What is a BACnet Gateway?
A BACnet gateway connects and translates devices that utilize differing network protocols, such as Modbus, to a BACnet network. This facilitates the intercommunication of devices that utilize a variety of network protocols and allows such devices to interoperate on a BACnet network.
BACnet gateways are responsible for more than simply retransmitting data across a network. The gateway receives encoded data from a variety of protocols, decodes the data, and then re-codes it as the desired protocol. Data flows both to and from the gateway as determined by the rules of the protocol. This is what allows for both BACnet and non-BACnet devices to operate within a single building automation system.
A typical scenario in industrial applications is the requirement to translate Modbus to BACnet as Modbus is a common communication protocol that can be found in industrial PLCs. However, to ensure interoperability of all devices on the network, the devices must speak a common language. BACnet devices on this network (BACnet IP or BACnet MS/TP) will not be able to communicate with the PLC without the use of a BACnet gateway to translate Modbus registers into BACnet objects. The BACnet gateway enables use of a standard, industrial PLC on a BACnet network in building automation applications.
The diagram below illustrates how the BACnet gateway acts as a translator between BACnet and non-BACnet network within a building automation system, transmitting messages in the appropriate protocol across networks.
What is a BACnet Router?
BACnet routers differ from BACnet gateways in that they are designed to transmit communications from BACnet devices to other BACnet devices within the network. BACnet routers are commonly used to connect BACnet IP to BACnet MS/TP devices. These network types differ in both their wiring (Ethernet vs. Serial) and also in the structure of each network packet. A BACnet router can bridge the gap between the two physically different networks so that devices of each type are connected. Where a BACnet gateway is used to translate a variety of protocols into BACnet, the BACnet router simply forwards data across the BACnet network.
BACnet Gateway on AcuLink 810
The AcuLink 810 is an intelligent data acquisition server and gateway that allows users to collect data from all Accuenergy meters, sensors, and third party devices. One of the most important features that AcuLink supports is that it can be used as a BACnet Gateway to collect data from both Modbus and BACnet devices at the same time. When the AcuLink 810 works as a BACnet gateway, it supports both BACnet MS/TP and BACnet IP devices. It also allows Modbus TCP and MBus devices to be converted into BACnet IP. In summary, The AcuLink 810 allows users to convert both Modbus RTU and BACnet MS/TP devices to BACnet IP devices, and then access these devices through an Ethernet or WiFi connection.
When BACnet MS/TP devices are connected to the AcuLink 810, they can use both the RS485 and USB ports at the same time. However, these two ports are set to read Modbus protocol by default. Users need to configure either the AcuLink’s USB or RS485 ports for BACnet protocol. Users can connect to both Modbus and BACnet devices simultaneously via USB and RS485 ports on the AcuLink 810.
The AcuLink 810 can also collect data from BACnet IP devices. After the device’s model name, serial number, port number, and device instance are correctly configured in the AcuLink 810 the BACnet IP device can be auto-detected and connected to the AcuLink 810.
Before adding BACnet devices to the AcuLink 810, the most important step is to import the proper BACnet template. BACnet templates are used in the AcuLink 810 to correctly read metering data from Accuenergy and third party BACnet devices. Before a device can be added to the gateway, a BACnet template for the device must be uploaded and installed onto the unit. The template can be manually imported from a .def file or converted from an EPICS file.