资源描述
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网络层与某指定得通讯子系统得接口,本文指定了BACnet虚拟链路控制(BVLC)要求支持得定向与广播信息。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网络层与BACnet应用层。B/IP提供了TCP/IP一样得通讯结构,采用UDP得通讯方式。本文接下来将对此三层结构进行详细得讲解。
其文本协议得大致格式如下:
BACnet/IP
BACnet网络层
BACnet 应用层
BVLC Type
BVLC Function
Length
NPDU
APDU
NPDU:BACnet网络层数据结构,下文进行详细得讲解
APDU:BACnet应用层数据结构,下文进行详细得讲解
2、BACnet/IP、
ﻩBVLC Type:ﻩ 0x81,代表BACnet/IP网络
BVLC Function:ﻩ指定报文得类型,何种作用;本应用使用得报文类型分为两种:
ﻩ 0A:点对点通讯
0B:广播通信
Length:ﻩ 指定报文得长度,包括BVLC Type、BVLC Function以及本身在内ﻩNPDU: ﻩ 根据不同情况,报文长短不同,见下文得解析。
APDU:ﻩﻩﻩ根据NPDU不同以及不同得请求,报文不同,见下文得解析。ﻩ
3、BACnet NPDU结构、
版本信息
1 Byte
Version
控制字
1 Byte
Control
目标网络号
2 Bytes
DNET
目标网络长度
1 Byte
DLEN
目标地址
可变长度
DADR
原网络号
2 Bytes
SNET
原网络长度
1 Byte
SLEN
原地址
可变
SNET
路由数目
1 Byte
Hop Count
消息类型
1 Byte
Message Type
卖方ID
2 Bytes
Vendor ID
应用层信息
可变
APDU
版本信息 :默认0x01
控制字ﻩﻩ:BIT7:1表示Message Type存在,为0时Message Type不存在
ﻩ BIT6:保留,为0
ﻩ BIT5:1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
ﻩ BIT4:保留,为0
ﻩ BIT3:1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
ﻩ BIT2:1表示为一个需确认得请求数据单元,一复杂ACK数据单元或一网络层
信息非reply得;0表示除去上述情形得数据单元
ﻩﻩ BIT1、0:网络优先级
ﻩﻩ ﻩ11 = Life Safety message
10 = Critical Equipment message
01 = Urgent message
00 = Normal message
目标网络号:FFFF得时候表示广播
目标长度: 表示DADR得长度
目标地址: 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得长度
原地址: 原网络得MAC地址
路由数目: 数据需要经过得路由个数,当不存在DNET得时候,需设置为FF
消息类型: X'00': Who-Is-Router-To-Network
X'01': I-Am-Router-To-Network
X'02': I-Could-Be-Router-To-Network
X'03': Reject-Message-To-Network
X'04': Router-Busy-To-Network
X'05': Router-Available-To-Network
X'06': Initialize-Routing-Table
X'07': Initialize-Routing-Table-Ack
X'08': Establish-Connection-To-Network
X'09': Disconnect-Connection-To-Network
X'0A' to X'7F': Reserved for use by ASHRAE
X'80' to X'FF': Available for vendor proprietary messages
卖方ID:ﻩ当控制字得BIT7为1并且消息类型为X'80' to X'FF':得时候,才会存在
ﻩﻩﻩ本次开发没有用到,不再解释
本次应用中控制字只用到0x20与0x04两种,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:
BACnetPDU ::= CHOICE
{
confirmed-request-PDU [0] BACnet-Confirmed-Request-PDU,
unconfirmed-request-PDU ﻩ[1] BACnet-Unconfirmed-Request-PDU,
simpleACK-PDU [2] BACnet-SimpleACK-PDU,
plexACK-PDU [3] BACnet-plexACK-PDU,
segmentAck-PDU [4] BACnet-SegmentACK-PDU,
error-PDU [5] BACnet-Error-PDU,
reject-PDU [6] BACnet-Reject-PDU,
abort-PDU ﻩ [7] BACnet-Abort-PDU
}
对于本次应用,主要用到了
BACnet-Confirmed-Request-PDU(需确认得请求协议数据单元)
