BACnet通讯分析

1、BACnet通讯1、概述.系统实现基于 BACnet/IP （又称B/IP ）网络进行通讯。BACnet虚拟链路层（BVLL ）提 供了 BACnet网络层和某指定的通讯子系统的接口，本文指定了BACnet虚拟链路控制（BVLC ）要求支持的定向和广播信息。 本实现关于BACnet协议定义主要可分为三层： B/IP网络虚拟层，BACnet网络层和BACnet应用层。B/IP提供了 TCP/IP 一样的通讯结构，采用 UDP的通讯方式。本文接下来将对此三层结构进行详细的讲解。其文本协议的大致格式如下:BAC net/IPBACnet网络层BACnet应用层BVLC TypeBVLC Fun ct

2、ionLen gthNPDUAPDUNPDU : BACnet网络层数据结构，下文进行详细的讲解APDU : BACnet应用层数据结构，下文进行详细的讲解2、BACnet/IP.BVLC Type :0 x81，代表 BACnet/IP 网络BVLC Function :指定报文的类型，何种作用；本应用使用的报文类型分为两种：0A :点对点通讯0B :广播通信Length :指定报文的长度，包括BVLC Type、BVLC Function以及本身在内NPDU :根据不同情况，报文长短不同，见下文的解析。APDU :根据NPDU不同以及不同的请求，报文不同，见下文的解析。3、BACnet N

3、PDU 结构.版本信息1 ByteVersio n控制字1 ByteCo ntrol目标网络号2 BytesDNET目标网络长度1 ByteDLEN目标地址可变长度DADR原网络号2 BytesSNET原网络长度1 ByteSLEN原地址可变SNET路由数目1 ByteHop Cou nt消息类型1 ByteMessage Type卖方ID2 BytesVendor ID应用层信息可变APDU版本信息 ：默认0 x01控制字：BIT7 : 1表示Message Type存在，为0时Message Type不存在con firmed-request-PDU0 BAC net-C on firme

4、d-Request-PDU,BIT6 :保留，为0BIT5 : 1表示DNET DLEN Hop Count 存在，当 DLEN为0时表明广播网络 DADR 不存在；0 表示 DNET DLEN DADR Hop Count不存在BIT4 :保留，为0BIT3 : 1表示SNET SLEN存在，当 SLEN为0时表明无效 SADR不存在； 0 表示 SNET SLEN SADR Hop Count 不存在BIT2 : 1表示为一个需确认的请求数据单兀，一复杂ACK数据单兀或一网络层信息非reply的；0表示除去上述情形的数据单兀BIT1、0:网络优先级11 = Life Safety mess

5、age10 = Critical Equipment message01 = Urgent message00 = Normal message目标网络号：FFFF的时候表示广播目标长度：目标地址：表示DADR的长度 目标网络MAC地址原网络号：同目标网络号原网络长度：表示 SADR的长度原地址：原网络的MAC地址路由数目：数据需要经过的路由个数，当不存在DNET的时候，需设置为 FF消息类型：X00: Who-ls-Router-To-NetworkX01: I-Am-Router-To-NetworkX02: I-Could-Be-Router-To-NetworkX03: Reject-

6、Message-To-NetworkX04: Router-Busy-To-NetworkX05: Router-Available-To-NetworkX06: In itialize-Rout in g-TableX07: Initialize-Routing-Table-AckX08: Establish-Co nn ectio n-To-NetworkX09: Disco nn ect-Co nn ectio n-To-NetworkX0A to X7F: Reserved for use by ASHRAEX80 to XFF: Available for ven dor propr

7、ietary messages卖方ID :当控制字的 BIT7为1并且消息类型为 X80 to XFF:的时候，才会存在 本次开发没有用到，不再解释本次应用中控制字只用到0 x20和0 x04两种，前者为广播查询设备， 后者微点对对取设备数据或属性。4、BACnet APDU结构：（应用层协议数据单元）BACnet网络层数据主要分为一下几种:BAC netPDU := CHOICEuncon firmed-request-PDU simpleACK-PDU complexACK-PDU segme ntAck-PDU error-PDUreject-PDU abort-PDUreservedm

