Issue
What is required to control command priorities in 3rd party controllers using Plain English?
Product Line
Andover Continuum
Environment
- Continuum Cyberstation
- BACnet Controller (BCX, B4920, B3)
- BACnet command priority
- Plain English
Cause
Need to understand how to control command priorities and point values with Continuum workstation programs or controller infinity programs.
Resolution
Command Priority is a BACnet mechanism to decide the control hierarchy of a point, with 1 being the highest priority and 16 being the lowest. Consider the following:
- Default setting for a workstation program priority level is ManualOperator priority 8
- Programs located in the workstation default command priorities can be controlled through Bacnet Preferences
- Controller InfinityPrograms will need to use the WriteProperty function to set a different priority other than priority 10
- To relinquish a priority level use Relinquish(pointname, priority level)
The WriteProperty function is written in the format:
WriteProperty (object_name, value, priority, index)
object_name
- Includes a full pathname, followed by a property name.
- The object identifier and property identifier are combined as one argument
value
- This actual value to which the property is set.
- This is optional. If it is not present, then the next argument, priority, must be present to perform a Relinquish command. (See the example in Relinquish.)
priority
- The priority number, ranging from 1 (highest) to 16 (lowest).This is optional. It applies only to a set commandable property.
- For controllers: If it is not present, priority 10, if applicable, is used.
- For CyberStation: The value, based on the priority in the BACnet Preferences dialog, is used.
index
- This is optional. It applies only to an array-type BACnet property. The index is ignored whenever it is not applicable.
Infinity controller samples:
This line will write the value of 22 to priority 10
BACnetDevices\BNet_4444\B3_885\B3Num1 = 22
This line will write the value of 33 to priority level 4
WriteProperty(BACnetDevices\BNet_4444\B3_885\B3Num1, 33 , 4 )
This line will relinquish the value for priority level 4 setting the value back to NULL
Relinquish(BACnetDevices\BNet_4444\B3_885\B3Num1 , 4 )
