When connecting a HVAC drive from one manufacturer to a device from a different manufacturer, users normally rely on gateways to translate the protocol and pass messages between the two. However, this method rarely works as well as an installation that uses a single protocol. Frequently, the only part of the sub-network visible to the rest of the network is the gateway, with lower level devices invisible once the protocol has been converted.
The solution is to use an open protocol in combination with a router, enabling full access to devices at all times. An open protocol is one that can be used by any manufacturer, while a router is a media converter. The router simply passes on messages as received, but over a different physical medium, without interpreting data from one protocol into another.
ABB has introduced an IP router - the RBIP-01 - for its BACnet-enabled HVAC drives. BACnet is an open protocol for building automation and control networks, giving users the freedom to select the most suitable equipment from a range of manufacturers. All BACnet devices communicate in the same language, without the expense of additional hardware. Equipment using BACnet is integrated without effort and gives more comprehensive information than other communication technologies when in use.
Routers play a key role in modern multi-vendor BACnet systems that use sub-networks for device integration. Like many controllers, the ABB HVAC drive uses master-slave/token-passing (MS/TP) over twisted pair EIA-485 wiring, which ensures reliable communication over longer cable lengths.
Internet Protocol (IP) has become widely accepted in recent years and many companies use an Ethernet backbone for their intranet and building management system (BMS). While it can be difficult to make systems with proprietary communication protocols talk to each other, switching from MS/TP to IP is a simple operation. The new RBIP-01 module provides an easy way to connect the two network types together, making the ABB standard drive for HVAC compatible with a range of BACnet/IP devices and workstations from different manufacturers.
All that is needed to configure the new IP router is to set the IP address. No tools or cable are needed, apart from an Ethernet cable (provided with the router) for connection to a PC. Nor is any software required, as the configuration window opens in an ordinary web browser. The RBIP-01 module can also be named to make network browsing as easy as possible.
The module is fully compatible with the ABB standard drive for HVAC, including older product generations, and is fitted inside the drive. It is powered by a 24V ac or dc supply from the drive or an external source. It supports all standard MS/TP baud rates up to 76,800 baud. The module is easy to use and simple to install with built-in ‘help’ functionality. Its default configuration meets the requirements of the ABB HVAC drive, enabling plug-and-play connectivity.
As well as being a BACnet router, the RBIP-01 also provides 200MB storage capacity for manuals and other documentation; this memory can also be accessed by the user for storage of additional information, such as project-specific data. All the documentation for ABB HVAC drive, as well as RBIP-01 documentation in several languages, is embedded in the router memory as standard. Drives can either be equipped with one RBIP-01 router module each, or daisy-chained into a sub-network. In the latter case, one router can manage up to 31 drives wired to an MS/TP segment of up to 1.2km in length.
BACnet MS/TP over EIA-485 provides a cost-effective way to connect several devices to the BACnet network, compared with the more substantial cabling and switching equipment required for Ethernet networks. Considering that each direct digital controller (DDC) often has over 20 drives, substantial savings can be made when using MS/TP instead of Ethernet, while still achieving the required transmission speed.
Drives with built-in, native BACnet save time, reduce installation costs and make monitoring and fault finding easier. Moreover, the drive’s I/O points are free for use by other devices over the BACnet network, enabling the drive to be used as a remote outstation.
The drive supports 73 objects (device object, binary inputs, binary outputs, analogue inputs, analogue outputs, binary values and analogue values). This offers an effective compromise between advanced functionality and low complexity, providing network access to most typical internal binary and analogue objects.
BACnet can be used to integrate the BMS with the heating and ventilation system, fire alarm, intruder protection and other systems in the building, from field up to management level. Supervisory personnel working from home, for example, can dial in and get the same functionality as at the workstations in their offices.
The ABB HVAC drive is BTL approved (2004) and in 2008 became B-ASC (BACnet Application Specific Controller) compliant. It was the first BACnet certified drive product in 2008, ensuring conformance to BACnet standard ISO 16484-5:2007. Since its introduction in 2004, more than 20,000 have been installed annually - all BACnet enabled – and ABB believes it is the only drive on the market with a BACnet/IP router, allowing direct connection from Ethernet without external routing controllers.