8、ax-segme nts-acceptedmax-APDU-le ngth-acceptedin vokeIDseque nce-nu mber proposed-w in dow-size service-choice service-requestPDU TypeSEG1 BACn et- Uncon firmed-Request-PDU,2 BAC net-SimpleACK-PDU,3 BAC net-ComplexACK-PDU,4 BAC net-Segme ntACK-PDU,5 BAC net-Error-PDU, BAC net-Reject-PDU,7 BAC net-Ab

9、ort-PDU对于本次应用，主要用到了BAC net-Co nfirmed-Request-PDU （需确认的请求协议数据单元）BACn et- Uncon firmed-Request-PDU （无需确认的请求协议数据单元）BACnet-ComplexACK-PDU（复杂的 ACK 命令）BAC net-Error-PDU （报错的协议数据单元）对于上述几种数据的分类主要根据pdu type （下文进行讲解）进行判定。4.1. BAC net-Co nfirmed-Request-PDU 的结构：BAC net-C on firmed-Request-PDU := SEQUENCEpdu-t

10、ype0 Un sig ned (0.15), - 0 for this PDU typesegme nted-message1 BOOLEAN,more-follows2 BOOLEAN,segme nted-resp on se-accepted3 BOOLEAN,4 Un sig ned (0.3), - must be set to zero5 Un sig ned (0.7), - as per 20.1.2.4 Un sig ned (0.15), - as per 20.1.2.57 Un sig ned (0.255),8 Un sig ned (0.255) OPTIONAL

11、, - only if segme nted msg9 Un sig ned (1.127) OPTIONAL, - only if segme nted msg10 BACn etCo nfirmedServiceChoice,11 BACn et-Co nfirmed-Service-Request OPTIONALBIT7BIT6BIT5BIT4BIT3BIT2BIT1BIT0PDU TYPESEGMORSA00Max SegsMax RespInvoke IDSeque nee Number( only prese nt by SEG=1)Proposed Window Size(o

12、nly prese nt by SEG=1)Service ChioceService Request.(BAC net-C on firmed-Service-Request-PDU)(Un segme nted Request)(Segme nted Request)MOR01SA01Max Segs(0.7)Max Resp(0.15)Invoke ID(0.255)Seque nee Number(0.255)(No More Segments Follow)(More Segme nts Follow)(Segme nted Resp onse not accepted)(Segme

13、 nted Resp onse accepted)(Number of resp onse segme nts accepted per 20.1.2.4)(Size of Maximum APDU accepted per 20.1.2.5)Proposed Win dow Size (1.127)Service ChoiceService RequestOnly prese nt if SEG = 1Only prese nt if SEG = 1BAC netCo nfirmedServiceChoiceVariable En codi ngSEG:指出当前的数据单元是否为完整的还是为一

14、部分分段信息MOR :指出是否还有更多的分段信息SA :为1时指出将收到一个复杂的回应(complex ack)Max Segs :指出设备将要接收到多少分段信息B000Un specified n umber of segme nts accepted.B0012 segme nts accepted.B0104 segme nts accepted.B0118 segme nts accepted.B10016 segme nts accepted.B10132 segme nts accepted.B11064 segme nts accepted.B111Greater tha n 6

15、4 segme nts accepted.Max Resp :指出将收到的(APDU )最大长度B0000Up to Mini mumMessageSize (50 octets)B0001Up to 128 octetsB0010Up to 206 octets (fits in a Lon Talk frame)B0011Up to 480 octets (fits in an ARCNET frame)B0100Up to 1024 octetsB0101Up to 1476 octets (fits in an ISO 8802-3 frame)Invoke ID :调用者 IDSer

16、vice Chioce:此处表明次报文的作用，详见BAC netC on firmedServiceChoiceService Request:根据BACnetConfirmedServiceChoice 不同而结构不同，详见BAC net-C on firmed-Service-RequestBAC netCo nfirmedServiceChoice :=枚举类型 -Alarm and Event Servicesack no wledgeAlarm(0),con firmedCOVNotificati on(1),con firmedEve ntNotificati on(2),getA

17、larmSummary(3),getE nrollme ntSummary(4),getEve ntI nformatio n(29),subscribeCOV(5),subscribeCOVProperty(28),lifeSafetyOperati on(27),-File Access ServicesatomicReadFile(6),atomicWriteFile(7),-Object Access ServicesaddListEleme nt(8),removeListEleme nt(9),createObject(10),deleteObject(11),readProper

