{"id":1638,"date":"2021-06-08T19:08:19","date_gmt":"2021-06-08T19:08:19","guid":{"rendered":"https:\/\/www.thepyroscope.com\/blog\/?p=1638"},"modified":"2024-05-29T02:06:35","modified_gmt":"2024-05-29T02:06:35","slug":"i-know-what-modbus-is-but-what-is-bacnet","status":"publish","type":"post","link":"https:\/\/www.thepyroscope.com\/blog\/i-know-what-modbus-is-but-what-is-bacnet\/","title":{"rendered":"\u201cI know what Modbus is, but what is BACnet?\u201d"},"content":{"rendered":"\n

-Rob Frohock<\/em><\/p>\n\n\n\n

See also: Modbus RTU verses Modbus TCP\/IP: What\u2019s the Difference?<\/a><\/p>\n\n\n\n

In industrial settings, Modbus is one of the oldest\nprotocols for devices to communicate their data digitally to a central\ncontroller.  It allows transmitters to\nsend integer data to controllers\u2026it allows controllers to send integer data to\nSCADAs\u2026and it is very easy to use.  BACnet\nis another protocol but started in the building automation sector and while it\nto can send integer data, BACnet was design to send many other types of data.  <\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

BACnet stands for \u201cBuilding Automation Control Network\u201d.  As the name implies, BACnet began as a\ncommunication standard for devices communicating to a building automation\nsystem.  These devices originally performed\nsimple tasks such as measuring flows through pipes and air ducts, even thermostats\nin commercial buildings.  Today much more\ncomplex devices, such as variable frequency drives and boiler control panels, use\nthis protocol to transmit hundreds of data points to the central control\nsystem.  <\/p>\n\n\n\n

BACnet started by using a RS-485 serial communication\nbackbone (called BACnet MS\/TP) similar to many other protocols.  It allows 31 devices to be daisy-chained on a\nsingle twisted wire pair that can be almost a mile long.  Over the years the speed (or \u201cbaud rate\u201d)\nincreased to allow more data to flow back to the central control system.  More recently, a variant protocol was created\nto use ethernet (called BACnet\/IP).  Ethernet\nis much faster than serial communications and allows hundreds of devices on the\nsame network.  It uses the same backbone as\nethernet found in office buildings.  It operates\nat 10 Mps, 100 Mps, or 1 Gps and can use the same devices that any ethernet network\nuses, such as managed switches, fiber optic cable, etc.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

BACnet is different from Modbus is several ways.  First, the data that BACnet sends can be much\nmore complex.  The data is organized in\n\u201cobjects\u201d and each object has \u201cproperties\u201d. \nFor example, a pressure transmitter might send one object called \u201cProcess\nPressure\u201d.  This object would have a\nproperty called \u201cObject Type\u201d set as \u201cAnalog Input\u201d; a property called \u201cCurrent\nValue\u201d; a property called \u201cHigh Alarm Setpoint\u201d; a property called \u201cCurrent\nStatus\u201d, etc.  Each one of these properties\nhas a value which could be an integer, a Boolean (True or False), a string of\ntext, or other forms of data.  The central\ncontrol system can be programmed to read all the properties, or just a few.  Each device can transmit many objects and each\nobject can have many properties, so the data available can be vast and complex.  Even video can be an object on BACnet\/IP.<\/p>\n\n\n\n

What also makes BACnet different from Modbus is a feature called \u201cdynamic device binding.”  Think of this as the central control system shouting to the whole network \u201cWho is out there?\u201d and all the devices responding with their name, address, and objects available.  This makes installing and commissioning a BACnet network much easier and less prone to errors in syntax when mapping the data from objects.  To provide all this functionality, manufacturers must program their devices exactly to the BACnet standard which is maintained by ASHRAE, but the BACnet Testing Laboratory provides a third-party service to ensure the product will perform correctly.<\/p>\n\n\n\n

If you are providing equipment that will communicate to the\ncentral control system at site, you will be informed of the protocol that is\nrequired.  If you are choosing a central\ncontrol system, the choice of protocol is an important one, as it controls the\ntype of data that will travel on the network. \nHowever, if you have devices that only communicate via Modbus, but need\nto be installed on a BACnet, there are protocol converters available to allow\nthis.  Note these protocols need to be programmed\nto convert the data from one protocol to another.<\/p>\n\n\n\n

 In summary, Modbus\nand BACnet will continue to be more popular in the sectors from with they\nstarted, but as industry and building automating continue to overlap, it is important\nto have a basic understanding of both of these protocols and know their\nadvantages.<\/p>\n","protected":false},"excerpt":{"rendered":"

-Rob Frohock See also: Modbus RTU verses Modbus TCP\/IP: What\u2019s the Difference? In industrial settings, Modbus is one of the oldest protocols for devices to communicate their data digitally to a central controller.  It allows transmitters to send integer data to controllers\u2026it allows controllers to send integer data to SCADAs\u2026and it is very easy to use.  BACnet is […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"content-type":"","footnotes":""},"categories":[10,7],"tags":[],"_links":{"self":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts\/1638"}],"collection":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/comments?post=1638"}],"version-history":[{"count":10,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts\/1638\/revisions"}],"predecessor-version":[{"id":1828,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts\/1638\/revisions\/1828"}],"wp:attachment":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/media?parent=1638"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/categories?post=1638"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/tags?post=1638"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}