Viconics VT8600 Series BACnet Integration Guide - Manual (Page 34)

VT8600 Series BACnet ® Integration Manual 34
Viconics Technologies Inc. | 9245 Langelier Blvd. | St.-Leonard | Quebec | Canada | H1P 3K9 | Tel: (514) 321-5660 | Fax: (514) 321-4150
028-0437-00 www.viconics.com | [email protected] March 2015
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Note F)
Physical hardware output objects.
Object examples in this category: BO95 / BO4 High Speed fan, AO123 / UO11 Analog Status. All physical
hardware output objects are writable.
CAUTION NEEDS TO BE EXERCISED since bypassing the internal
control functions of the controller CAN RESULT in damage to the equipment.
Writing and binding to the priority array 4 to 16 property is a method to use IF the requirement is to lock the
controller program and prevent physical hardware output objects from being powered based on the internal
operation of the controller application programming.
When writing and binding to the priority array 4 to 16, the control will NOT store and archive to flash memory
and will simply use it in RAM. As soon as the new present value is received in priority array 4 to 16, the con-
troller will use this new present value in all its internal control logics and functions.
When writing and binding to the priority array 4 to 16, the controller internal control logics and functions
ARE bypassed, and the controller will NOT operate with its own present values, but will be forced to use
the last write commands received on priority array 4 to 16 for its built-in internal control logics and functions.
HOWEVER, since these present values are only stored in RAM and not in flash, if a power reset occurs, the
override type function will be lost and the controller will start to operate using the relinquish default value. If the
override type function is required, a new write command to priority array 4 to 16 is needed.
The controller fully supports native and BACnet compliant priority array 1 to 16
write commands. This simply means that a write value at level 4 has a higher
authority than a write at level 9.
When writing and binding to priority array 4 to 16, you locally identify if an over-
ride is effective on a status object using the test output view or the service view.
The point will be highlighted in
RED indicating a write command to priority array
4 to 16. In this case, the present value used by the controller internal control
logics is bypassed and the value displayed and used is the last write command
received at priority array 4-16.
The ONLY way to release the override due to the use of writing to priority array
4 to 16 is to send a write NULL command to the proper priority array currently
locking the controller.
Physical hardware
outputs are processed
by BACnet Priority
Array 4 -16 value
BACnet Relinquish
Default network write
Internal controller program
under normal operation
BACnet Relinquish
Default value
BACnet Priority
Array 4 -16 value