HRW HPD0440BNMR V401 Manual 111116.doc E. & O. E. / Subject to change without notice
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BACnet Object Instances
Up to 110 function blocks exist in the device depending on the version. Because many objects may be
Binary or Analogue, and may be seen as an Input, an Output or a Value, the final total of discoverable
and device relevant object instances may be up to 124.
A physical universal input (UI) may be an AI (Analogue Input) or AV (Analogue Value) but
when used as a digital input then it’s object instance would be a BV (Binary Value)
A Virtual Universal Input (VUI) is seen as an AV (Analogue Value)
A physical digital output is a BO (Binary Output) by default but if programmed for PWM control,
which has a control value of 0…100%, then it is seen as an AV (Analogue Value)
Using UI3 as an example:
Description:
Physical
universal
input
Object
#: 19
Object Instance when binary DI:
BV19
Object Instance when analogue sensor:
AI19 or AV19
Using AL1 as an example:
Description:
Analogue
Logic
block
Object
#: 53
Object Instance when Digital function:
BV53
Object Instance when Analogue function:
AV53
The common reference in all cases is the object # therefore during device Object Discovery over the
network the option of Input, Output or Value is decided based on the programmed application use of the
object in question.
BACnet Priority Array
The BACnet protocol utilises a Priority Array for each object to enable various network devices to take
control of a device’s object based on the level of need. Priority 16 is the least significant level and may
be considered normal ‘Auto’ operating level. Priority 1 is the highest control level, generally used for
emergency control under fire condition or similar events.
In respect of this device:
The objects are null priority by default
Commands from the internal control program of the device are at priority level 16
Manual commands via terminal mode operate at priority level 9
Release of a manual results in an object reverting to next lowest and still valid priority level
Commands from the network to DO, AO, VUI and VDI objects are remembered after a power
reset if priority 1…8
Commands from the network to Proportion Band & Integral Time points of Control Loops are
written to those objects if other than null priority