BACnet Driver

BACnet Driver Configuration

Communicating with BACnet devices requires that the BACnet Proxy Agent is configured and running. All device communication happens through this agent. The BACnet Proxy Agent can be installed from PyPi using vctl:

vctl install volttron-bacnet-driver

Driver Config

There are nine arguments for the driver_config section of the device configuration file:

device_address - Address of the device. If the target device is behind an IP to MS/TP router then Remote Station addressing will probably be needed for the driver to find the device

device_id - BACnet ID of the device. Used to establish a route to the device at startup

min_priority - (Optional) Minimum priority value allowed for this device whether specifying the priority manually or via the registry config. Violating this parameter either in the configuration or when writing to the point will result in an error. Defaults to 8

max_per_request - (Optional) Configure driver to manually segment read requests. The driver will only grab up to the number of objects specified in this setting at most per request. This setting is primarily for scraping many points off of low resource devices that do not support segmentation. Defaults to 10000

proxy_address - (Optional) VIP address of the BACnet proxy. Defaults to platform.bacnet_proxy. See Communicating With Multiple BACnet Networks for details. Unless your BACnet network has special needs you should not change this value

ping_retry_interval - (Optional) The driver will ping the device to establish a route at startup. If the BACnet proxy is not available the driver will retry the ping at this interval until it succeeds. Defaults to 5

use_read_multiple - (Optional) During a scrape the driver will tell the proxy to use a ReadPropertyMultipleRequest to get data from the device. Otherwise the proxy will use multiple ReadPropertyRequest calls. If the BACnet proxy is reporting a device is rejecting requests try changing this to false for that device. Be aware that setting this to false will cause scrapes for that device to take much longer. Only change if needed. Defaults to true

cov_lifetime - (Optional) When a device establishes a change of value subscription for a point, this argument will be used to determine the lifetime and renewal period for the subscription, in seconds. (Defaults to 180)

Here is an example device configuration file:

{
    "driver_config": {"device_address": "10.1.1.3",
                      "device_id": 500,
                      "min_priority": 10,
                      "max_per_request": 24
                      },
    "driver_type": "bacnet",
    "registry_config":"config://registry_configs/vav.csv",
    "interval": 5,
    "timezone": "UTC",
    "heart_beat_point": "heartbeat"
}

A sample BACnet configuration file can be found here or in the volttron-lib-bacnet-driver repository.

BACnet Registry Configuration File

The registry configuration file is a CSV file. Each row configures a point on the device.

Currently, the driver provides no method to access array type properties even if the members of the array are of a supported type.

The following columns are required for each row:

Volttron Point Name - The name by which the platform and agents running on the platform will refer to this point.

Units - Used for meta data when creating point information on the historian.

BACnet Object Type - A string representing what kind of BACnet standard object the point belongs to. Examples include:

analogInput

analogOutput

analogValue

binaryInput

binaryOutput

binaryValue

multiStateValue

Property - A string representing the name of the property belonging to the object. Usually, this will be presentValue

Writable - Either TRUE or FALSE. Determines if the point can be written to. Only points labeled TRUE can be written to through the Actuator Agent. Points labeled TRUE incorrectly will cause an error to be returned when an agent attempts to write to the point

Index - Object ID of the BACnet object

The following columns are optional:

Write Priority - BACnet priority for writing to this point. Valid values are 1-16. Missing this column or leaving the column blank will use the default priority of 16

COV Flag - Either True or False. Determines if a BACnet Change-of-Value subscription should be established for this point. Missing this column or leaving the column blank will result in no change of value subscriptions being established.

Any additional columns will be ignored. It is common practice to include a Point Name or Reference Point Name column to include the device documentation’s name for the point and Notes and Unit Details columns for additional information about a point.

BACnet
Point Name	Volttron Point Name	Units	Unit Details	BACnet Object Type	Property	Writable	Index	Notes
Building/FCB.Local Application.PH-T	PreheatTemperature	degreesFahrenheit	-50.00 to 250.00	analogInput	presentValue	FALSE	3000119	Resolution: 0.1
Building/FCB.Local Application.RA-T	ReturnAirTemperature	degreesFahrenheit	-50.00 to 250.00	analogInput	presentValue	FALSE	3000120	Resolution: 0.1
Building/FCB.Local Application.RA-H	ReturnAirHumidity	percentRelativeHumidity	0.00 to 100.00	analogInput	presentValue	FALSE	3000124	Resolution: 0.1
Building/FCB.Local Application.CLG-O	CoolingValveOutputCommand	percent	0.00 to 100.00 (default 0.0)	analogOutput	presentValue	TRUE	3000107	Resolution: 0.1
Building/FCB.Local Application.MAD-O	MixedAirDamperOutputCommand	percent	0.00 to 100.00 (default 0.0)	analogOutput	presentValue	TRUE	3000110	Resolution: 0.1
Building/FCB.Local Application.PH-O	PreheatValveOutputCommand	percent	0.00 to 100.00 (default 0.0)	analogOutput	presentValue	TRUE	3000111	Resolution: 0.1
Building/FCB.Local Application.RH-O	ReheatValveOutputCommand	percent	0.00 to 100.00 (default 0.0)	analogOutput	presentValue	TRUE	3000112	Resolution: 0.1
Building/FCB.Local Application.SF-O	SupplyFanSpeedOutputCommand	percent	0.00 to 100.00 (default 0.0)	analogOutput	presentValue	TRUE	3000113	Resolution: 0.1

A sample BACnet registry file can be found here or in the volttron-lib-bacnet-driver repository.