18、ty(12),readPropertyC on diti onal(13),readPropertyMultiple(14),readRa nge(26),writeProperty(15),writePropertyMultiple(16),oooooooooo o o o o o o o o o o o o o o o o o o o o o上述标记为红色的表示本次应用中所用到的，所以只对这些进行讲解。可以根据BACnetConfirmedServiceChoice找到相对应的 Request或者Ack的数据的结构BACnet-Confirmed-Service-Request := CH

19、OICE/对应上面的 Choice-Alarm and Event Servicesack no wledgeAlarmcon firmedCOVNotificati oncon firmedEve ntNotificati on0 Ack no wledgeAlarm-Request,1 Con firmedCOVNotificati on-Request,2 Con firmedEve ntNotificatio n-Request,-getAlarmSummary con veys no parametersgetE nrollme ntSummary getEve ntI nforma

20、tio n subscribeCOV subscribeCOVProperty lifeSafetyOperati on4 GetE nrollme ntSummary-Request,29 GetEventInformation-Request,5 SubscribeCOV-Request,28 SubscribeCOVProperty-Request,27 LifeSafetyOperatio n-Request,-File Access Services atomicReadFile atomicWriteFile AtomicReadFile-Request,7 AtomicWrite

21、File-Request,-Object Access ServicesaddListEleme nt8 AddListEleme nt-Request,removeListEleme nt createObject deleteObject readProperty readPropertyC on diti onal readPropertyMultiple readRa nge writeProperty writePropertyMultiple读数据请求和读数据回答objectIde ntifier propertyIde ntifier propertyArray In dex (

22、175),(0),(1),(2),9RemoveListEleme nt-Request,10CreateObject-Request,11DeleteObject-Request,12 ReadProperty-Request,13 ReadPropertyCo nditio nal-Request,14 ReadPropertyMultiple-Request,26 ReadRa nge-Request,15 WriteProperty-Request,16 WritePropertyMultiple-Request,oooooooooooo o o o o o o o o o o o o

23、 o o o o o o o o o o o o o o o o o o上述标记为红色的既是针对BACnetConfirmedServiceChoice所用到的数据结构。ReadProperty-Request := SEQUENCE 0 BACnetObjectIdentifier ,1 BACnetPropertyldentifier ,2 Un sig ned OPTIONAL -used only with array datatypeReadPropertyMultiple-Request := SEQUENCElistOfReadAccessSpecs SEQUENCE OF Re

24、adAccessSpecificationReadAccessSpecificati on := SEQUENCEobjectIde ntifier listOfPropertyRefere nces0 BAC netObjectIde ntifier,1 SEQUENCE OF BACnetPropertyRefereneeBAC netPropertyRefere nee := SEQUENCEpropertyIdentifier0 BACnetPropertyldentifier ,propertyArray In dex 1 Un sig ned OPTIONAL -used only

25、 with array datatype -if omitted with an array the en tire array is referenced BAC netPropertylde ntifier := ENUMERATEDaccepted-modes acked-tra nsiti ons ack-required actionacti on-text，active-text，active-vt-sessi ons，active-cov-subscriptio ns(152),adjust-value(176),alarm-value(6),alarm-values(7),al

26、l(8),all-writes-successful(9),apdu-segme nt-timeout(10),apdu-timeout(11),applicati on-software-vers ion(12),firmware-revisi on(44),archive(13),attempted-samples(124),list-of-group-members(53),list-of-object-property-refere nces(54),list-of-sessi on-keys(55),local-date(56),local-time(57),locati on(58

27、),maintenan ce-required(158),man ipulated-variable-refere nee(60),manu al-slave-address-b inding(170),maximum-output(61),maximum-value(135),maximum-value-timestamp(149),max-apdu-le ngth-accepted(62),max-i nfo-frames(63),max-master(64),max-pres-value(65),max-segme nts-accepted(167),member-of(159),min

28、imum-off-time(66),mi nimum-on-time(67),mi nimu m-output(68),even t-state(36),model-name(70),nu mber-of-APDU-retries(73),object-ide ntifier(75),object-list(76),object- name(77),object-property-refere nee(78),object-type(79),operati on-expected(161),opti onal(80),out-of-service(81),output- un its(82),

29、-see even t-parameters(83),polarity(84),prescale(185),prese nt-value(85),priority(86),pulse-rate(186),priority-array(87),priority-for-writ ing(88),protocol-object-types-supported(96),protocol-revisi on(139),protocol-services-supported(97),protocol-vers ion(98),reliability(103),reli nq uish-default(1

