If you’re in industrial automation and spend most of your time around machines, you certainly know that industrial automation is radically different than it was twenty years ago when DeviceNet and then EtherNet/IP was introduced. Today, we have Cobots (collaborative robots) that work alongside our assemblers to do the tedious and difficult tasks. Today, we have cloud communications providers like Microsoft Azure and Amazon AWS to manage and process vast amounts of data. Today, we have increasingly more sensors – sensors on everything reporting back data like never before. It’s been one revolution after another in industrial automation.
It’s much the same in building automation – the organization and communication among all the devices required to operate a modern building. If you’ve never stopped to think about it, a building is a continuous production process. There’s electricity, water, heat, air conditioning, and light to continuously supply 24 hours a day without interruption. It’s a complicated process with one big, uncontrollable variable: the outside environment. Sometimes that outside environment is pleasant and unobtrusive but other times, it’s harsh and problematic. No matter the environment, the building automation system has to keep the inside environment warm and friendly.
A building is much like a production process with many of the same problems. They too have lots of legacy systems and lots of unique subsystems that are difficult to integrate into a cohesive whole. In the past, building automation used a lot of Modbus RTU and then Modbus TCP. Other building integrators standardized on some of the old versions of BACnet based on RS485 communications. And, of course, there were the vendors that supplied their own, proprietary systems to control the lights, heating, fire alarm systems, entry, and access systems. And just like industrial automation, these systems live on in a building that is twenty, thirty, or more years old where there is no ROI case to change them out.
As in many other systems, Ethernet is now the dominant media and transport layer for communications in modern buildings. BACnet/IP is now the most widely used protocol to connect the various building automation systems to a central controller. Siemens, Honeywell, and Johnson Controls dominate the market for building automation systems, and all use BACnet/IP for the majority of communications.
What is BACnet/IP? BACnet (Building Automation and Control Network) is a completely non-proprietary open protocol specification that defines both how data is represented on the network and the services that are used to move data from one BACnet node to another. It includes messages that identify data and network nodes such as Who-Is, I-Am, Who-Has, and I-Have.
In the early days of BACnet, prior to the advent of Ethernet, there were many different physical and data link technologies used to link devices over BACnet. Though some of those other transport mechanisms are still around, now BACnet commonly only uses RS485 and Ethernet transport mechanisms. BACnet MS/TP is the RS485 version of BACnet while BACnet IP is the most common Ethernet version of BACnet.
There are lots of places where building automation systems must communicate with industrial automation systems. RTA has built devices exactly for that. The 460ETCBC, for example, is a device that allows an AB PLC to provide data to a BACnet/IP building automation system. You can find other BACnet/IP interfaces on our BACnet products page.
In the next article on building automation, I’ll get into how BACnet represents data and how it uses Ethernet for communications.