The BACnet Telephone Override Module (BTOM) provides building occupants the ability to override lighting, HVAC or both from any touch-tone telephone. The BTOM provides human voice prompting that informs the caller what information is required to be entered via the telephone keypad. The factory default voice prompts are recorded in English and can be recoded in any language through the local program jack.

Native Protocols

The BTOM is capable of communicating with almost any BAS using one of the following native protocols:

Additional protocols are supported through the use of a Lumisys ELINK

• BACnet IP
• BACnet over PTP
• BACnet over ARCNET (156K)

• Modbus RTU
• Modbus ASCI

Simply the Best User Interface

Today, the telephone continues to hold claim to the most convenient user interface. Just think about some of the machines in our world that have copied the telephone; ATMs, Security Keypads, and TV remotes. So the question is how do we leverage the most convenient user interface in the greening up of our buildings?

The first opportunity is the use of the telephone to override lighting, HVAC or both. Imagine this….

You are in a building and the lights blink around 6pm to notify you that the lights are scheduled to turn off in 10 minutes. You need to work another hour to finish a report, so you hit the speed dial number from your desk phone for the override system. At the other end of the line, you hear a voice welcome you and it prompts you to enter your ID and pin#. Then the voice prompts you to enter 1 for Lighting, 2 for HVAC, or 3 for both. Then the voice prompt confirms your request and you hang up. The next morning you receive an e-mail that confirms the after hour usage and you forward the detail to accounting with your approval.

User Convenience

The telephone override scenario described provides the user with a readily accessible solution that is compatible with any phone and that requires no training or manual. The other factor, shown in figure 1, which impacts user convenience, is life cycle reliability. Web browser solutions are subject to compatibility issues with new operating systems or software releases which make these systems inherently less reliable than systems that are not subject to these constraints. It is also important to note that a web browser interface as compared to a touch tone interface is graphical in nature and is likely to require more work to maintain as the building ages.

Another common product used in buildings is occupancy sensors, which promote automatic off of lighting after a space is unoccupied for some period of time. Unfortunately occupancy sensors do not always deliver the performance that is promised. Other than occupant feedback, occupancy sensors are usually installed without any ongoing verification of actual performance. The lack of actual performance feedback makes this solution less reliable than solutions that provide verification. Anyone who has been in an office or restroom with an occupancy sensor that does not work as expected knows how well occupant feedback works; busted lens cap, countless phone calls, and finally a complete bypass or removal. This is not to say that all occupancy sensors are bad since, when they are properly applied, installed and maintained occupancy sensors are a useful component in an integrated energy management strategy.

	Low Voltage Override	Occupancy Sensor w/ Override Switch	Web Browser	Telephone Override
User Convenience
Readily Accessible	Low	Low	Medium	High
Acceptance of User Interface	High	Medium	Medium	High
Life Cycle Reliability	High	Low	Medium	High
Flexible
Retrofit Suitability	Low	Low	Medium	High
Simplicity (Technical)	High	Medium	Low	High
Allocate Consumption by User	No	No	Yes	Yes

Flexible

The telephone override scenario described also offers the owner a solution that lowers cost and increases profit. This is especially true for existing building owners that need a cost effective way to control energy without substantial construction expenditures or operation upheaval. The basic design of a telephone override solution is that it only requires power, a network connection to a building automation system and a dedicated telephone line, refer to figure 2. Unlike occupancy sensors and low voltage switches, there are no new wires for each zone because a telephone override leverages the existing infrastructure via the telephone.

Many building automation systems have the capability to provide tenant billing or cost allocation information, but they lack a verified override method that is simple and cost effective. Inherent in the design of the telephone override system is user verification, which is accomplished using the callers ID and pin#. Occupancy sensors and override switches are not designed for this purpose, and web browser solutions typically require a higher investment than a telephone override solution.

So as you consider the design of your building control system, telephone override should be at the top of the list of possible user interfaces. It is the most convenient and flexible user interface on the planet.

Documentation

BTOM Data Sheet
ELINK (web page)

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