30、04),schedule-default(174),segme ntati on-supported(107),state-text(110),status-flags(111),stop-time(143),stop-whe n-full(144),system-status(112),track in g-value(164),units(117),varia nce-value(151),ven dor-ide ntifier(120),vendor-n ame(121),-see database-revisi on(155),上述标记为红色者既是本次应用所用到的属性对象BAC net

31、Objectlde ntifier的编码分为两个部分:Object typeIn sta nee Number占用了 10Bits占用了 22BitsObject Type的表格如下：BAC netObjectTypesSupported := BIT STRING -accumulator(23),an alog-i nput(0),an alog-output(1),an alog-value(2),DEVICE := SEQUENCEobject-ide ntifier object- name object-type system-status vendor-n ame ven dor

32、-ide ntifier model-name firmware-revisi on applicati on-software-vers ion locatio n descripti on protocol-vers ion protocol-revisi on protocol-services-supported protocol-object-types-supported object-listmax-APDU-le ngth-supported segme ntati on-supported vt-classes-supported active-vt-sessi ons lo

33、cal-time local-date utc-offset-averagi ng(18),bin ary-i nput，bin ary-output(4),bin ary-value(5),cale ndar(6),comma nd(7),device(8),eve nt-e nrollme nt(9),file(10),group(11),loop(12),multi-state-i nput(13),multi-state-output(14),-multi-state-value(19),no tificati on-class(15),program(16),设备对象所具备的所有属性

34、及其数据结构如下:75 BACnetObjectIdentifier,77 CharacterString,79 BACn etObjectType,112 BACn etDeviceStatus,121 CharacterStri ng,120 Un sig ned16,70 CharacterStri ng,44 CharacterStri ng,12 CharacterString ,58 CharacterString OPTIONAL,28 CharacterString OPTIONAL,98U nsig ned,139U nsig ned,97 BACn etServicesSu

35、pported,96 BACn etObjectTypesSupported,76 SEQUENCE OF BAC netObjectlde ntifier,-accessed as a BACn etARRAY62 Un sig ned,107 BACn etSegme ntati on,122SEQUENCE OF BAC netVTCIass OPTIONAL,5 SEQUENCE OF BAC netVTSession OPTIONAL, 57 Time OPTIONAL,56 Date OPTIONAL,119 INTEGER OPTIONAL,daylight-savi ngs-s

36、tatus apdu-segme nt-timeout apdu-timeoutnu mber-of-APDU-retries list-of-sessi on-keys time-s yn chro nizatio n-recipie ntsmax-mastermax-i nfo-frames device-address-b inding database-revisi on con figurati on-files last-restore-time backup-failure-timeout active-cov-subscriptio ns max-segme nts-accep

37、ted slave-proxy-e nable auto-slave-discovery slave-address-b indingprofile-n ame24 BOOLEAN OPTIONAL,10 Un sig ned,11 Un sig ned.73 Un sig ned,55 SEQUENCE OF BAC netSessio nKey OPTIONAL,116 SEQUENCE OF BACnetRecipient OPTIONAL,-required for time master64 Un sig ned(1.127) OPTIONAL,-required for MS/TP

38、 master, see 12.1163 Un sig ned OPTIONAL,-required for MS/TP master, see 12.1130 SEQUENCE OF BAC netAddressBi nding,155 Un sig ned,154 SEQUENCE OF BAC netObjectlde ntifier,157 BACn etTimeStamp,153 Un sig ned16,152 SEQUENCE OF BAC netCOVSubscriptio n,167 Un sig ned,172 SEQUENCE OF BOOLEAN OPTIONAL,16

39、9 SEQUENCE OF BOOLEAN OPTIONAL,171SEQUENCE OF BACn etAddressBi ndi ng OPTIONAL,man ual-slave-address-b in di ng 170 SEQUENCE OF BACn etAddressBi ndi ng OPTIONAL,168 CharacterStri ng OPTIONAL上述标记为红色者既是本次应用用到的设备属性对象ANALOG-INPUT := SEQUENCE object-ide ntifier object- name object-type prese nt-value des