BACnet-Unconfirmed-Request-PDU(无需确认得请求协议数据单元)
BACnet-plexACK-PDU(复杂得ACK命令)
BACnet-Error-PDU(报错得协议数据单元)
对于上述几种数据得分类主要根据pdu type(下文进行讲解)进行判定。
4、1、 BACnet-Confirmed-Request-PDU得结构:
BACnet-Confirmed-Request-PDU ::= SEQUENCE
{
pdu-type ﻩ ﻩﻩ [0] Unsigned (0、、15), -- 0 for this PDU type
segmented-message ﻩ [1] BOOLEAN,
more-follows ﻩ ﻩ[2] BOOLEAN,
segmented-response-accepted [3] BOOLEAN,
reserved ﻩ ﻩ [4] Unsigned (0、、3), -- must be set to zero
max-segments-accepted [5] Unsigned (0、、7), -- as per 20.1.2、4
max-APDU-length-accepted [6] Unsigned (0、、15), -- as per 20.1.2、5
invokeID ﻩﻩﻩﻩ[7] Unsigned (0、、255),
sequence-number ﻩ [8] Unsigned (0、、255) OPTIONAL, -- only if segmented msg
proposed-window-size [9] Unsigned (1、、127) OPTIONAL, -- only if segmented msg
service-choice ﻩ[10] BACnetConfirmedServiceChoice,
service-request ﻩﻩ[11] BACnet-Confirmed-Service-Request OPTIONAL
}
BIT7
BIT6
BIT5
BIT4
BIT3
BIT2
BIT1
BIT0
PDU TYPE
SEG
MOR
SA
0
0
Max Segs
Max Resp
Invoke ID
Sequence Number(only present by SEG==1)
Proposed Window Size(only present by SEG==1)
Service Chioce
Service Request……
PDU Type ﻩ0 (BACnet-Confirmed-Service-Request-PDU)
SEG ﻩ ﻩﻩ0 (Unsegmented Request)
1 ﻩﻩﻩ(Segmented Request)
MOR ﻩ0 ﻩ (No More Segments Follow)
1 ﻩﻩ(More Segments Follow)
SA ﻩ ﻩ 0 ﻩﻩ(Segmented Response not accepted)
1ﻩﻩ (Segmented Response accepted)
Max Segs ﻩﻩ(0、、7) ﻩﻩ(Number of response segments accepted per 20.1.2、4)
Max Resp ﻩﻩ(0、、15) ﻩ (Size of Maximum APDU accepted per 20.1.2、5)
Invoke ID ﻩ (0、、255)
Sequence Numberﻩ (0、、255) Only present if SEG = 1
Proposed Window Size ﻩ(1、、127) ﻩOnly present if SEG = 1
Service Choice ﻩﻩBACnetConfirmedServiceChoice
Service Request ﻩ ﻩVariable Encoding
SEG:指出当前得数据单元就是否为完整得还就是为一部分分段信息
MOR:指出就是否还有更多得分段信息
SA: 为1时指出将收到一个复杂得回应(plex ack)
Max Segs :指出设备将要接收到多少分段信息
ﻩﻩB'000' ﻩUnspecified number of segments accepted、
B'001' 2 segments accepted、
B'010' 4 segments accepted、
B'011' 8 segments accepted、
B'100' ﻩ16 segments accepted、
B'101' ﻩ32 segments accepted、
B'110' 64 segments accepted、
B'111' Greater than 64 segments accepted、
Max Resp:指出将收到得(APDU)最大长度
B'0000' Up to MinimumMessageSize (50 octets)
B'0001' ﻩUp to 128 octets
B'0010' Up to 206 octets (fits in a LonTalk frame)
B'0011' Up to 480 octets (fits in an ARCNET frame)
B'0100' ﻩUp to 1024 octets
B'0101' ﻩUp to 1476 octets (fits in an ISO 8802-3 frame)
Invoke ID:调用者ID
