BACnet is a data communication protocol for Building Automation and Control Networks. Developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), BACnet is a national standard in more than 30 countries around the world, and an ISO global standard.
The BACnet protocol defines a number of different data link (physical) layers, with the two most common being BACnet/IP and BACnetMS/TP. BACnet/IP uses a IPv4 network as its backbone, while BACnetMS/TP uses RS-485 (half-duplex) to create a network of devices.
The information in this page is targeted at the TS-7680. The TS-7680 was designed from the ground up to support many features common to BACnet networks, including RS-485, two 10/100 ethernet interfaces, and the ability to operate at 24 VAC or VDC input.
All of the material and information below should work without issue on every other Technologic System's product, as all of the tools are userspace applications that rely on the kernel only for ethernet or RS-485 data transport. However be advised that there may be some hurdles along the way.
This demo uses two different BACnet devices, the iSMA-B-4I4O-H-IP for BACnet/IP, and the RIBTW2401B-BC for BACnetMS/TP.
The iSMA-B-4I4O-H-IP is a DIN rail mountable device, with 4 dry contact inputs and 4 output relays. It is powered from 24 V AC/DC, and includes 4 switches that can be used to manually override the output relays. The device supports MODBUS RTU, MODBUS ASCII, and of course BACnet/IP. While there is an RS-485 port, the -IP variant of the device is only set up to allow BACnet/IP or MODBUS TCP/IP; the RS-485 port is only set up to act as a MODBUS TCP/IP -> RS-485 gateway. Under the main cover is a set of DIP switches to select mode, baud, and set a factory reset.
The RIBTW2401B-BC is a much more simple device contained in a flat square enclosure. It has a single dry contact input, and a single output relay. It can be powered from 24 V AC/DC or 120 V AC. The output relay does have an override, however it is located on the internal DIP switch header and is not necessarily practical for ready use. The device support BACnetMS/TP vis RS-485. Inside of the unit is a set of DIP switches to set the baud rate, network address, and override current relay position.