40、cripti on device-type status-flags eve nt-state reliability out-of-service update-i nterval units mi n-pres-value max-pres-value resoluti on cov- in creme nt75 BAC netObjectlde ntifier,77 CharacterStri ng,79 BAC netObjectType,85 REAL,28 CharacterString OPTIONAL,31 CharacterStri ng OPTIONAL,111 BACn

41、etStatusFlags,36 BAC netEve ntState,103 BACn etReliability OPTIONAL,81 BOOLEAN,118 Un sig ned OPTIONAL,117 BACn etE ngin eeri ngUn its,69 REAL OPTIONAL,65 REAL OPTIONAL,106 REAL OPTIONAL,22 REAL OPTIONAL,time-delay113 Un sig ned OPTIONAL,no tificati on-class17 Un sig ned OPTIONAL,high-limit45 REAL O

42、PTIONAL,low-limit59 REAL OPTIONAL,deadband25 REAL OPTIONAL,limit-e nable52 BAC netLimitE nable OPTIONAL,eve nt-e nable35 BAC netEve ntTra nsitio nBits OPTIONAL,acked-tra nsiti ons0 BAC netEve ntTra nsitio nBits OPTIONAL,no tify-type72 BAC netNotifyType OPTIONAL,eve nt-time-stamps130 SEQUENCE OF BAC

43、netTimeStamp OPTIONAL,-accessed as a BAC netARRAYprofile-n ame168 CharacterStri ng OPTIONALANALOG-OUTPUT := SEQUENCEobject-ide ntifier75 BAC netObjectlde ntifier,object- name77 CharacterStri ng,object-type79 BAC netObjectType,prese nt-value85 REAL,descripti on28 CharacterString OPTIONAL,device-type3

44、1 CharacterStri ng OPTIONAL,status-flags111 BAC netStatusFlags,even t-state36 BAC netEve ntState,reliability103 BACnetReliability OPTIONAL,out-of-service81 BOOLEAN,units117 BAC netE ngi neeri ngUn its,mi n-pres-value69 REAL OPTIONAL,max-pres-value65 REAL OPTIONAL,resoluti on106 REAL OPTIONAL,priorit

45、y-array87 BAC netPriorityArray,reli nq uish-default104 REAL,cov- in creme nt22 REAL OPTIONAL,time-delay113 Un sig ned OPTIONAL,no tificati on-class17 Un sig ned OPTIONAL,high-limit45 REAL OPTIONAL,low-limit59 REAL OPTIONAL,deadband25 REAL OPTIONAL,limit-e nable52 BAC netLimitE nable OPTIONAL,eve nt-

46、e nable35 BAC netEve ntTra nsitio nBits OPTIONAL,acked-tra nsiti ons0 BACn etEve ntTra nsitio nBits OPTIONAL,no tify-type72 BAC netNotifyType OPTIONAL,eve nt-time-stamps130 SEQUENCE OF BACn etTimeStamp OPTIONAL,-accessed as a BAC netARRAYprofile-n ame168 CharacterString OPTIONALobject-ide ntifier ob

47、ject- name object-type prese nt-value descripti on device-type status-flags eve nt-state reliability out-of-service polarity in active-textANALOG-VALUE := SEQUENCEobject-ide ntifier object- name object-type prese nt-value descripti on status-flags eve nt-state reliability out-of-service units priori

48、ty-array reli nq uish-default cov- in creme nt time-delay no tificati on-class high-limit low-limit deadband limit-e nable eve nt-e nable acked-tra nsiti ons no tify-type eve nt-time-stamps75 BACn etObjectIde ntifier,77 CharacterStri ng,79 BACn etObjectType,85 REAL,28 CharacterString OPTIONAL,111 BA

49、Cn etStatusFlags,36 BACn etEve ntState,103 BACn etReliability OPTIONAL,81 BOOLEAN,117 BACn etE ngi neeri ngUni ts,87 BACn etPriorityArray OPTIONAL,104 REAL OPTIONAL,22 REAL OPTIONAL,113 Un sig ned OPTIONAL,17 Un sig ned OPTIONAL,45 REAL OPTIONAL,59 REAL OPTIONAL,25 REAL OPTIONAL,52 BACn etLimitE nab

50、le OPTIONAL,35 BACn etEve ntTra nsitio nBits OPTIONAL,0 BAC netEve ntTra nsitio nBits OPTIONAL,72 BACn etNotifyType OPTIONAL,130 SEQUENCE OF BAC netTimeStamp OPTIONAL,-accessed as a BAC netARRAYprofile-n ame168 CharacterStri ng OPTIONALBINARY-INPUT := SEQUENCE75 BACnetObjectldentifier,77 CharacterSt

