF FRAME until the end of the DATA FIELD, the CRC SEQUENCE is calculated as follows:CRC_RG = 0;// initialize shift register REPEATCRCNXT = NXTBIT EXOR CRC_RG(14);CRC_RG(14:1) = CRC_RG(13:0);// shift left by CRC_RG(0) = 0;// 1 positionData or Control FieldCRC SequenceCRC DelimiterAck FieldCRC FIELDROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartIF CRCNXT THENCRC_RG(14:0) = CRC_RG(14:0) EXOR (4599hex);ENDIFUNTIL (CRC SEQUENCE starts or there is an ERROR condition)After the transmission / reception of the last bit of the DATA FIELD, CRC_RG contains the CRC sequence.CRC DELIMITERThe CRC SEQUENCE is followed by the CRC DELIMITER which consists of a single ’recessive’ bit.ACK FIELDThe ACK FIELD is two bits long and contains the ACK SLOT and the ACK DELIMITER.In the ACK FIELD the transmitting station sends two ’recessive’ bits.A RECEIVER which has received a valid message correctly, reports this to the TRANSMITTER by sending a ’dominant’ bit during the ACK SLOT (it sends ’ACK’).ACK SLOTAll stations having received the matching CRC SEQUENCE report this within the ACK SLOT by superscribing the ’recessive’ bit of the TRANSMITTER by a ’dominant’ bit.ACK DELIMITERThe ACK DELIMITER is the second bit of the ACK FIELD and has to be a ’recessive’bit. As a consequence, the ACK SLOT is surrounded by two ’recessive’ bits (CRC DELIMITER, ACK DELIMITER).END OF FRAMEEach DATA FRAME and REMOTE FRAME is delimited by a flag sequence consisting of seven ’recessive’ bits.CRC FieldACK SlotACK DelimiterEnd of FrameACK FIELDROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart3.1.2 REMOTE FRAMEA station acting as a RECEIVER for certain data can initiate the transmission of the respective data by its source node by sending a REMOTE FRAME.A REMOTE FRAME is composed of six different bit fields:START OF FRAME, ARBITRATION FIELD, CONTROL FIELD, CRC FIELD, ACK FIELD, END OF FRAME.Contrary to DATA FRAMEs, the RTR bit of REMOTE FRAMEs is ’recessive’. There is no DATA FIELD, independent of the values of the DATA LENGTH CODE which may be signed any value within the admissible range 0...8. The value is the DATA LENGTH CODE of the corresponding DATA FRAME.The polarity of the RTR bit indicates whether a transmitted frame is a DATA FRAME (RTR bit ’dominant’) or a REMOTE FRAME (RTR bit ’recessive’).Inter SpaceInter Space Start of FrameArbitration FieldControl FieldCRC FieldACK FieldEnd of Frameor Overload FrameREMOTE FRAMEFrame FrameROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart3.1.3 ERROR FRAMEThe ERROR FRAME consists of two different fields. The first field is given by the superposition of ERROR FLAGs contributed from different stations. The following second field is the ERROR DELIMITER.In order to terminate an ERROR FRAME correctly, an ’error passive’ node may need the bus to be ’bus idle’ for at least 3 bit times (if there is a local error at an ’error passive’ receiver). Therefore the bus should not be loaded to 100%.ERROR FLAGThere are 2 forms of an ERROR FLAG: an ACTIVE ERROR FLAG and a PASSIVE ERROR FLAG.1.The ACTIVE ERROR FLAG consists of six consecutive ’dominant’ bits.2.The PASSIVE ERROR FLAG consists of six consecutive ’recessive’ bits unless it is overwritten by ’dominant’ bits from other nodes.An ’error active’ station detecting an error condition signals this by transmission of an ACTIVE ERROR FLAG. The ERROR FLAG’s form violates