KMC BAC-10000 manual Definitions of Terms, For this document are included on this

Definitions of Terms

For definitions of various terms in this document, refer to the award-winning pocket-sized Green Building and Con- trols Glossary (SB-046). A hyperlinked online version can be downloaded from the Brochures section of KMC Controls web site, www.kmccontrols.com. Some of the more important glossary terms

for this document are included on this page:

Air Handling Unit (AHU\—An HVAC system compo- nent that conditions and delivers air through the system. It typically contains one or more supply and return fans, heating/cooling coils, and filters to condition the air.

BACnet® (Building Automation Control Network\— An interoperable, nonproprietary, communica- tion protocol standard conceived by a consor- tium of building managers, system users, and manufacturers. BACnet defines how information is packaged for transportation between building automation system vendors.

EIA-485—A serial communications standard in which the voltage difference between two wires conveys the data. It is commonly used to network controllers via twisted-pair wiring. It was for- merly known as RS-485.

Fan Coil Unit (FCU\—A fan terminal unit that condi- tions the air in a single room or zone. FCUs gen- erally contain heating and cooling coils and have the ability to supply outside air to a space.

Heat Pump Unit (HPU\—A unit that uses direct expansion to remove or add heat to a space. On a call for heat, the heat pump pulls heat from a source such as outside air or the ground and puts it into a space. On a call for cooling, the process is reversed.

Max Master—The highest MAC address a device will attempt to locate when polling for master devices on the local network.

MS/TP (Master Slave/Token Passing\—A protocol (using the EIA-485 signaling standard) in which master devices can initiate requests for data but slave devices cannot (since slaves can only reply to messages from other devices). KMC advanced application controllers are all MS/TP master devices.

Native BACnet Device—A device that is fully BACnet compatible and uses BACnet as its primary, if not exclusive, method of communication.

PID (Proportional Integral Derivative) Control—A control algorithm that enhances the PI control algorithm by adding a component that is pro- portional to the rate of change (derivative) of the deviation of the controlled variable. This com- pensates for system dynamics and allows faster control response.

PID Loop Controller—A controller with an algorithm that calculates an output value that is based on the sensed value and the required setpoint. PID loop controllers provide more accurate and stable control than simpler controllers.

Proportional Control—A type of control in which a controlled device may operate at any position be- tween fully closed to fully open. Within a specific range, the output response maintains a constant ratio to the input signal.

Protocol—A definition or set of communication rules by which information is exchanged between de- vices on a network.

Real Time Clock (RTC\—A device that keeps track of the current time in a controller even if power is interrupted for a period of time.

Relative Humidity (RH\—The ratio of the amount of water vapor in air to the maximum amount of water vapor that could be in the air if the vapor were at its saturation conditions.

Roof Top Unit (RTU\—An HVAC unit that is supplied as a package and installed outside of a building.

Router—A device that connects two or more networks and chooses the best path for data packets.

USB (Universal Serial Bus\—A popular, plug-and- play, high-speed, serial computer interface.

UTC (Coordinated Universal Time\—An international standard for determining time zones.

Variable Air Volume (VAV\—A method of tempera- ture control in which the volume of constant tem- perature supply air exiting a duct is modulated (via dampers) to maintain a temperature setpoint in an individual space.

BAC-10000 Series 25 Operation Guide, Rev. J