51、ri ng,79 BAC netObjectType,85 BAC netBi naryPV,28 CharacterString OPTIONAL,31 CharacterStri ng OPTIONAL,111BAC netStatusFlags,36 BAC netEve ntState,103 BACnetReliability OPTIONAL,81 BOOLEAN,84 BAC netPolarity,46 CharacterString OPTIONAL,active-text4 CharacterString OPTIONAL,cha nge-of-state-time16 B

52、ACnetDateTime OPTIONAL,cha nge-of-state-co unt15 Un sig ned OPTIONAL,time-of-state-co un t-reset115 BACn etDateTime OPTIONAL,elapsed-active-time33 Un sig ned32 OPTIONAL,time-of-active-time-reset114 BACn etDateTime OPTIONAL,time-delay113 Un sig ned OPTIONAL,no tificati on-class17 Un sig ned OPTIONAL,

53、alarm-value6 BAC netBi naryPV OPTIONAL,eve nt-e nable35 BAC netEve ntTra nsitio nBits OPTIONAL,acked-tra nsiti ons0 BAC netEve ntTra nsitio nBits OPTIONAL,no tify-type72 BAC netNotifyType OPTIONAL,eve nt-time-stamps130 SEQUENCE OF BAC netTimeStamp OPTIONAL,-accessed as a BAC netARRAYprofile-n ame168

54、 CharacterStri ng OPTIONALBINARY-OUTPUT := SEQUENCEobject-ide ntifier75 BAC netObjectlde ntifier,object- name77 CharacterStri ng,object-type79 BAC netObjectType,prese nt-value85 BAC netB in aryPV,descripti on28 CharacterString OPTIONAL,device-type31 CharacterStri ng OPTIONAL,status-flags111BAC netSt

55、atusFlags,even t-state36 BAC netEve ntState,reliability103BACnetReliability OPTIONAL,out-of-service81 BOOLEAN,polarity84 BAC netPolarity,in active-text46 CharacterString OPTIONAL,active-text4 CharacterString OPTIONAL,cha nge-of-state-time16 BACnetDateTime OPTIONAL,cha nge-of-state-co unt15 Un sig ne

56、d OPTIONAL,time-of-state-co un t-reset115 BACn etDateTime OPTIONAL,elapsed-active-time33 Un sig ned32 OPTIONAL,time-of-active-time-reset114 BACn etDateTime OPTIONAL,minimum-off-time66 Un sig ned32 OPTIONAL,mi nimum-on-time67 Un sig ned32 OPTIONAL,priority-array87 BAC netPriorityArray,reli nq uish-de

57、fault104 BACn etB in aryPV,time-delay113 Un sig ned OPTIONAL,no tificati on-class17 Un sig ned OPTIONAL,feedback-value40 BAC netBi naryPV OPTIONAL,eve nt-e nable35 BAC netEve ntTra nsitio nBits OPTIONAL,object-ide ntifier object- name object-typeacked-tra nsiti ons no tify-type eve nt-time-stamps0 B

58、AC netEve ntTra nsitio nBits OPTIONAL,72 BAC netNotifyType OPTIONAL,130 SEQUENCE OF BAC netTimeStamp OPTIONAL,-accessed as a BAC netARRAYprofile-n ame168 CharacterStri ng OPTIONALBINARY-V ALUE := SEQUENCEobject-ide ntifier object- name object-type prese nt-value descripti on status-flags eve nt-stat

59、e reliability out-of-service in active-text active-text cha nge-of-state-time cha nge-of-state-co unt time-of-state-co un t-reset elapsed-active-time time-of-active-time-reset minimum-off-time mi nimum-on-time priority-array reli nq uish-default time-delay no tificati on-class alarm-value eve nt-e n

60、able acked-tra nsiti ons no tify-type eve nt-time-stamps75 BAC netObjectlde ntifier,77 CharacterStri ng,79 BAC netObjectType,85 BAC netB in aryPV,28 CharacterString OPTIONAL,111 BACn etStatusFlags,36 BAC netEve ntState,103 BACn etReliability OPTIONAL,81 BOOLEAN,46 CharacterString OPTIONAL,4 Characte