Service Chioce:此处表明次报文得作用,详见BACnetConfirmedServiceChoice
Service Request:根据BACnetConfirmedServiceChoice不同而结构不同,详见
BACnet-Confirmed-Service-Request
BACnetConfirmedServiceChoice ::= 枚举类型
{
-- Alarm and Event Services
acknowledgeAlarm ﻩﻩ (0),
confirmedCOVNotification (1),
confirmedEventNotification ﻩ(2),
getAlarmSummary ﻩ(3),
getEnrollmentSummary (4),
getEventInformation (29),
subscribeCOV ﻩﻩ (5),
subscribeCOVProperty (28),
lifeSafetyOperation (27),
-- Services
atomicReadFile ﻩﻩ ﻩ(6),
atomicWriteFile ﻩ ﻩ(7),
-- Object Access Services
addListElement ﻩ ﻩﻩ(8),
removeListElement ﻩﻩ (9),
createObject ﻩﻩﻩ(10),
deleteObject ﻩ ﻩ(11),
readProperty ﻩ (12),
readPropertyConditional ﻩﻩ(13),
readPropertyMultiple ﻩ (14),
readRange ﻩ (26),
writeProperty ﻩ ﻩﻩ(15),
writePropertyMultiple (16),
。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
}
上述标记为红色得表示本次应用中所用到得,所以只对这些进行讲解。
可以根据BACnetConfirmedServiceChoice找到相对应得Request或者Ack得数据得结构
BACnet-Confirmed-Service-Request ::= CHOICE ﻩ ﻩ//对应上面得Choice
{
-- Alarm and Event Services
acknowledgeAlarm ﻩ[0] AcknowledgeAlarm-Request,
confirmedCOVNotification ﻩ[1] ConfirmedCOVNotification-Request,
confirmedEventNotification ﻩ [2] ConfirmedEventNotification-Request,
-- getAlarmSummary conveys no parameters
getEnrollmentSummary [4] GetEnrollmentSummary-Request,
getEventInformation ﻩ[29] GetEventInformation-Request,
subscribeCOV ﻩ ﻩ [5] SubscribeCOV-Request,
subscribeCOVProperty [28] SubscribeCOVProperty-Request,
lifeSafetyOperation ﻩ[27] LifeSafetyOperation-Request,
-- Services
atomicReadFile ﻩ ﻩﻩ[6] AtomicRead,
atomicWriteFile ﻩﻩﻩ[7] AtomicWrite,
-- Object Access Services
addListElement ﻩ ﻩﻩ[8] AddListElement-Request,
removeListElement ﻩﻩ [9] RemoveListElement-Request,
createObject ﻩ [10] CreateObject-Request,
deleteObject ﻩﻩﻩﻩﻩ[11] DeleteObject-Request,
readProperty ﻩ ﻩ ﻩ[12] ReadProperty-Request,
readPropertyConditional ﻩ[13] ReadPropertyConditional-Request,
readPropertyMultiple ﻩﻩﻩ[14] ReadPropertyMultiple-Request,
readRange ﻩﻩ [26] ReadRange-Request,
writeProperty ﻩ ﻩ [15] WriteProperty-Request,
writePropertyMultiple ﻩﻩ[16] WritePropertyMultiple-Request,
。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
}
上述标记为红色得既就是针对BACnetConfirmedServiceChoice所用到得数据结构。
ReadProperty-Request ::= SEQUENCE ﻩ ﻩﻩ//读数据请求与读数据回答
{
objectIdentifier ﻩ[0] BACnetObjectIdentifier,
propertyIdentifier ﻩ [1] BACnetPropertyIdentifier,
