Installation & Operation Manual - Model AVC5000
Contents of this Manual are Subject to Change Without Notification Page 52
SECTION 7 – BACnet
BACnet® is a standard data communication protocol designed specifically for building
automation and control networks. The AVC controller uses the BACnet MS/TP (Master-
Slave/Token Passing) protocol which is a type of MAC layer implemented using the EIA-485
signaling standard. The performance of the MS/TP network is heavily influenced by the
network traffic load, the assignment of MS/TP node addresses and the network configuration
parameter Nmax_info_frames. Additionally, it is imperative the physical network layer is
properly configured (cabling, EOL terminations, bias, etc...) and is verified to be reliable
otherwise the network performance can be compromised. Due to the complexities associated
with network communications, the most reliable method for communicating the airflow set
point to the AVC controller is via Analog Signal.
Caution: Though the AVC controller is fully capable of using BACnet as a means to
receive the airflow set point, Accutrol does not recommended doing this for applications
which require high speed and/or critical airflow control including tracking pair
applications and VAV control.
7.1 BACnet Objects
The AVC AccuValve supports a collection of BACnet-visible objects. In addition to a Device
object whose instance is programmed by writing to the current Object_Identifier or the
“wildcard” Object_Identifier whose instance is 4194303, the AVC supports several standard
object types as described herein. The following table defines the visible objects. The PV column
indicates whether the Present_Value is Read Only “R”, Writable “W” or a Commanded “C”
point.
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