the law of bit stuffing (see CODING) applied to all fields from START OF FRAME to CRC DELIMITER or destroys the fixed form ACK FIELD or END OF FRAME field. As a consequence, all other stations detect an error condition and on their part start transmission of an ERROR FLAG. So the sequence of ’dominant’ bits which actually can be monitored on the bus results from a superposition of different ERROR FLAGs transmitted by individual stations. The total length of this sequence varies between a minimum of six and a maximum of twelve bits.An ’error passive’ station detecting an error condition tries to signal this by transmission of a PASSIVE ERROR FLAG. The ’error passive’ station waits for six consecutive bitsData FrameError FlagError DelimiterInterframe Space or ERROR FRAMEOverload Framesuperposition of Error FlagsROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgartof equal polarity, beginning at the start of the PASSIVE ERROR FLAG. The PASSIVE ERROR FLAG is complete when these 6 equal bits have been detected.ERROR DELIMITERThe ERROR DELIMITER consists of eight ’recessive’ bits.After transmission of an ERROR FLAG each station sends ’recessive’ bits and monitors the bus until it detects a ’recessive’ bit. Afterwards it starts transmitting seven more ’recessive’ bits.3.1.4 OVERLOAD FRAMEThe OVERLOAD FRAME contains the two bit fields OVERLOAD FLAG and OVERLOAD DELIMITER.There are two kinds of OVERLOAD conditions, which both lead to the transmission of an OVERLOAD FLAG:1.The internal conditions of a receiver, which requires a delay of the next DATA FRAME or REMOTE FRAME.2.Detection of a ’dominant’ bit during INTERMISSION.The start of an OVERLOAD FRAME due to OVERLOAD condition 1 is only allowed to be started at the first bit time of an expected INTERMISSION, whereas OVERLOAD FRAMEs due to OVERLOAD condition 2 start one bit after detecting the ’dominant’ bit.At most two OVERLOAD FRAMEs may be generated to delay the next DATA or REMOTE FRAME.End of Frame or Overload Overload DelimiterInter Space or OVERLOAD FRAMEOverload Framesuperposition of Overload FlagsFlagFrame Error Delimiter or Overload DelimiterOVERLOAD FLAGconsists of six ’dominant’ bits. The overall form corresponds to that of the ACTIVE ERROR FLAG.The OVERLOAD FLAG’s form destroys the fixed form of the INTERMISSION field. As a consequence, all other stations also detect an OVERLOAD condition and on their part start transmission of an OVERLOAD FLAG. (In case that there is a ’dominant’ bit detected during the 3rd bit of INTERMISSION locally at some node, the other nodes will not interpret the OVERLOAD FLAG correctly, but interpret the first of these six ’dominant’ bits as START OF FRAME. The sixth ’dominant’ bit violates the rule of bit stuffing causing an error condition).OVERLOAD DELIMITERconsists of eight ’recessive’ bits.The OVERLOAD DELIMITER is of the same form as the ERROR DELIMITER. After transmission of an OVERLOAD FLAG the station monitors the bus until it detects a transition from a ’dominant’ to a ’recessive’ bit. At this point of time every bus station has finished sending its OVERLOAD FLAG and all stations start transmission of seven more ’recessive’ bits in coincidence.3.1.5 INTERFRAME SPACINGDATA FRAMEs and REMOTE FRAMEs are separated from preceding frames whatever type they are (DATA FRAME, REMOTE FRAME, ERROR FRAME, OVERLOAD FRAME) by a bit field called INTERFRAME SPACE. In contrast, OVERLOAD FRAMEs and ERROR FRAMEs are not preceded by an INTERFRAME SPACE and multiple OVERLOAD FRAMEs are not separated by an INTERFRAME SPACE.INTERFRAME SPACEcontains the bit fields INTERMISSION and BUS IDLE and, for ’error passive’ stations, which have been TRANSMITTER of the previous message, SUSPEND TRANSMISSION.ROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartBOSCHROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 StuttgartSep. 