Priority Array

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This is a BACnet Array of exactly 16 output values that get mapped into the Present Value according to the highest priority. If there are no values in the array, then the Relinquish Default is used.

Characteristics of Priority Arrays

  • See Section 19.2 of the specification for a description of how Priority Arrays work
  • Priority are BACnet Arrays
  • Priority Arrays are Read Only
  • As with all BACnet Arrays, reading index 0 of the priority array shall return the length of the array, in this case, the length shall be 16

Operation in a controller

The accepted method of operation of a Priority Array within a controller is to feed the output of the local control algorithm to the Relinquish Default property.

  • The Present Value is fed to the Physical Output of the device.
  • If the BACnet Object is not Out of Service, and there are no entries at all in the Priority Array itself, then the Relinquish Default is fed through to the Present Value property, and thus to the Physical Output of the BACnet Object, if one exists.
  • If the BACnet Object is Out of Service, then writes to the Present Value are allowed, and this value is transferred to the Physical Output of the device

On Restart

Option 1 - Priority Array assumes a pre-programmed default
Option 2 - Priority Array retains last written values
Standard Command Priorities
Value Description
1 Manual Life Safety
2 Automatic Life Safety
3
4
5 Critical Equipment Control
6 Minimum On/Off
7
8 Manual Operator
9
10
11
12
13
14
15
16



Keyword List
APDU BBMD BVLC BVLL DADR DNET Encoding I-Am LSAP MAC NPCI NPDU NSAP NSDU SA SADR SNET

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