More info on the BACnet Protocol

The Monico Gateway supports BACnet MSTP (RS-485/RS-232) and BACnet UDP (Ethernet) by placing scaled, analog, 32-bit Integer and 32-bit Floating Point, values into Analog Input (AI) registers and digital data into Binary Inputs (BI) registers. Please see our CDL and J1939 Combined Data Maps in the Support section of this website for a complete list of the Register Mappings. In addition, we offer default configurations which require simple changes to the MAC Address and or Password for MSTP or the IP address for UDP versions.


BACnet (Building Automation and Control Network) is one of the 3 most widely used protocols with worldwide usage and is a national standard in more than 30 countries. It is not a software application, or a piece of hardware, or firmware in an embedded device. It is a protocol that outlines how computers and devices and/or sensors exchange data. The beauty of BACnet is it's interoperability or ability to integrate many devices from a large number of manufacturers into a single network or system. It debuted in February 1996 at the International Air-Conditioning, Heating, and Refrigerating Exposition.


Development started in 1987 and with the subsequent adoption of ANSI/ASHRAE 135-1995 BACnet became an American National Standard in 1995. In 2003 ISO approved ISO 16484-5 for publication making it an international standard. The European committee for Standardization, CEN, has also adopted it most recently in May of 2014. The goal was to provide a standard communications protocol so that building system control devices like HVAC/R, power, elevator, security and access, lighting, life safety, and other systems could communicate on the same network. The Monico Gateway extends that reach to engines and power generation products.


BACnet is an open and nonproprietary protocol communications standard. Because it is an open protocol, it allows companies to adopt it knowing that they are not limited to specific vendors using equipment that can easily become outdated or obsolete. This flexibility also means that customers can choose from a wide range of manufacturers and not be forced into a single supplier solution. It also works in today's most commonly found networks around the world. Some examples are; Ethernet, RS-485(MSTP), RS-232(MSTP), and Ethernet(UDP) and the LonTalk™ data link layers. Ensuring that the protocol will continue to be robust and practical in the future full public scrutiny is required when changes are suggested. Only after the changes have been vetted publicly will they be adopted in future revisions. To make sure that devices conform to the BACnet standard a testing laboratory was created. Out of this came a complete set of testing procedures that manufacturers can use when developing new products or testing existing ones.


The protocol specification defines how messages are delivered between devices and the messages themselves. There is an object for the 3 data types, BIT, 32-bit Integer, and 32-bit REAL. Each Object contains properties that are defined as standard or as vendor specific each of which function and behave according the BACnet standard protocol. The BACnet standard defines 18 standard objects which includes analog inputs and outputs, binary inputs and outputs, and schedules.


The BACnet protocol defines messages that various devices exchange and how those messages are delivered. Each piece of information (BIT, 32-Bit Integer, or 32-Bit Real) is represented by an Object. Each Object contains standard, or defined, properties but may contain vendor defined properties as long as these function according to the standard. Included in the definition of each property is the expected behavior from for that object. There are 18 standard objects including analog inputs and outputs, binary inputs and outputs, and schedules. A service is defined in the BACnet standard as how devices exchanges messages or data. This includes reading values/data from or writing to a property in the device. The definition includes a broad range of services to access devices and their properties.


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