propertyArrayIndex [2] Unsigned OPTIONAL --used only with array datatype
}
ReadPropertyMultiple-Request ::= SEQUENCE
{
listOfReadAccessSpecs SEQUENCE OF ReadAccessSpecification
}
ReadAccessSpecification ::= SEQUENCE
{
objectIdentifier ﻩ [0] BACnetObjectIdentifier,
listOfPropertyReferences [1] SEQUENCE OF BACnetPropertyReference
}
BACnetPropertyReference ::= SEQUENCE
{
propertyIdentifier ﻩ[0] BACnetPropertyIdentifier,
propertyArrayIndex [1] Unsigned OPTIONAL --used only with array datatype
-- if omitted with an array the entire array is referenced
}
BACnetPropertyIdentifier ::= ENUMERATED
{
accepted-modes ﻩ ﻩﻩ(175),
acked-transitions ﻩ (0),
ack-required ﻩﻩ ﻩﻩ(1),
action ﻩ ﻩﻩ(2),
action-text ﻩﻩﻩ ﻩ(3),
active-text ﻩﻩﻩﻩ (4),
active-vt-sessions ﻩ(5),
active-cov-subscriptions (152),
adjust-value ﻩ(176),
alarm-value ﻩﻩ (6),
alarm-values ﻩ (7),
all ﻩ ﻩﻩ(8),
all-writes-successful ﻩﻩﻩ(9),
apdu-segment-timeout ﻩ (10),
apdu-timeout ﻩﻩﻩ ﻩ(11),
application-software-version ﻩﻩ(12),
firmware-revision ﻩﻩ (44),
archive ﻩ ﻩﻩ(13),
attempted-samples ﻩ ﻩ (124),
list-of-group-members ﻩﻩ (53),
list-of-object-property-references (54),
list-of-session-keys ﻩﻩ(55),
local-date ﻩ ﻩﻩﻩ(56),
local-time ﻩ (57),
location ﻩﻩﻩﻩﻩ (58),
maintenance-required ﻩ ﻩ(158),
manipulated-variable-reference ﻩ(60),
manual-slave-address-binding (170),
maximum-output ﻩ ﻩ (61),
maximum-value ﻩﻩﻩ (135),
maximum-value-timestamp ﻩﻩ(149),
max-apdu-length-accepted ﻩﻩ(62),
max-info-frames ﻩ ﻩ(63),
max-master ﻩﻩ ﻩﻩ(64),
max-pres-value ﻩ (65),
max-segments-accepted ﻩ (167),
member-of ﻩ ﻩﻩ (159),
minimum-off-time ﻩﻩ ﻩ(66),
minimum-on-time ﻩ ﻩﻩ(67),
minimum-output ﻩﻩ (68),
event-state ﻩﻩﻩ (36),
model-name ﻩﻩﻩﻩﻩ(70),
number-of-APDU-retries ﻩ(73),
object-identifier ﻩ ﻩﻩ (75),
object-list ﻩﻩ ﻩﻩ(76),
object-name ﻩﻩ ﻩﻩ(77),
object-property-reference ﻩ (78),
object-type ﻩ ﻩﻩ (79),
operation-expected ﻩﻩﻩ(161),
optional ﻩ ﻩ ﻩ (80),
out-of-service ﻩﻩﻩﻩﻩ(81),
output-units ﻩ (82),
-- see event-parameters ﻩﻩﻩ (83),
polarity ﻩﻩ ﻩﻩ (84),
prescale ﻩﻩ(185),
present-value ﻩ ﻩ(85),
priority ﻩﻩ ﻩ (86),
pulse-rate ﻩ ﻩ ﻩ(186),
priority-array ﻩﻩﻩ ﻩ(87),
priority-for-writing ﻩ ﻩﻩ(88),
protocol-object-types-supported (96),
protocol-revision ﻩﻩﻩ(139),
protocol-services-supported ﻩﻩ(97),
protocol-version ﻩ ﻩﻩ(98),
reliability ﻩ ﻩ ﻩﻩ(103),
relinquish-default ﻩ ﻩ(104),
schedule-default ﻩ ﻩ(174),
