Point with writable output using 16-level priority array. Writable points typically are a setpont 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:
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).
def | writable-point |
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doc | See above |
is | point |
lib | phIoT |
pointFunction | pointFunctionType |
pointQuantity | quantity |
pointSubject | phenomenon |
marker |
Marker labels a dict with typing information |
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entity |
Top-level dicts with a unique identifier |
point |
Data point such as a sensor or actuator |
cur |
Supports current value |
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dis |
Display name for an entity |
enum |
Defines an eumeration of string keys |
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 before Haystack 4.0 to identity data types |
maxVal |
Inclusive minimum for a numeric value |
minVal |
Inclusive maximum for a numeric value |
siteRef |
Reference to site which contains the entity |
spaceRef |
Reference to space which contains this entity |
tz |
Timezone identifier from standard timezone 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 |