1991Part A - page 19For stations which are not ’error passive’ or have been RECEIVER of the previous message:For ’error passive’ stations which have been TRANSMITTER of the previous message:INTERMISSIONconsists of three ’recessive’ bits.During INTERMISSION no station is allowed to start transmission of a DATA FRAME or REMOTE FRAME. The only action to be taken is signalling an OVERLOAD condition.BUS IDLEThe period of BUS IDLE may be of arbitrary length. The bus is recognized to be free and any station having something to transmit can access the bus. A message, which is pending for transmission during the transmission of another message, is started in the first bit following INTERMISSION.The detection of a ’dominant’ bit on the bus is interpreted as a START OF FRAME.SUSPEND TRANSMISSIONAfter an ’error passive’ station has transmitted a message, it sends eight ’recessive’bits following INTERMISSION, before starting to transmit a further message or recognizing the bus to be idle. If meanwhile a transmission (caused by another station)starts, the station will become receiver of this message.FrameBus IdleINTERFRAME SPACEIntermission FrameFrameBus IdleINTERFRAME SPACEIntermissionFrameSuspend TransmissionInterframe SpaceBOSCHROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart Sep. 1991Part A - page 20 3.2 Definition of TRANSMITTER / RECEIVERTRANSMITTERA unit originating a message is called “TRANSMITTER” of that message. The unit stays TRANSMITTER until the bus is idle or the unit loses ARBITRATION.RECEIVERA unit is called “RECEIVER” of a message, if it is not TRANSMITTER of that message and the bus is not idle.Transmitter / ReceiverBOSCHROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart Sep. 1991Part A - page 21 4 MESSAGE VALIDATIONThe point of time at which a message is taken to be valid, is different for the transmitter and the receivers of the message.Transmitter:The message is valid for the transmitter, if there is no error until the end of END OF FRAME. If a message is corrupted, retransmission will follow automatically and according to prioritization. In order to be able to compete for bus access with other messages, retransmission has to start as soon as the bus is idle.Receivers:The message is valid for the receivers, if there is no error until the last but one bit of END OF FRAME.Message Validation5 CODINGBIT STREAM CODINGThe frame segments START OF FRAME, ARBITRATION FIELD, CONTROL FIELD, DATA FIELD and CRC SEQUENCE are coded by the method of bit stuffing. Whenever a transmitter detects five consecutive bits of identical value in the bit stream to be transmitted it automatically inserts a complementary bit in the actual transmitted bit stream.The remaining bit fields of the DATA FRAME or REMOTE FRAME (CRC DELIMITER, ACK FIELD, and END OF FRAME) are of fixed form and not stuffed. The ERROR FRAME and the OVERLOAD FRAME are of fixed form as well