writable-point – Project Haystack

def

writable-point

Point with writable output using 16-level priority array. Writable points typically are a setpoint or actuator command. Haystack writable points are modeled on the BACnet 16-level priority array with a relinquish default which effectively acts as level 17.

The following levels have special behavior:

Level 1: highest priority reserved for emergency overrides
Level 8: manual override with ability to set timer to expire back to auto
Default: implicitly acts as level 17 for relinquish default

The priority array provides for contention resolution when many different control applications may be vying for control of a given point. Low level applications like scheduling typically control levels 14, 15, or 16. Then users can override at level 8. But a higher levels like 2 to 7 can be used to trump a user override (for example a demand response energy routine that requires higher priority).

The actual value to write is resolved by starting at level 1 and working down to relinquish default to find the first non-null value. It is possible for all levels to be null, in which case the overall write output is null (which in turn may be auto/null to another system). Anytime a null value is written to a priority level, we say that level has been set to auto or released (this allows the next highest level to take command of the output).

Also see Points chapter.

conjunct

writable	Supports writing data
point	Data point such as a sensor or actuator

def	writable-point
doc	See above
is	point
lib	lib:phIoT

usage

writable point

supertypes

marker	Marker labels a dict with typing information
entity	Top-level dicts with a unique identifier
point	Data point such as a sensor or actuator

tags

cur	Supports current value
dis	Display name for an entity
enum	Defines an eumeration of string key names
equipRef	Reference to equip which contains this entity
his	Supports historization of data
id	Defines the unique identifier of an entity in system using a `ref` value type
kind	Kind name used to identity a value data type
maxVal	Inclusive maximum for a numeric value
minVal	Inclusive minimum for a numeric value
pointFunction	Classifies the point as a sensor, command, or setpoint
pointQuantity	Quantity the point senses or controls
pointSubject	What the point senses or controls
siteRef	Reference to site which contains the entity
spaceRef	Reference to space which contains this entity
systemRef	Reference to system
tz	Timezone identifier from standard timezone database
unit	Unit identifier from standard unit database
writable	Supports writing data
writeErr	Error description when `writeStatus` indicates error condition
writeLevel	Current priority level for `writeVal` as number between 1 and 17
writeStatus	Current status of a writable point output
writeVal	Current desired value to write to output

Project Haystack

def

writable-point

conjunct

meta

usage

supertypes

tags