segmentation-supported ﻩ(107),
state-text ﻩﻩﻩﻩ (110),
status-flags ﻩ ﻩﻩ (111),
stop-time ﻩ (143),
stop-when-full ﻩﻩﻩ ﻩ(144),
system-status ﻩﻩ ﻩﻩ(112),
tracking-value ﻩﻩﻩ (164),
units ﻩ ﻩ (117),
variance-value ﻩ ﻩ(151),
vendor-identifier ﻩ ﻩ (120),
vendor-name ﻩﻩﻩ (121),
-- see database-revision ﻩ ﻩ(155),
}
上述标记为红色者既就是本次应用所用到得属性对象
BACnetObjectIdentifier得编码分为两个部分:
Object type
Instance Number
占用了10Bits
占用了22Bits
Object Type得表格如下:
BACnetObjectTypesSupported ::= BIT STRING
{
-- accumulator ﻩﻩ(23),
analog-input ﻩ (0),
analog-output ﻩﻩ(1),
analog-value ﻩﻩ(2),
-- averaging ﻩ (18),
binary-input ﻩﻩ(3),
binary-output ﻩﻩ(4),
binary-value ﻩ ﻩ(5),
calendar ﻩﻩﻩ(6),
mand ﻩﻩ (7),
device (8),
event-enrollment ﻩ(9),
file ﻩﻩ ﻩ(10),
group ﻩﻩﻩﻩ(11),
loop ﻩﻩﻩ(12),
multi-state-input (13),
multi-state-output ﻩ(14),
-- multi-state-value ﻩ(19),
notification-class ﻩ(15),
program ﻩﻩ (16),
}
设备对象所具备得所有属性及其数据结构如下:
DEVICE ::= SEQUENCE
{
object-identifier ﻩﻩﻩ [75] BACnetObjectIdentifier,
object-name ﻩﻩ [77] CharacterString,
object-type ﻩﻩﻩﻩ [79] BACnetObjectType,
system-status ﻩ [112] BACnetDeviceStatus,
vendor-name [121] CharacterString,
vendor-identifier ﻩﻩ[120] Unsigned16,
model-name ﻩﻩﻩ [70] CharacterString,
firmware-revision ﻩ ﻩﻩ[44] CharacterString,
application-software-version ﻩ[12] CharacterString,
location ﻩﻩ [58] CharacterString OPTIONAL,
description ﻩﻩﻩﻩ[28] CharacterString OPTIONAL,
protocol-version ﻩﻩﻩ [98]Unsigned,
protocol-revision ﻩ [139]Unsigned,
protocol-services-supported ﻩ[97] BACnetServicesSupported,
protocol-object-types-supported [96] BACnetObjectTypesSupported,
object-list ﻩ [76] SEQUENCE OF BACnetObjectIdentifier,
ﻩ -- accessed as a BACnetARRAY
max-APDU-length-supported [62] Unsigned,
segmentation-supported ﻩﻩ[107] BACnetSegmentation,
vt-classes-supported ﻩﻩﻩ[122] SEQUENCE OF BACnetVTClass OPTIONAL,
active-vt-sessions ﻩ ﻩ[5] SEQUENCE OF BACnetVTSession OPTIONAL,
local-time ﻩﻩﻩ ﻩ[57] Time OPTIONAL,
local-date ﻩﻩﻩﻩ[56] Date OPTIONAL,
utc-offset ﻩﻩ ﻩ[119] INTEGER OPTIONAL,
daylight-savings-status [24] BOOLEAN OPTIONAL,
apdu-segment-timeout ﻩ[10] Unsigned,
apdu-timeout ﻩ ﻩﻩ [11] Unsigned,
number-of-APDU-retries ﻩ[73] Unsigned,
list-of-session-keys ﻩﻩ[55] SEQUENCE OF BACnetSessionKey OPTIONAL,
time-synchronization-recipients ﻩ[116] SEQUENCE OF BACnetRecipient OPTIONAL,
-- required for time master
max-master ﻩ ﻩ [64] Unsigned(1、、127) OPTIONAL,