and not coded by the method of bit stuffing.The bit stream in a message is coded according to the Non-Return-to-Zero (NRZ) method. This means that during the total bit time the generated bit level is either ’dominant’ or ’recessive’.ROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart6 ERROR HANDLING6.1 Error DetectionThere are 5 different error types (which are not mutually exclusive):•BIT ERRORA unit that is sending a bit on the bus also monitors the bus. A BIT ERROR has tobe detected at that bit time, when the bit value that is monitored is different from the bit value that is sent. An exception is the sending of a ’recessive’ bit during thestuffed bit stream of the ARBITRATION FIELD or during the ACK SLOT. Then no BIT ERROR occurs when a ’dominant’ bit is monitored. A TRANSMITTER sendinga PASSIVE ERROR FLAG and detecting a ’dominant’ bit does not interpret this asa BIT ERROR.•STUFF ERRORA STUFF ERROR has to be detected at the bit time of the 6th consecutive equal bitlevel in a message field that should be coded by the method of bit stuffing.•CRC ERRORThe CRC sequence consists of the result of the CRC calculation by the transmitter.The receivers calculate the CRC in the same way as the transmitter. A CRCERROR has to be detected, if the calculated result is not the same as that received in the CRC sequence.•FORM ERRORA FORM ERROR has to be detected when a fixed-form bit field contains one ormore illegal bits.•ACKNOWLEDGMENT ERRORAn ACKNOWLEDGMENT ERROR has to be detected by a transmitter whenever it does not monitor a ’dominant’ bit during the ACK SLOT.6.2 Error SignallingA station detecting an error condition signals this by transmitting an ERROR FLAG. For an ’error active’ node it is an ACTIVE ERROR FLAG, for an ’error passive’ node it is a PASSIVE ERROR FLAG. Whenever a BIT ERROR, a STUFF ERROR, a FORM ERROR or an ACKNOWLEDGMENT ERROR is detected by any station, transmission of an ERROR FLAG is started at the respective station at the next bit.Whenever a CRC ERROR is detected, transmission of an ERROR FLAG starts at the bit following the ACK DELIMITER, unless an ERROR FLAG for another condition has already been started.ROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart7 FAULT CONFINEMENTWith respect to fault confinement a unit may be in one of three states:•’error active’•’error passive’•’bus off’An ’error active’ unit can normally take part in bus communication and sends an ACTIVE ERROR FLAG when an error has been detected.An ’error passive’ unit must not send an ACTIVE ERROR FLAG. It takes part in bus communication but when an error has been detected only a PASSIVE ERROR FLAG is sent. Also after a transmission, an ’error passive’ unit will wait before initiating a further transmission. (See SUSPEND TRANSMISSION)A ’bus off’ unit is not allowed to have any influence on the bus. (E.g. output drivers switched off.)For fault confinement two counts are implemented in every bus unit:1) TRANSMIT ERROR COUNT2) RECEIVE ERROR COUNTThese counts are modified according to the following rules:(note that more than one rule may apply during a given message transfer)1.When a RECEIVER detects an error, the RECEIVE ERROR COUNT will beincreased by 1, except when the detected error was a BIT ERROR during the sending of an ACTIVE ERROR FLAG or an OVERLOAD FLAG.2.When a RECEIVER detects a ’dominant’ bit as the first bit after sending an ERRORFLAG the RECEIVE ERROR COUNT will be increased by 8.3.When a TRANSMITTER sends an ERROR FLAG the TRANSMIT ERROR COUNTis increased by 8.Exception 1:If the TRANSMITTER is ’error passive’ and detects an ACKNOWLEDGMENTROBERT BOSCH GmbH, Postfach 30 02 40, D-70442 Stuttgart。
