BACnet  Building Automation and Control Network — BACnet is a communications protocol for building automation and control networks. It is an ASHRAE, ANSI, and ISO standard protocol.

The intent of this open standard allows an integrator to pick and choose BACnet-compliant equipment from various vendors.

BACnet was designed to allow communication of building automation and control systems for applications such as heating, ventilating, and air-conditioning control, lighting control, access control, and fire detection systems and their associated equipment. The BACnet protocol provides mechanisms for computerized building automation devices to exchange information, regardless of the particular building service they perform.

BACnet devices communicate to one another over a network.  The more popular networks include the Internet Protocol (BACnet/IP) and the Master-Slave Token-Passing network (BACnet MS/TP).






Modbus Protocol is a messaging structure developed by Modicon in 1979. It is used to establish master-slave/client-server communication between intelligent devices. It is a de facto standard, truly open and the most widely used network protocol in the industrial manufacturing environment. It has been implemented by hundreds of vendors on thousands of different devices to transfer discrete/analog I/O and register data between control devices.

There are two implementations of Modbus that are found today in industry.  The first implementation is the traditional implementation of Modbus over a serial line called Modbus Serial.  The second implementation is more modern with Modbus operating over a TCP/IP network called Modbus TCP.