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4.Functional s
p
ecification
4.1 Communication Protocol Specification
1) Protocol Outline
BACnet/IP which applied to ANSI/ASHRAE 135-1995, 135a, 135b correspondingly on UDP/IP
of Ethernet is used.
APDU of BACnetNPCIof BACnetNETWORK
BVLL HeaderUDP Header IP Header Ether Header
2) Ether Header
A physical layer sets a transmission medium to 10 BASET by Ethernet.
3) IP Header
The private address of Class C is recommended (*1). Subnet mask 255.255.255.0
*1: Recommendation value (range) [192.168.1.1]～[192.168.254.254]
[192.168.0.0] and [192.168.255.255] do not use it.
4) UDP Header
The default UDP port of a unicast and broadcasting is set to 47808 (OxBAC0).
5) BVLL Header
BVLC type (one octet) 0x81 fixation (BVLL to BACnet/IP)
BVLC function (one octet) 0x0A At the time of a unicast
0x0B At the time of broadcasting
BVLC length (two octets) Arbitrary (wording-of-a-telegram length setup: a big endian specification)
6) NPCI of BACnetNETWORK
Version (one octet) 0x01 Fixation
Control (one octet) 0x04 Those with a response message
0x00 With no response message
7) APDU of BACnet
It has arbitrary lengths of 1024 or less octets. Contents details are ANSI/ASHRAE135-1995, 135a, 135b
references.
8)Application of BACnet
・The instance number of a Device object 3(Setting change of a instance number is possible)
・Segmentation Transmission and reception are un-supported.
・APDU which can be received 1024 octet
・APDU timeout 3 sec(Setting change of a instance number is possible)
・Vender ID 99
・Process ID blank (Setting change of a process ID is possible)
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