Glossary > P

 


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peer-to-peer

A type of network in which messages are passed between each node, and each node is an equal peer on the network.

 

A control strategy in which independent intelligent devices share information directly with each other and make their own control decisions without the need or delay of using an intermediate, central, or master controller.

 


Photocell

Light-sensitive device used to operate fixtures according to available daylight. They are used in solar lighting and to turn outdoor or security lights on and off at dusk and dawn.

 


PICs

Acronym for Protocol Implementation and Conformance Statement

 

A PICS is a tool for consulting engineers, vendors and customers to determine the BACnet implementation of a given device. The PICS is generally provided in a format that is common among vendors ( format is specified by ASHRAE ). A PICS is useful when comparing BACnet devices among various vendors to determine functionality and interoperability. The PICS may be used to determine what functionality devices are capable of supporting and what functionality is interoperable with other BACnet devices.

 


Pilot Light (LED or Lamp)

A "Pilot Light" indicates the on/off state of the circuit controlled by the switch.  Some Energy codes require the occupant to be able to see the on/off state of the lighting circuit even when the switch is not located in the area where the lights are. A Pilot Light on a wall switch meets this requirement.

On the other hand a Locator light on a wall switch helps the occupant find the switch in the dark.

 


Plenum

The space between the ceiling and the floor or roof above.


PMT

Acronym standing for Protocol Mapping Tool used to build mappings for open protocols.

 


POLL

An explicit request to a node for the value of one of its network variables.

 


POLLing

A method of monitoring Network Variables. Periodically, as specified by the polling rate, the browser will request and display the value of a network variable. This capability is useful when the network variable value changes rapidly. If the network variable value changes rarely, polling causes unnecessary network traffic and COV monitoring is recommended.

 


Power Feed

The connection point that brings electricity to track and other lighting systems. Power feed may be at the end, floating or at a wiring intersection.

 


Property, BACnet

The means by which objects are monitored and controlled. BACnet specifies many properties of objects; however three properties must be present in every object:

Object-identifier
Object-name
Object-type

 

BACnet also requires that certain objects support specific additional properties. The type of object and the type of device in which that object resides determine which properties are present. Some properties can accept writes, and others can only be read.

 


Protocol Implementation Conformance Statement - PICS

A written document, created by the manufacturer of a device, which identifies the particular options specified by BACnet that are implemented in the device.