-- required for MS/TP master, see 12、11
max-info-frames ﻩﻩﻩﻩ[63] Unsigned OPTIONAL,
-- required for MS/TP master, see 12、11
device-address-binding ﻩ [30] SEQUENCE OF BACnetAddressBinding,
database-revision ﻩ [155] Unsigned,
configuration-files ﻩﻩ ﻩ[154] SEQUENCE OF BACnetObjectIdentifier,
last-restore-time ﻩ [157] BACnetTimeStamp,
backup-failure-timeout ﻩ [153] Unsigned16,
active-cov-subscriptions ﻩﻩ[152] SEQUENCE OF BACnetCOVSubscription,
max-segments-accepted ﻩ [167] Unsigned,
slave-proxy-enable ﻩﻩ [172] SEQUENCE OF BOOLEAN OPTIONAL,
auto-slave-discovery ﻩ [169] SEQUENCE OF BOOLEAN OPTIONAL,
slave-address-binding ﻩﻩ[171]SEQUENCE OF BACnetAddressBinding OPTIONAL,
manual-slave-address-binding [170] SEQUENCE OF BACnetAddressBinding OPTIONAL,
pro ﻩﻩ ﻩ[168] CharacterString OPTIONAL
}
上述标记为红色者既就是本次应用用到得设备属性对象
ANALOG-INPUT ::= SEQUENCE
{
object-identifier ﻩ [75] BACnetObjectIdentifier,
object-name ﻩﻩﻩ [77] CharacterString,
object-type ﻩﻩﻩ [79] BACnetObjectType,
present-value ﻩﻩﻩ [85] REAL,
description ﻩ ﻩ [28] CharacterString OPTIONAL,
device-type ﻩ [31] CharacterString OPTIONAL,
status-flags ﻩ [111] BACnetStatusFlags,
event-state ﻩ ﻩﻩ[36] BACnetEventState,
reliability ﻩ ﻩﻩ[103] BACnetReliability OPTIONAL,
out-of-service ﻩﻩ [81] BOOLEAN,
update-interval ﻩﻩ[118] Unsigned OPTIONAL,
units ﻩ [117] BACnetEngineeringUnits,
min-pres-value ﻩﻩ[69] REAL OPTIONAL,
max-pres-value ﻩﻩﻩ[65] REAL OPTIONAL,
resolution ﻩ [106] REAL OPTIONAL,
cov-increment ﻩﻩﻩ[22] REAL OPTIONAL,
time-delay ﻩﻩ [113] Unsigned OPTIONAL,
notification-class [17] Unsigned OPTIONAL,
high-limit ﻩﻩ [45] REAL OPTIONAL,
low-limit ﻩﻩ ﻩ[59] REAL OPTIONAL,
deadband ﻩﻩ [25] REAL OPTIONAL,
limit-enable ﻩﻩﻩﻩ[52] BACnetLimitEnable OPTIONAL,
event-enable ﻩ [35] BACnetEventTransitionBits OPTIONAL,
acked-transitions ﻩ ﻩ[0] BACnetEventTransitionBits OPTIONAL,
notify-type ﻩﻩﻩﻩ[72] BACnetNotifyType OPTIONAL,
event-time-stamps ﻩ ﻩ[130] SEQUENCE OF BACnetTimeStamp OPTIONAL,
-- accessed as a BACnetARRAY
pro ﻩﻩ[168] CharacterString OPTIONAL
}
ANALOG-OUTPUT ::= SEQUENCE
{
object-identifier [75] BACnetObjectIdentifier,
object-name ﻩ [77] CharacterString,
object-type [79] BACnetObjectType,
present-value ﻩ[85] REAL,
description ﻩ[28] CharacterString OPTIONAL,
device-type ﻩﻩ[31] CharacterString OPTIONAL,
status-flags ﻩﻩ[111] BACnetStatusFlags,
event-state [36]
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