6LoWPAN 的主要功能_无线传感网络_[共2页]
![6LoWPAN 的主要功能_无线传感网络_[共2页]](https://img.taocdn.com/s3/m/aa323dc552d380eb63946d2a.png)
第2章短距离无线通信技术与标准39 人员开发IP选择协议是为了利用以太网等“现代”技术。
6LoWPAN的出现使这些老协议把它们的IP选择扩展到新的链路（如802.15.4）。
因此，自然而然地可与专为802.15.4设计的新协议（如ZigBee、ISA100.11a等）互操作。
受益于此，各类低功率无线设备能够加入IP家庭中，与Wi-Fi、以太网以及其他类型的网络设备“称兄道弟”。
随着IPv4地址的耗尽，IPv6是大势所趋。
物联网技术的发展，将进一步推动IPv6的部署与应用。
IETF 6LoWPAN技术具有无线低功耗、自组织网络的特点，将是未来无线传感网络的重要技术之一。
在ZigBee新一代智能电网标准中，SEP2.0（Smart Energy Protocol 2.0）协议就已经采用6LoWPAN技术。
随着6LoWPAN的不断发展和完善，6LoWPAN将成为事实标准，全面替代ZigBee标准，未来ZigBee应用系统将无需网关而直接连入IP网，大大降低了ZigBee的部署难度，提高了ZigBee的易用性。
2.2.2 6LoWPAN的体系结构6LoWPAN技术是一种在IEEE 802.15.4标准基础上传输IPv6数据包的网络体系，可用于构建无线传感网络。
6LoWPAN规定其物理层和MAC层采用IEEE 802.15.4标准，上层采用TCP/IPv6协议栈，中间有个适配层完成IPv6与LoWPAN（Low Power Wireless Personal Area Networks）的网络衔接，适配层是IPv6网络和IEEE 802.15.4 MAC层间的一个中间层，其向上提供IPv6对IEEE 802.15.4媒介访问支持，向下则控制LoWPAN网络构建、拓扑及MAC层路由。
其与TCP/IP的协议栈参考模型对比如图2-6所示。
图2-6 6LoWPAN体系架构6LoWPAN协议栈参考模型与TCP/IP的参考模型大致相似，区别在于6LoWPAN底层使用的IEEE 802.15.4标准，而且因低速无线个域网的特性，在6LoWPAN的传输层没有使用TCP协议。
sep路由协议点评
sep路由协议点评
（最新版）
目录
1.介绍 SEP 路由协议
2.SEP 路由协议的优点
3.SEP 路由协议的缺点
4.SEP 路由协议的应用场景
5.总结
正文
SEP（Scalable End-to-End Protocol）是一种用于互联网的路由协议，其设计初衷是为了解决现有路由协议的可扩展性和可靠性问题。
SEP 路由协议采用了一种全新的路由算法，可以有效地提高网络的性能和稳定性，因此在近年来受到了广泛关注。
首先，我们来看看 SEP 路由协议的优点。
SEP 路由协议的可扩展性非常好，可以支持大量的并发连接，而不会出现性能下降的情况。
这是因为 SEP 路由协议采用了一种基于事件驱动的建筑机制，使得路由器可以在接收到数据包后快速地进行处理。
此外，SEP 路由协议还具有很好的可靠性，可以有效地避免路由环的产生，从而提高了网络的稳定性。
然而，SEP 路由协议也存在一些缺点。
首先，SEP 路由协议的部署成本较高，需要对现有的网络设备进行升级，以支持 SEP 路由协议。
其次，SEP 路由协议的配置和管理比较复杂，需要网络管理员具备较高的技术水平。
总的来说，SEP 路由协议是一种具有很高可扩展性和可靠性的路由协议，适用于大型互联网企业和数据中心等场景。
第1页共1页。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
SEP2.0通信协议研究
【摘要】由Wi-Fi、ZigBee、HomePlug与HomeGrid 等成员推动的Smart Energy Protocol 2.0（SEP2.0）标准能够通过智能设备中的应用程序，实现家庭内部的能源管理，提高能源利用效率，节能降耗，有效支撑智能电网，论文对SEP2.0的发展及主要内容进行了研究。
【关键词】智能用电信息模型SEP2.0
一、引言
近几十年来，能源短缺和能源消费引起的环境污染问题已经发展为世界性的难题，世界各国在寻求能量转型道路时都把提高能源利用效率，节能降耗列为能源可持续发展的关键环节[1]。
SEP2.0之前，Zigbee联盟推行了基于Zigbee协议的SE1.X协议，但因协议的封闭性与局限性并且得到广泛应用[2]。
SEP2.0能够提供用户与智能电网的连接外，SEP2.0还能通过网络市场上的应用程序，实现家庭内部的能源管理。
更重要的是，SEP2.0的程序开发不仅与电网有关，更是可以联合厂商与服务商，为用户提供更好的体验。
论文对SEP2.0的发展及主要内容进行了研究。
二、主要特征
如图1所示，SEP2.0的底层虽然建议采用802.15.4或802.11无线协议，但是事实上对于任何能够采用HTTP协议的接入方式都是支持的（包括有线的），SEP2.0着重定义最高层的CIM模型与EXI（Efficient XML Interchange）部分，对于其他支撑协议采用现有的、适用面广、普及度高的协议实现，如：HTTP、DNS-SD、TLS等[3]。
SEP2.0着重于其资源模型的定义，对于传输发现等网络通信内容采用主流成熟的协议/架构来实现，其总体框架采用RESTful HTTP实现、服务发现采用类DNS方式实现、安全传输采用TLS实现。
这些支撑内容处于模型之下、网络之上。
三、信息模型
SEP 2.0的资源表示与建立是通过UML语言实现的，是CIM的一种扩展，将模型分为三大类：Support Resources（辅助资源）、Common Resources（通用资源）、Smart Energy Resouces（SE资源）。
辅助资源用于支撑设备通用的信息处理与交换，能力较为简单，建议每个设备都具备的辅助资源提供的能力，包括：设备能力、设备接口、通信接口、资源预设、订阅通知算法、响应算法。
通用资源是与具体应用无关的，可以用于支撑智能用电资源的功能集，包括：时间、设备信息、电源状态、网络状态、日志、配置、文件下载。
SE资源用于实现智能用电的特定应用场景，包括：DRLC、计量、电价、文本通知、费用、预付费、预订能量、DER及智能用电的通用资源。
四、结论
SEP2.0通过UML语言建立了一组完善的信息模型，采用现有成熟的协议来实现信息交互，创建了一个标准的、可互操作的协议，用于智能电网与用户设备的连接。
通过TCP/IP协议承载业务，与物理层协议完全分离，提供用户与智能电网的连接，实现家庭内部的能源管理，能够为我国用户领域的节能减排通信协议提供一个良好的参考。
参考文献
[1] 黄飞. 能源消费与国民经济发展的灰色关联分析[J]. 热能动力工程，2001，16（1）：89-90
[2] Zigbee Alliance. Zigbee Smart Energy Profile Specifications [S]
[3] Zigbee Alliance. SEP 2.0 Application Specification 0.9 Document [S]。