BACnet (Building Automation Control Network) Standard
BACnet is a standard communication protocol as defined in ANSI/ASHRAE
Standard 135-1995. The BACnet protocol has many applications in light and
commercial buildings including HVAC control and management.
BACnet protocol is a set of rules that govern data flow and
allows for intercommunication among devices on a network irrespective of the
manufacturer/vendor.
See below various HVAC systems interconnected to a BMS
system for central control.
BACnet operates on two main concepts:
BACnet
services: for information purposes
BACnet
objects: for action i.e reading, writing, or performing functions on the
devices.
BACnet generally have two types of networks:
- BACnet MS/TP
(Master-Slave/Token Passing)- protocol uses standard serial ports
(RS-232/RS-485) on microcontrollers. Utilizes token-passing process from one
master node to another (makes its communication slow).

In case you may be having issues
with your BACnet MS/TP, here is an
example of how to troubleshoot issues.

Alternative to wired BACnet MS/TP,
you can use
wireless
BACnet (or
Wireless
Modbus) to ease you setup and reduce troubleshooting time in case of issues.
- BACnet TCP/IP
(Internet Protocol)- operates in IP-enabled devices. More and more new
controllers and devices on the market are IP-enabled, including but not limited
to actuators, sensors, light switches, gateways, cameras, and thermostats.
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