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1、多路傳輸原理深入版本VAN系統(tǒng)的通訊協(xié)議-通訊協(xié)議定義了連接在VAN系統(tǒng)上的設(shè)備之間數(shù)據(jù)交換的標(biāo)準(zhǔn)和法則.-這些標(biāo)準(zhǔn)和法則定義了:數(shù)據(jù)通信包和信息結(jié)構(gòu)VAN系統(tǒng)數(shù)據(jù)優(yōu)先級(jí)的管理VAN系統(tǒng)的告知收到信息VAN系統(tǒng)的嵌入信息回應(yīng)(in-frameresponse)VAN系統(tǒng)的架構(gòu)VAN系統(tǒng)的部件VAN系統(tǒng)的運(yùn)行模式TheVAN(VehicleAreaNetwork)...TheVANBUSBUS由兩條橫截面積為0.6mm2相互絕緣的的銅導(dǎo)線組成用來(lái)傳輸信號(hào).這兩條導(dǎo)線定義為DATA和DATA-B;它們以相反相位傳輸信號(hào).兩條導(dǎo)線纏繞在一起已克服電磁信號(hào)的干擾VANBUS
2、…簡(jiǎn)單介紹VAN(VehicleAreaNetwork)...…VAN的數(shù)據(jù)通信包和結(jié)構(gòu)VAN通訊數(shù)據(jù)包…一條在多路傳輸網(wǎng)絡(luò)系統(tǒng)上傳遞的信息被叫作”數(shù)據(jù)包”…一個(gè)”數(shù)據(jù)包”由連續(xù)的電信號(hào)脈沖”字節(jié)”組成....”字節(jié)”的值是”1”或’0’“1”或“0”分別代表傳輸?shù)母叩碗娢籘heVAN(VehicleAreaNetwork)...Acommunication“packet”consistingof“1”and“0”bits...“1”“0”VAN通信“數(shù)據(jù)包”…VAN通信“數(shù)據(jù)包”由7部分組成…”信息結(jié)構(gòu)”TheVAN(VehicleAreaNetwork)...S
3、tartDataIdent.Com.CheckAck.EndStart開(kāi)始區(qū)-該信號(hào)告知網(wǎng)絡(luò)將馬上開(kāi)始數(shù)據(jù)的傳送TheIdentifier接收識(shí)別–數(shù)據(jù)包的接收設(shè)備名稱(地址)TheCommand命令–數(shù)據(jù)的屬性(命令/信息)VAN通信“數(shù)據(jù)包”…VAN通信“數(shù)據(jù)包”由7部分組成…”信息結(jié)構(gòu)”TheVAN(VehicleAreaNetwork)...StartDataIdent.Com.CheckAck.End信息數(shù)據(jù)Data–傳遞的命令或數(shù)據(jù)檢查Check-檢查信息的有效性接收確認(rèn)Acknowledgment–用以確認(rèn)傳遞的信息被接收方收到結(jié)束End-傳遞信息結(jié)束
4、,網(wǎng)絡(luò)回到初始狀態(tài)…TheVAN(VehicleAreaNetwork)...VAN網(wǎng)絡(luò)優(yōu)先權(quán)管理優(yōu)先權(quán)管理…VAN網(wǎng)絡(luò)允許信息以優(yōu)先權(quán)方式不間斷字節(jié)傳輸這個(gè)意思指當(dāng)多個(gè)信息數(shù)據(jù)同時(shí)要在網(wǎng)絡(luò)上傳播時(shí),擁有優(yōu)先級(jí)別高的信息數(shù)據(jù)將首先被允許在網(wǎng)絡(luò)上傳遞.VAN網(wǎng)絡(luò)將利用信息數(shù)據(jù)結(jié)構(gòu)中的Identifier來(lái)比較信息的優(yōu)先級(jí).TheVAN(VehicleAreaNetwork)...StartDataIdent.Com.CheckAck.End優(yōu)先權(quán)的管理…Identifier由12個(gè)字節(jié)組成.因此是12個(gè)1’或0’的組合我們定義0’比1’優(yōu)先,VAN系統(tǒng)對(duì)在Identi
5、fier中的字節(jié)進(jìn)行比較TheVAN(VehicleAreaNetwork)...StartDataIdent.Com.CheckAck.EndPriorityFrameManagement…Considerthefollowingexample;TheVAN(VehicleAreaNetwork)...EquipmentAEquipmentCEquipmentBStartData100100101111Com.CheckAck.EndEquipmentAStartData100011101101Com.CheckAck.EndEquipmentBStartData
6、100000101111Com.CheckAck.EndEquipmentCPriorityFrameManagement…Considerthefollowingexample;TheVAN(VehicleAreaNetwork)...EquipmentAEquipmentCEquipmentBStart100110101101EquipmentAStartEquipmentBStartEquipmentCStart1000OntheBUS100000111111100000101001失去優(yōu)先權(quán)1=滯后0=優(yōu)先PriorityFrameManagement…Co
7、nsiderthefollowingexample;TheVAN(VehicleAreaNetwork)...EquipmentAEquipmentCEquipmentBStartEquipmentBStartEquipmentCStart10000010OntheBUS100000111111100000101001失去優(yōu)先權(quán)1=滯后0=優(yōu)先PriorityFrameManagement…Considerthefollowingexample;TheVAN(VehicleAreaNetwork)...EquipmentAEquipmentCEquipmentB
