User Guide
Honeywell • 8 BACNET TECHNICAL DATA
3. BACNET TECHNICAL DATA
3.1 BACnet MS/TP protocol
3.2 BACnet IP protocol
3.3 ACD (Address Conflict Detection)
The SmartVFD HVAC/SmartDrive HVAC AC drives implement the ACD algorithm (IETF RFC
5227).
The ACD algorithm tries to actively detect if the IP address configured to this device is been
used by another device in the same network. To accomplish this, ACD sends four ARP request
packets when the device's Ethernet interface goes up or when its IP address changes. ACD
prevents the use of the Ethernet interface until the ARP probing finishes. This delays the start-
up of fieldbus protocols about one second. During the delay or after it, the ACD passively
checks incoming ARP messages for use of the device's IP address.
If another device with the same IP address is detected, the ACD will try to defend its IP address
with a single ARP message. If the other device with the same IP address also supports ACD,
it should stop using the address. If not, the ACD will close the Ethernet connection and indicate
the situation with an Alarm. This is done according the "DefendWithPolicyB". Acknowledging
of the Alarm is not possible if the problem is active. ACD opens Ethernet connection if the other
device with the same IP address disappears from the network. Alarm can be acknowledged
after this. Other policies are not supported. If the fieldbus protocol has been active, a fieldbus
fault may be activated (depends on the fieldbus and drive application configuration).
Table 1.
Connections and
communications
Interface RS-485
Data transfer method RS-485 MS/TP, half-duplex
Transfer cable STP (Shielded Twisted Pair), type Belden
9841 or similar
Connector
2.5 mm
2
Electrical isolation Functional
BACnet MS/TP As described in ANSI/ASHRAE Standards
135-2010 Ver.1 Rev.12
Baud rate 9600, 19200, 38400 and 76800 baud(sup-
ports autobaud detection)
Table 2.
Connections and
communications
Interface 100BaseTX, IEEE 802.3 compatible
Data transfer method Ethernet half/full -duplex
Data transfer speed 10/100 MBit/s, autosensing
Protocol BACnet over UDP/IP
Connector Shielded RJ45 connector.
Cable type CAT5e STP
BACnet IP As described in ANSI/ASHRAE Standards
135-2010 Ver.1 Rev.12
IP address mode Selectable: Static or DHCP