IM 916-5 • MICROTECH COMMUNICATION MODULE 10 www.DaikinApplied.com
Appendix A: BACnet IP Networks
Appendix A: BACnet IP Networks
BACnet IP Network Types
Single IP Subnet
In BACnet/IP networks with only IP subnet (IP domain),
broadcast messages from a device (ex. 172.16.255.255 or
0xBAC0) are sent to all other subnet members as IP broadcasts
without requiring any additional configuration.
DHCP Networks
BACnet IP networks with DHCP use a server (typically a router
or gateway) to automatically request network configuration
parameters, such as IP addresses, to all devices. DHCP-
enabled networks eliminate the need for a user to configure
these settings manually since IP Addresses and other
parameters are determined dynamically by the server.
There are several important aspects to consider with DHCP-
enabled networks:
Aspect
Considerations
BBMDs
DHCP
can not
be used together with BBMDs,
as the IP addresses are configured as static
addresses and cannot change during operation.
Alarm
recipient
In BACnet, alarm recipients are entered with
their “Device Object Identifier” or their BACnet
address. The IP address is part of the BACnet
address and may not be changed for the alarm
recipient. For this reason, option “Device Object
Identifier” must always be used.
Access
rights
If access rights are assigned based on IP
address, such as firewalls, the address must
be static. Access rights are based off of the
UDP Port Number (ex. UDP 47808) or the MAC
Address of the BACnet communication module.
IP version
The BACnet communication module supports
IP Version 4, (i.e. IP devices with 32 bit
addresses).
Multiple IP Subnets
A BACnet/IP network may consist of multiple IP subnets
assigned the same BACnet network number. In this case,
a BBMD (BACnet Broadcast Management Device) allows
broadcasts to be transmitted to all other BBMDs on the BACnet
network. BBMDs allow devices on one network to distribute
broadcasts, or communicate, across multiple subnets. A
BBMD also provides for foreign device registration. This allows
a device on one network to communicate with a device on
another network by using the BBMD to forward and route the
messages.
The BACnet communication module can be registered as
a BBMD device. This is done by registering the IP Address
and subnet mask of the communication module as a Foreign
Device with the BBMD.
Summary of Contents for BACnet MT3041
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